Abstract
Objectives
The present study was conducted to estimate the effectiveness of (BBIBP)-CorV (Sinopharm), ChAdOx1-S/nCoV-19 (AZD1222, Oxford-AstraZeneca), rAd26-rAd5 (Gam-COVID-Vac, Sputnik V), and BIV1-CovIran (COVIran Barekat) and BBV152 COVAXIN (Bharat Biotech) vaccines against hospitalization and death of COVID-19 in Guilan Province of Iran from May 22 to December 21, 2021.
Methods
This test-negative case-control study was conducted on the population aged 5 years and above by extracting information from local databases (The Medical Care Monitoring Center and The Integrated Health System). A logistic regression analysis was performed to estimate the effectiveness of the vaccines against COVID-19 hospitalization and death.
Results
The total study population was 42,084, including 19,500 cases (with a positive Reverse Transcriptase-Polymerase Chain Reaction test admitted to hospitals in Guilan Province) and 22,586 controls (with a negative Reverse Transcriptase-Polymerase Chain Reaction test). Among the admitted patients, 1887 deaths occurred. The maximum effectiveness of BBIBP-CorV (Sinopharm) in preventing temporary hospitalization and regular hospitalization was observed 151 days after receiving the second dose, 95% (95% CI: 67-99.4%) and 85% (95% CI: 77-91%) respectively. The maximum effectiveness of the BBIBP-CorV (Sinopharm) vaccine 91-120 days after receiving the second dose against death was showed 56% (95% CI: 33-71%). The maximum effectiveness of ChAdOx1-S/nCoV-19 (AZD1222, Oxford-AstraZeneca) and BIV1-CovIran (COVIran Barekat) in preventing regular hospitalization and death was observed 121-150 and 61-90 days (respectively) after receiving the second dose, reaching 98% (95% CI: 94-99%) and 92% (95% CI: 48-99%), respectively for ChAdOx1-S/nCoV-19 and 95% (95% CI: 91-97%) and 89% (95% CI: 55-98%) respectively, for BIV1-CovIran.
Conclusion
For almost all vaccines, the study observed an increase in effectiveness against hospitalization and death over time.
Keywords: COVID-19, Vaccine, Effectiveness, Pandemic
Introduction
Iran has experienced a high rate of death during the pandemic of COVID-19 [1,2]. The first case of the disease in Iran was reported on February 17, 2020 [2], And Iran reported its first COVID-19 deaths on February 19, 2020 [3]. From the outset of the pandemic, various strategies were proposed to overcome this emergency crisis, including quarantine and social distancing, each of which had its limitations and problems [2]. News of the production of vaccine for the disease sparked hope once again, and many countries have started mass vaccination to combat the disease [4]. COVID-19 vaccines are novel products with Emergency Use Authorization (EUA). Like other drugs, these products should be evaluated in terms of their effectiveness and side effects in the post-market stage based on World Health Organization (WHO) guidelines [4,5].
The vaccination program of the Islamic Republic of Iran began with patients who had immunodeficiency disorder, older adults, and healthcare workers using the Sputnik V vaccine on February 9, 2021, and was subsequently expanded through other COVID-19 vaccines (Sinopharm and AstraZeneca), which were authorized by the Iranian Ministry of Health and Medical Education (MoHME) [6], [7], [8].
Since the Alpha, Beta, Gamma, and Delta variants of SARS-CoV-2 are concerning variants of the virus that are associated with increased disease transmission and more severe conditions (increased hospitalization and death), they can play a concerning role in reducing the antibodies produced upon the previous infection or in decreasing the effectiveness of vaccination [9], [10], [11], [12], [13], [14]. Therefore, it is pivotal to assess the effectiveness of vaccination against concerning variants of COVID-19. To the best of our current knowledge, some studies have been carried out on the effectiveness of vaccination against COVID-19 variants [15], [16], [17]. There are several concerns about the effectiveness of the available vaccines in areas with a wide distribution of COVID-19 variants. For example, the results of a meta-analysis revealed that full vaccination (Sinopharm, AstraZeneca, etc.) has high effectiveness against alpha and moderate effectiveness against Delta and gamma variants, while incomplete vaccination (one dose) showed little effectiveness against all the variants of COVID-19 [18]. The effectiveness of vaccines against COVID-19 was estimated using a test-negative case-control study, which is the standard design for evaluating the effectiveness of vaccines against influenza and COVID-19 [16,19,20].
In Guilan Province of Iran, vaccination against COVID-19 started on February 12, 2021, for high-priority groups. Vaccine coverage for the entire population with all three doses has been continuously growing since February 2021 until present time. Until December 21, 2021, the first, second, and third doses have been administered to 94%, 85%, and 10% of the population, respectively. Since Guilan is a tourist destination, a percentage of the vaccines have been injected to non-natives. The net vaccination coverage in the target population of Guilan (n = 2,235,600) has thus been 84% for the first and 75% for the second doses.
This study seeks to estimate the effectiveness of the vaccines used in Guilan against disease consequences, namely hospital admission of patients with a positive polymerase chain reaction (PCR) test with different classifications of disease severity (including: temporary, regular, and intensive care unit [ICU] admissions) and the associated death, and to compare the vaccination status of these individuals with those who have had a negative PCR test (outpatients in center of sampling covid-19) at different intervals after receiving the first, second, and third doses (from May 22 to December 21, 2021), when the circulating variants were alpha and Delta in Guilan Province.
Methods
Objectives and design
The effectiveness of vaccines against COVID-19 was estimated using a test-negative case-control study, The key to this design is to control the bias created by the misclassification of infection and the differences in healthcare-seeking behaviors between vaccinated and unvaccinated individuals [21,22]. This test-negative case-control study seeks to estimate the effectiveness of the vaccines used in the study setting, including BBIBP-CorV (Sinopharm), ChAdOx1-S/nCoV-19 (AZD1222, Oxford-AstraZeneca), rAd26-rAd5 (Gam-COVID-Vac, Sputnik V), and BIV1-CovIran (COVIran Barekat) and BBV152 COVAXIN (Bharat Biotech) vaccines on different severities of illness in hospitalized patients with a positive PCR test (case group), with the severity classification encompassing temporary, regular, and ICU admission, and disease-related death, and to compare the vaccination status of these people with those who have had a negative PCR test (outpatients in center of sampling covid-19) at different intervals after receiving the first, second, and third doses from May 22 to December 21, 2021.
Data sources
All the data were extracted from the following two sources:
MCMC: The Medical Care Monitoring Center is a system for recording the demographic and clinical information of patients after hospital admission. In this system, a patient who shows symptoms such as dyspnea, persistent chest pain, and oxygen saturation <95% is taken as a case of acute respiratory disease. All COVID-19 admissions and outcomes, including discharge and death, are recorded in this system. The results of different tests (Reverse Transcriptase–PCR [RT-PCR]) issued by public-sector laboratories are also recorded in the system.
SIB: The Integrated Health System (abbreviated as SIB in Persian) was launched to provide health services in the form of health system transformation programs and projects. All the information related to households and the type of health services required in community health centers and health houses is registered in this system. Data about the type of COVID-19 vaccine administered and the intervals between the injection of the first, second, and third doses of the vaccine for both the case and control groups was extracted from this system.
The extracted data covered the period up to March 20, 2021.
Studied population
The case group consisted of patients admitted to hospitals in Guilan Province who had a positive PCR test (n = 19,500), and the control group included people visiting public health centers to get a COVID-19 diagnosis with negative PCR tests (n = 22,586) during the designated interval. The subjects’ vaccination history was extracted from SIB system. The case and control groups were adjusted for sex, 10-year age groups, and the RT-PCR test calendar week (i.e., the number of weeks elapsed since the beginning of the Gregorian month), health care workers and history of positive PCR test results. The purpose of adjusting for the RT-PCR calendar week variable was to eliminate the effect of variations in the epidemic phase, the gradual spread of the vaccination, and other confounding factors in the population. A history of a previous infection detected by PCR could make people more immune during the mentioned months compared to those without a history of positive PCR because of the relative immunity generated. Healthcare workers could have a different situation compared with others because of their priority for getting vaccinated and their greater risk of exposure to the coronavirus. The concerning variants of COVID-19 have played an important role in the pandemic worldwide and in Iran. In Guilan Province, the dominant strain during the fourth wave of the pandemic was the alpha variant, and the dominant strain during the fifth wave was the Delta variant. Note that the peak of the fourth wave was in early April 2021 and the peak of the fifth wave was in August 2021. The type of variant was not examined in our study.
RT-PCR testing is available to everyone in Iran through public, private, and hospital laboratories. This test is approved by the World Health Organization for COVID-19 diagnosis and identifies the SARS-CoV-2 virus based on upper and lower respiratory specimens taken from nasal swabs (nasopharyngeal swabs), throat swabs (oropharyngeal swabs), and sputum. The RT-PCR test was done according to the Espy et al. [23].
Definitions of the outcomes
The outcomes of interest in this study included the moderate form of the disease (temporary admission), severe form (regular admission), critical form (ICU admission), and disease-related death in both the case and control groups.
Temporary admission1: The presence of respiratory symptoms (dyspnea, pain, and pressure in the chest, etc.) with or without a fever, SpO2 of 90-94%, lung involvement <50%.
Regular admission2: respiratory rate >30, SpO2 <90%, lung involvement >50% on the Computed Tomography scan.
ICU admission3: Symptoms of respiratory failure despite non-invasive oxygen therapy, symptoms of septic shock, multiple organ failure.
Death: The occurrence of death in a person with a probable or definite diagnosis of COVID-19 that is clinically ruled to have been caused by COVID-19 without there being other specific non-COVID-19-related causes (e.g., trauma) and the absence of a full recovery period between active COVID-19 and death.
Definition of exposure
The exposure under study comprised of vaccination with the vaccines used in Guilan Province during the study period.
Statistical analysis
Data were analyzed using a logistic regression based on disease outcomes (temporary, regular, and ICU admission, and death) as the dependent variable. Individuals with a positive PCR test constituted the case group, and those with a negative PCR formed the control group. The vaccination status stconsidered an independent variable. Effectiveness was calculated as 1 minus the chances of vaccination in the case group divided by the chances of vaccination in the control group. Adjusted vaccine effectiveness (VE) was calculated using logistic regression. The case and control groups were adjusted for sex, 10-year age groups, and the RT-PCR test calendar week (i.e., the number of weeks elapsed since the beginning of the Gregorian month), Health care workers and history of PCR positive. Vaccination status was classified according to the number of doses of vaccine injected and the post-vaccination interval.
The interval after the first dose was <21 days and ≥21 days, and the interval after the second dose was 1-30 days, 30-60 days, 60-90 days, 90-120 days, 120-150 days, and ≥151 days, and booster dose. The statistical analysis of the data was performed in STATA 16, SE software.
Results
This study was conducted from May 22 to December 21, 2021. After applying the exclusion criteria (unspecified PCR test results and having received mixed vaccines), 42,084 people entered the study. Of these, 19,500 (46%) belonged to the case and 22,586 (54%) to the control groups. Among those with a positive PCR test (case group), the number of women was more than men (56%), but among those with a negative PCR test (control group), the number of men and women was similar (50.0%). The characteristics of the case and control groups are presented in Table 1 . The results of our study on the effectiveness of the vaccines used were as follows:
Table 1.
Characteristics of population study.
| Characteristics | PCR test positive, cases (n = 19,500) | PCR test negative, controls (n = 22,585) | |
|---|---|---|---|
| Age | P-value | ||
| Median (IQR) | 53 (25) | 37 (22) | |
| Age group (years) | |||
| 0-9 years | 563 (2.9%) | 448 (2.0%) | <0.001 |
| 10-19 years | 239 (1.2%) | 4%) | |
| 20-29 years | 1026 (5.3%) | .4%) | |
| 30-39 years | 2800 (14.4%) | .4%) | |
| 40-49 years | 3495 (17.9%) | .5%) | |
| 50-59 years | 4115 (21.1%) | .0%) | |
| 60-69 years | 3857 (19.8%) | 3%) | |
| ≤70 years | 3404 (17.5%) | 928 (4.1%) | |
| Gender | |||
| Male | 8613 (44.2%) | 11,290 (50.0%) | <0.001 |
| Female | 10,886 (55.8%) | 11,295 (50.0%) | |
| Health care workers | |||
| No | 19,348 (99.2%) | 21,524 (95.3%) | <0.001 |
| Yes | 151 (0.8%) | 1061(4.7%) | |
| History of PCR positive | |||
| No | 19,377 (99.4%) | 22,442 (99.4%) | 0.923 |
| Yes | 122 (0.6%) | 143 (0.6%) | |
| Vaccination status | |||
| Non-vaccinated | 13,312 (68.3%) | 15,676 (69.4%) | < 0.001 |
| Vaccinated | |||
| Single dose, <21 days | 1740 (8.9%) | .6%) | |
| Single dose, ≥21 days | 2065 (10.6%) | 1%) | |
| Two doses, within 1-30 days | 671 (3.4%) | 3%) | |
| Two doses, within 31-60 days | 667 (3.4%) | 9%) | |
| Two doses, within 61-90 days | 479 (2.5%) | 827(3.7%) | |
| Two doses, within 91-120 days | 339 (1.7%) | 651(2.9%) | |
| Two doses, within 121-150 days | 127 (0.7%) | .1%) | |
| Two doses, ≥ 151 days | 73 (0.4%) | .3%) | |
| Third dose | 26 (0.1%) | 158 (0.7%) | |
| Hospitalization status | |||
| Test-negative | 0 (0%) | 22585 (100%) | < 0.001 |
| Temporary admissiona | 2699 (13%) | 0 (0%) | |
| Regular admissionb | 14638 (75%) | 0 (0%) | |
| Intensive care unit admissionc | %) | 0 (0%) | |
| Death | 1887 (10%) | 0 (0%) |
PCR, polymerase chain reaction.
SpO2 90-94%, lung involvement < 50.
SpO2 < 90%, RR>30, Lung involvement > 50.
Septic shock, multiple organ failure.
AstraZeneca
The odds of temporary hospital admission in people who had received two doses of the vaccine during the 31-60 days from their second dose until their hospital admission compared to the unvaccinated people was 0.03 (CI: 0.005-0.25), suggesting an estimated adjusted effectiveness of 97% in the group. The odds of regular hospital admission (general ward) in people who had received two doses of the vaccine during the 121-150 days from their second dose until admission compared to the unvaccinated was 0.02 (CI: 0.01-0.06), with the adjusted effectiveness estimated at 98%. The odds of ICU admission in patients who had received two doses did not show a statistically significant difference with the unvaccinated population. The odds of death in people who had received two doses of the vaccine compared to the unvaccinated 121-150 days after the second dose was 0.08 (CI: 0.01-0.59), suggesting an estimated adjusted effectiveness of about 92%.
Sinopharm
The odds of temporary and regular admission for people who had received two doses of the vaccine from whose second dose ≤151 days elapsed until the time of their hospital admission were respectively 0.05 (CI: 0.006-0.33) and 0.15 (CI: 0.09-0.23) compared with the unvaccinated individuals, and the adjusted effectiveness in these groups was estimated as 95% and 85%, respectively. The odds of ICU admission for people who had received two doses during the 61-90 days from their second dose to admission compared with the unvaccinated individuals was 0.45 (CI: 0.27-0.76), and the adjusted effectiveness in these groups was estimated as 55%. The odds of death in people who had received two doses during the 91-120 days from their second dose to admission compared with the unvaccinated individuals was 0.44 (CI: 0.29-0.67), suggesting an adjusted effectiveness of about 56%.
COVIran Barekat
The odds of temporary and regular admission in people who had received two doses of the vaccine during the 61-90 days from their second dose until the time of their hospital admission were respectively 0.03 (CI: 0.004-0.24) and 0.05 (CI: 0.03-0.09) compared to the unvaccinated people, with the adjusted effectiveness estimated at 97% and 95%, respectively. The odds of death in people who had received two doses of the vaccine 61-90 days after the administration of the second dose was 0.11 (CI: 0.02-0.45) compared to the unvaccinated people, with an adjusted effectiveness of about 89%.
Sputnik V
The odds of temporary and regular admission in people who had received two doses of the vaccine from whose second dose ≥151 days elapsed until the time of hospital admission were respectively 0.05 (CI: 0.01-0.21) and 0.07 (CI: 0.04-0.12) compared with the unvaccinated people, with the adjusted effectiveness estimated at 95% and 93%, respectively. The odds of death and ICU admission in people who had received two doses of the vaccine compared with the unvaccinated people did not show a statistically significant difference.
Bharat
The odds of regular admission in those who had received two doses of the vaccine from whose second dose ≤151 days elapsed until admission was 0.43 (CI: 0.005-0.32) compared to the unvaccinated people, with the adjusted effectiveness estimated at 57%.
The odds ratio of one in some subgroups was because of their small sample size. Moreover, less than 10% of the population had been given a booster (third) dose of vaccines in Guilan Province at the time this study was conducted. Also, people who had received a different vaccine as their booster dose (The third vaccine was not the same as the first and second vaccines) were excluded from the study due to their small sample size (n = 17). Table 1 shows the characteristics of the study population, Table 2, Table 3 present the results of the analysis performed to evaluate the effectiveness of the vaccines based on the severity of the disease in the inpatients.
Table 2.
Effectiveness of AstraZeneca against hospitalized patients in Guilan Province (Iran) (comparison of temporary admission, regular admission, intensive care unit admission and death cases with test-negative controls).
| Vaccination status | Cases N (%) | Controls N (%) | Unadjusted odds ratio (95% CI) | Adjusted odds ratio (95% CI) | Adjusteda vacine effectiveness (95% CI) | P-value |
|---|---|---|---|---|---|---|
| Temporary admission | ||||||
| Unvaccinated | 1881(0.94) | 15676(0.92) | Reference | Reference | Reference | |
| Single dose, <21 days | 34(0.01) | 61(0.003) | 2.14(1.49-3.08) | 1.67 (1.15- 2.41) | - | <0.001 |
| Single dose, ≥21 days | 64(0.03) | 676(0.03) | 0.79(0.61-1.02) | 0.47(0.36- 0.62) | 0.53 (0.38-0.64) | |
| Two doses, within 1-30 days | 9(0.004) | 201(0.01) | 0.44(0.22-0.86) | 0.22(0.11-0.44) | 0.78 (0.56-0.89) | |
| Two doses, within 31-60 days | 1(0.0005) | 105(0.006) | 0.09(0.01-0.71) | 0.03(0.005- 0.25) | 0.97 (0.75-0.995) | |
| Two doses, within 61-90 days | 0 | 54(0.003) | 1 | 1 | - | - |
| Two doses, within 91-120 days | 2(0.001) | 89(0.005) | 0.24 (0.06-0.98) | 0.07(0.01-0.31) | 0.93(0.69-0.99) | <0.001 |
| Two doses, within 121-150 days | 0 | 79(0.004) | 1 | 1 | - | - |
| Two doses, ≥ 151 days | 0 | 11(0.0006) | 1 | 1 | - | |
| Third dose | 0 | 11(0.0006) | 1 | 1 | - | |
| Regular admission | ||||||
| Unvaccinated | 10083(0.93) | 15676(0.92) | Reference | Reference | Reference | |
| Single dose, <21 days | 147(0.01) | 61(0.003) | 2.39(1.87- 3.06) | 1.47(1.14- 1.90) | - | <0.001 |
| Single dose, ≥ 21 days | 396(0.03) | 676(0.03) | 0.89 (0.79- 1.01) | 0.42(0.36- 0.48) | 0.58(0.52-0.64) | |
| Two doses, within 1-30 days | 77(0.007) | 201(0.01) | 0.64 (0.49- 0.83) | 0.27 (0.2- 0.36) | 0.73(0.64-0.8) | |
| Two doses, within 31-60 days | 32(0.002) | 105(0.006) | 0.52(0.35- 0.77) | 0.13(0.08- 0.2) | 0.87(0.8-0.92) | |
| Two doses, within 61-90 days | 32(0.002) | 54(0.003) | 1.03(0.67- 1.59) | 0.22(0.13- 0.35) | 0.78(0.65-0.87) | |
| Two doses, within 91-120 days | 18(0.001) | 89(0.005) | 0.33(0.20- 0.54) | 0.06(0.03- 0.11) | 0.94(0.89-0.97) | |
| Two doses, within 121-150 days | 5(0.0004) | 79(0.004) | 0.11(0.04-0.27) | 0.02(0.01- 0.06) | 0.98(0.94-0.99) | |
| Two doses, ≥ 151 days | 2(0.0001) | 11(0.0006) | 0.34(0.07- 1.53) | 0.10(0.02- 0.49) | 0.9 (0.51-0.98) | |
| Third dose | 1(0.00009) | 11(0.0006) | 0.17(0.02- 1.31) | 0.06(0.008-0. 54) | 0.94(0.46-0.992) | |
| Intensive care unit admission | ||||||
| Unvaccinated | 363(0.91) | 15676(0.92) | Reference | Reference | Reference | 0.191 |
| Single dose, <21 days | 2(0.005) | 61(0.003) | 0.60(0.15- 2.44) | 0.39 (0.09- 1.59) | 0.61(-0.59-0.91) | 0.033 |
| Single dose, ≥ 21 days | 19(0.04) | 676(0.03) | 1.24(0.78- 1.97) | 0.59(0.36- 0.95) | 0.41(0.05-0.64) | 0.062 |
| Two doses, within 1-30 days | 3(0.007) | 201(0.01) | 0.79(0.25- 2.47) | 0.33(0.1- 1.05) | 0.67 (-0.05-0.9) | 0.167 |
| Two doses, within 31-60 days | 3(0.007) | 105(0.006) | 1.65(0.52- 5.21) | 0.43(0.13- 1.41) | 0.57(-0.41-0.87) | 0.097 |
| Two doses, within 61-90 days | 1(0.002) | 54(0.003) | 0.88(0.12- 6.37) | 0.18(0.02- 1.35) | 0.82(-0.35-0.98) | 0.793 |
| Two doses, within 91-120 days | 6(0.01) | 89(0.005) | 4.14(1.81- 9.49) | 0.88(0.37- 2.13) | 0.12(-1.13-0.63) | 0.191 |
| Two doses, within 121-150 days | 0 | 79(0.004) | 1 | 1 | - | |
| Two doses, ≥ 151 days | 0 | 11(0.0006) | 1 | 1 | - | |
| Third dose | 0 | 11(0.0006) | 1 | 1 | - | |
| Death | ||||||
| Unvaccinated | 1204(0.9) | 15676(0.92) | Reference | Reference | Reference | |
| Single dose, <21 days | 20(0.01) | 61(0.003) | 1.90(1.20-3.01) | 1.10(0.69-1.77) | - | |
| Single dose, ≥ 21 days | 78(0.05) | 676(0.03) | 1.56(1.23-1.98) | 0.63(0.49-0.81) | 0.37(0.19-0.51) | <0.001 |
| Two doses, within 1-30 days | 16(0.01) | 201(0.01) | 1.29(0.77-2.14) | 0.51(0.3-0.87) | 0.49(0.13-0.7) | 0.011 |
| Two doses, within 31-60 days | 5(0.003) | 105(0.006) | 0.81(0.33-1.99) | 0.20(0.08-0.52) | 0.8 (0.48-0.92) | 0.001 |
| Two doses, within 61-90 days | 4(0.003) | 54(0.003) | 1.07(0.39-2.92) | 0.16(0.06-0.46) | 0.84(0.54-0.94) | 0.001 |
| Two doses, within 91-120 days | 4(0.003) | 89(0.005) | 0.79(0.29-2.15) | 0.13(0.04-0.38) | 0.87(0.62-0.96) | <0.001 |
| Two doses, within 121-150 days | 1(0.0007) | 79(0.004) | 0.25(0.03-1.86) | 0.08(0.01-0.59) | 0.92(0.48-0.99) | 0.008 |
| Two doses, ≥ 151 days | 0 | 11(0.0006) | 1 | 1 | ||
| Third dose | 0 | 11(0.0006) | 1 | 1 | ||
Adjusted for: Age group, sex, week sampling polymerase chain reaction (PCR). Health care workers, History of PCR positive.
Table 3.
Effectiveness of Sinopharm, COVIran Barekat, Sputnik V and Bharat against hospitalized patients in Guilan Province (Iran) (comparison of temporary admission, regular admission, ICU admission and death cases with test-negative controls).
| Sinopharm | ||||||
|---|---|---|---|---|---|---|
| Vaccination status | Cases N (%) |
Controls N (%) |
Unadjusted OR (95% CI) |
Adjusted OR (95% CI) |
Adjusteda VE (95% CI) |
P-value |
| Temporary admission | ||||||
| Unvaccinated | 1881(0.76) | 15676(0.78) | Reference | Reference | Reference | |
| Single dose, <21 days | 223(0.09) | 456(0.02) | 2.07(1.78-2.40) | 1.60(1.37-1.86) | - | - |
| Single dose, ≥ 21 days | 196(0.07) | 796(0.03) | 1.47(1.26-1.72) | 0.98(0.83-1.15) | 0.02(-0.15-0.17) | 0.829 |
| Two doses, within 1-30 days | 56(0.02) | 892(0.04) | 0.59(0.45-0.78) | 0.38(0.28-0.5) | 0.62(0.5-0.72) | <0.001 |
| Two doses, within 31-60 days | 46(0.01) | 1068(0.05) | 0.41(0.30-0.56) | 0.22(0.16-0.31) | 0.78(0.69-0.84) | |
| Two doses, within 61-90 days | 42(0.01) | 481(0.02) | 0.71(0.52-0.98) | 0.36(0.26-0.5) | 0.64(0.5-0.74) | |
| Two doses, within 91-120 days | 13(0.005) | 300(0.01) | 0.35(0.20-0.60) | 0.14(0.08-0.25) | 0.86(0.75-0.92) | |
| Two doses, within 121-150 days | 3(0.001) | 92(0.004) | 0.22(0.07-0.70) | 0.09(0.03-0.3) | 0.91(0.7-0.97) | |
| Two doses, ≥ 151 days | 1(0.0004) | 82(0.004) | 0.11(0.01-0.81) | 0.05(0.006-0.33) | 0.95(0.67-0.994) | 0.002 |
| Third dose | 0(0) | 83(0.004) | 1 | 1 | - | |
| Regular admission | ||||||
| Unvaccinated | 10083(0.75) | 15676(0.78) | Reference | Reference | Reference | |
| Single dose, <21 days | 946(0.07) | 456(0.02) | 2.14(1.94-2.36) | 1.21(1.09-1.34) | - |
<0.001 |
| Single dose, ≥ 21 days | 964(0.07) | 796(0.03) | 1.58(1.44-1.72) | 0.78(0.71-0.86) | 0.22(0.14-0.29) | |
| Two doses, within 1-30 days | 387(0.02) | 892(0.04) | 0.70(0.62-0.79) | 0.36(0.32-0.41) | 0.64(0.59-0.68) | |
| Two doses, within 31-60 days | 433(0.03) | 1068(0.05) | 0.67(0.60-0.75) | 0.29(0.25-0.33) | 0.71(0.68-0.75) | |
| Two doses, within 61-90 days | 312(0.02) | 481(0.02) | 1.02(0.88-1.17) | 0.33(0.28-0.39) | 0.67(0.61-0.72) | |
| Two doses, within 91-120 days | 194(0.01) | 300(0.01) | 1.03(0.86-1.22) | 0.23(0.19-0.28) | 0.77(0.72-0;81) | |
| Two doses, within 121-150 days | 79(0.005) | 92(0.004) | 1.27(0.95-1.70) | 0.28(0.20-0.38) | 0.74(0.64-0.81) | |
| Two doses, ≥ 151 days | 32(0.002) | 82(0.004) | 0.62(0.41-0.93) | 0.15(0.09-0.23) | 0.85(0.77-0.91) | |
| Third dose | 14(0.001) | 83(0.004) | 0.28(0.16-0.49) | 0.04(0.02-0.08) | 0.96(0.92-0.98) | |
| ICU admission | ||||||
| Unvaccinated | 363(0.64) | 15676(0.78) | Reference | Reference | Reference | |
| Single dose, <21 days | 29(0.05) | 456(0.02) | 1.31(0.89-1.92) | 0.76 (0.51-1.1) | 0.24(-0.1-0.49) | 0.165 |
| Single dose, ≥ 21 days | 46(0.08) | 796(0.03) | 1.76(1.29-2.39) | 0.84(0.6-1.16) | 0.16(-0.16-0.4) | 0.298 |
| Two doses, within 1-30 days | 25(0.04) | 892(0.04) | 1.42(0.94-2.13) | 0.72(0.47-1.17) | 0.28(-0.17-0.53) | 0.142 |
| Two doses, within 31-60 days | 37(0.06) | 1068(0.05) | 1.82(1.29-2.56) | 0.75(0.52-1.09) | 0.25(-0.09-0.48) | 0.138 |
| Two doses, within 61-90 days | 17(0.03) | 481(0.02) | 1.54(0.94-2.52) | 0.45(0.27-0.76) | 0.55(0.24-0.73) | 0.003 |
| Two doses, within 91-120 days | 24(0.04) | 300(0.01) | 3.61(2.37-5.51) | 0.73(0.45-1.17) | 0.27(-0.17-0.55) | 0.195 |
| Two doses, within 121-150 days | 8(0.01) | 92(0.004) | 3.37(1.65-6.89) | 0.61(0.29-1.3) | 0.39(-0.3-0.71) | 0.206 |
| Two doses, ≥ 151 days | 6(0.01) | 82(0.004) | 3.87(1.69-8.85) | 0.74(0.31-1.77) | 0.26(-0.77-0.69) | 0.512 |
| Third dose | 8(0.01) | 83(0.004) | 6.37(3.07-13.19) | 1.001(0.46-2.17) | - | - |
| Death | ||||||
| Unvaccinated | 1213(0.71) | 15676(0.78) | Reference | Reference | Reference | |
| Single dose, <21 days | 142(0.08) | 456(0.02) | 1.99(1.66-2.39) | 1.08(0.89-1.30) | - | - |
| Single dose, ≥ 21 days | 130(0.07) | 796(0.03) | 1.50(1.24-1.81) | 0.83(0.68-1.01) | 0.17(-0.01-0.32) | 0.070 |
| Two doses, within 1-30 days | 59(0.03) | 892(0.04) | 0.99(0.76-1.30) | 0.66(0.5-0.87) | 0.34(0.13-0.5) | 0.003 |
| Two doses, within 31-60 days | 65(0.03) | 1068(0.05) | 0.94(0.73-1.22) | 0.59(0.45-0.77) | 0.41(0.23-0.55) | <0.001 |
| Two doses, within 61-90 days | 35(0.02) | 481(0.02) | 0.94(0.66-1.33) | 0.46(0.32-0.65) | 0.54(0.35-0.68) | |
| Two doses, within 91-120 days | 26(0.01) | 300(0.01) | 1.14(0.76-1.70) | 0.44(0.29-0.67) | 0.56(0.33-0.71) | |
| Two doses, within 121-150 days | 16(0.009) | 92(0.004) | 2.04(1.22-3.42) | 0.63(0.37-1.07) | 0.37(-0.07-0.63) | 0.092 |
| Two doses, ≥ 151 days | 8(0.004) | 82(0.004) | 1.52(0.74-3.12) | 0.67(0.31-1.4) | 0.33(-0. 4-0.69) | 0.290 |
| Third dose | 5(0.002) | 83(0.004) | 1.12(0.45-2.75) | 0.42(0.17-1.06) | 0.58(-0.06-0.83) | 0.069 |
| COVIran Barekat | ||||||
| Vaccination status | Cases N (%) |
Controls N (%) |
Unadjusted OR (95% CI) |
Adjusted OR (95% CI) |
Adjusteda VE (95% CI) |
P-value |
| Temporary admission | ||||||
| Unvaccinated | 1881(0.95) | 15676(0.97) | Reference | Reference | Reference | |
| Single dose, <21 days | 40(0.02) | 38(0.002) | 2.66(1.89-3.75) | 2.12(1.50-2.99) | - | - |
| Single dose, ≥ 21 days | 35(0.01) | 71(0.004) | 2.28(1.59-3.26) | 1.31(0.90-1.89) | - | - |
| Two doses, within 1-30 days | 11(0.005) | 76(0.004) | 1.44(0.77-2.68) | 0.71(0.38-1.34) | 0.29(-0.34-0.62) | 0.299 |
| Two doses, within 31-60 days | 1(0.0005) | 81(0.005) | 0.12(0.01-0.87) | 0.04(0.006-0.32) | 0.96(0.68-0.994) | 0.002 |
| Two doses, within 61-90 days | 1(0.0005) | 111(0.006) | 0.11(0.01-0.79) | 0.03(0.004-0.24) | 0.97(0.76-0.996) | 0.001 |
| Two doses, within 91-120 days | 0 | 56(0.003) | 1 | 1 | - | |
| Two doses, within 121-150 days | 0 | 2(0.0001) | 1 | 1 | - | |
| Two doses, ≥ 151 days | 0 | 0 | ||||
| Third dose | 0 | 0 | - | |||
| Regular admission | ||||||
| Unvaccinated | 10083(0.96) | 15676(0.97) | Reference | Reference | Reference | |
| Single dose, <21 days | 152(0.01) | 38(0.002) | 2.73(2.13-3.51) | 1.59(1.22-2.06) | - | |
| Single dose, ≥ 21 days | 129(0.01) | 71(0.004) | 1.90(1.48-2.43) | 0.78(0.6-1.01) | 0.22(-0.01-0.4) | 0.063 |
| Two doses, within 1-30 days | 32(0.003) | 76(0.004) | 0.67(0.44-1.00) | 0.25(0.16-0.38) | 0.75(0.62-0.84) | <0.001 |
| Two doses, within 31-60 days | 33(0.003) | 81(0.005) | 0.71(0.48-1.07) | 0.18(0.12-0.27) | 0.82(0.73-0.88) | <0.001 |
| Two doses, within 61-90 days | 17(0.001) | 111(0.006) | 0.27(0.16-0.46) | 0.05(0.03-0.09) | 0.95(0.91-0.97) | <0.001 |
| Two doses, within 91-120 days | 15(0.001) | 56(0.003) | 0.47(0.27-0.84) | 0.08(0.04-0.14) | 0.92(0.86-0.96) | <0.001 |
| Two doses, within 121-150 days | 0 | 2(0.0001) | 1 | 1 | - | |
| Two doses, ≥ 151 days | 0 | 0 | ||||
| Third dose | 0 | 0 | ||||
| ICU admission | ||||||
| Unvaccinated | 363(0.96) | 15676(0.97) | Reference | Reference | Reference | |
| Single dose, <21 days | 5(0.01) | 38(0.002) | 1.57(0.64-3.82) | 0.97(0.4-2.39) | 0.03(-1.39-0.6) | 0.960 |
| Single dose, ≥ 21 days | 3(0.007) | 71(0.004) | 0.93(0.29-2.93) | 0.4 (0.12-1.28) | 0.6 (-0.28-0.88) | 0.126 |
| Two doses, within 1-30 days | 0 | 76(0.004) | 1 | 1 | - | |
| Two doses, within 31-60 days | 2(0.005) | 81(0.005) | 1.34(0.33-5.47) | 0.39(0.09-1.63) | 0.61(-0.61-0.91) | 0.2 |
| Two doses, within 61-90 days | 2(0.005) | 111(0.006) | 1.22(0.30-4.95) | 0.29(0.07-1.22) | 0.71(-0.22-0.93) | 0.090 |
| Two doses, within 91-120 days | 3(0.007) | 56(0.003) | 3.33(1.04-10.62) | 0.65(0.2-2.16) | 0.35(-1.16-0.8) | 0.490 |
| Two doses, within 121-150 days | 0 | 2(0.0001) | 1 | 1 | - | |
| Two doses, ≥ 151 days | 0 | 0 | ||||
| Third dose | 0 | 0 | ||||
| Death | ||||||
| Unvaccinated | 1204(0.95) | 15676(0.97) | Reference | Reference | Reference | |
| Single dose, <21 days | 24(0.01) | 38(0.002) | 2.38(1.56-3.64) | 1.19(0.77-1.84) | - | |
| Single dose, ≥ 21 days | 19(0.01) | 71(0.004) | 1.84(1.15-2.96) | 0.73(0.45-1.19) | 0.27(-0.19-0.55) | 0.209 |
| Two doses, within 1-30 days | 3(0.002) | 76(0.004) | 0.58(0.18-1.84) | 0.27(0.08-0.88) | 0.73(0.12-0.92) | 0.030 |
| Two doses, within 31-60 days | 2(0.001) | 81(0.005) | 0.39(0.09-1.59) | 0.12(0.03-0.52) | 0.88(0.48-0.97) | 0.004 |
| Two doses, within 61-90 days | 2(0.001) | 111(0.006) | 0.35(0.08-1.44) | 0.11(0.02-0.45) | 0.89(0.55-0.98) | 0.002 |
| Two doses, within 91-120 days | 1(0.0007) | 56(0.003) | 0.31(0.04-2.27) | 0.07(0.01-0.54) | 0.93(0.46-0.99) | 0.011 |
| Two doses, within 121-150 days | 0 | 2(0.0001) | 1 | 1 | ||
| Two doses, ≥ 151 days | 0 | 0 | ||||
| Third dose |
0 | 0 | ||||
| Sputnik V | ||||||
| Vaccination status | Cases N (%) |
Controls N (%) |
Unadjusted OR (95% CI) |
Adjusted OR (95% CI) |
Adjusteda VE (95% CI) |
P-value |
| Temporary admission | ||||||
| Unvaccinated | 1881(0.98) | 15673(0.95) | Reference | Reference | Reference | |
| Single dose, <21 days | 2(0.001) | 30(0.001) | 0.73(0.17-3.06) | 0.71(0.17-3.01) | 0.29(-2.01-0.83) | 0.651 |
| Single dose, ≥ 21 days | 2(0.001) | 49(0.002) | 0.49(0.12-2.03) | 0.42(0.1-1.77) | 0.58(-0.77-0.9) | 0.242 |
| Two doses, within 1-30 days | 1(0.0005) | 39(0.002) | 0.32(0.04-2.32) | 0.24(0.03-1.77) | 0.76(-0.77-0.97) | 0.162 |
| Two doses, within 31-60 days | 2(0.001) | 76(0.004) | 0.30(0.07-1.23) | 0.26(0.06-1.09) | 0.74(-0.09-0.94) | 0.067 |
| Two doses, within 61-90 days | 3(0.001) | 152(0.009) | 0.26(0.08-0.82) | 0.26(0.08-0.84) | 0.74(0.16-0.92) | 0.025 |
| Two doses, within 91-120 days | 11(0.005) | 169(0.01) | 0.84(0.46-1.55) | 0.8 (0.42-1.50) | 0.2 (-0.5-0.58) | 0.492 |
| Two doses, within 121-150 days | 6(0.003) | 52(0.003) | 1.37(0.59-3.17) | 0.84(0.36-1.99) | 0.16(-0.99-0.64) | 0.706 |
| Two doses, ≥ 151 days | 2(0.001) | 176(0.01) | 0.14(0.03-0.58) | 0.05(0.01-0.21) | 0.95(0.79-0.99) | <0.001 |
| Third dose | 0 | 44(0.002) | 1 | 1 | - | |
| Regular admission | ||||||
| Unvaccinated | 10083(0.99) | 15673(0.95) | Reference | Reference | Reference | |
| Single dose, <21 days | 7(0.0006) | 30(0.001) | 0.38(0.17-0.87) | 0.44(0.19-1.04) | 0.56(-0.04-0.81) | 0.064 |
| Single dose, ≥ 21 days | 7(0.0006) | 49(0.002) | 0.24(0.11-0.54) | 0.2 (0.08-0.45) | 0.8 (0.55-0.92) | <0.001 |
| Two doses, within 1-30 days | 5(0.0004) | 39(0.002) | 0.22(0.09-0.57) | 0.16(0.06-0.43) | 0.84(0.57-0.94) | |
| Two doses, within 31-60 days | 17(0.001) | 76(0.004) | 0.39(0.23-0.67) | 0.38(0.22-0.68) | 0.62(0.32-0.78) | |
| Two doses, within 61-90 days | 13(0.001) | 152(0.009) | 0.15(0.08-0.27) | 0. 2 (0.11-0.37) | 0.8 (0.63-0.89) | |
| Two doses, within 91-120 days | 14(0.001) | 169(0.01) | 0.14(0.08-0.24) | 0.15(0.08-0.28) | 0.85 (0.72-0.92) | |
| Two doses, within 121-150 days | 10(0.0009) | 52(0.003) | 0.31(0.16-0.62) | 0. 21(0.10-0.43) | 0.79(0.57-0.9) | |
| Two doses, ≥ 151 days | 17(0.001) | 176(0.01) | 0.17(0.10-0.28) | 0.07(0.04-0.12) | 0.93(0.88-0.96) | |
| Third dose | 0 | 44(0.002) | ||||
| ICU admission | ||||||
| Unvaccinated | 363(0.98) | 15673(0.95) | Reference | Reference | Reference | |
| Single dose, <21 days | 0 | 30(0.001) | 1 | 1 | - | |
| Single dose, ≥ 21 days | 0 | 49(0.002) | 1 | 1 | - | |
| Two doses, within 1-30 days | 1(0.002) | 39(0.002) | 1.75(0.24-12.74) | 1.41(0.18-10.54) | - | |
| Two doses, within 31-60 days | 0 | 76(0.004) | 1 | 1 | - | |
| Two doses, within 61-90 days | 0 | 152(0.009) | 1 | 1 | - | |
| Two doses, within 91-120 days | 1(0.002) | 169(0.01) | 0.40(0.05-2.8) | 0.49(0.06-3.58) | 0.51(-2.58-0.94) | 0.677 |
| Two doses, within 121-150 days | 0 | 52(0.003) | 1 | 1 | - | |
| Two doses, ≥ 151 days | 4(0.01) | 176(0.01) | 1.60(0.59-4.35) | 0.82(0.29-2.36) | 0.18(-1.36-0.71) | 0.290 |
| Third dose | 0 | 44(0.002) | 1 | 1 | - | |
| Death | ||||||
| Unvaccinated | 1204(0.98) | 15673(0.95) | Reference | Reference | Reference | |
| Single dose, <21 days | 3(0.002) | 30(0.001) | 1.82(0.56-5.90) | 2.81(0.80-9.79) | - | |
| Single dose, ≥ 21 days | 2(0.001) | 49(0.002) | 0.79(0.19-3.26) | 0.62(0.14-2.67) | 0.38(-1.67-0.86) | 0.522 |
| Two doses, within 1-30 days | 0 | 39(0.002) | 1 | 1 | - | |
| Two doses, within 31-60 days | 3(0.002) | 76(0.004) | 0.73(0.23-2.32) | 0.75(0.22-2.49) | 0.25(-1.49-0.78) | 0.643 |
| Two doses, within 61-90 days | 0 | 152(0.009) | 1 | 1 | - | |
| Two doses, within 91-120 days | 5(0.004) | 169(0.01) | 0.59(0.24-1.45) | 0.71(0.27-1.82) | 0.29(-0.82-0.73) | 0.480 |
| Two doses, within 121-150 days | 1(0.0008) | 52(0.003) | 0.33(0.04-2.44) | 0.24(0.03-1.87) | 0.76(-0.87-0.97) | 0.175 |
| Two doses, ≥ 151 days | 1(0.0008) | 176(0.01) | 0.11(0.01-0.82) | 0.07(0.009-0.53) | 0.93(0.47-0.991) | 0.010 |
| Third dose |
0 | 44(0.002) | 1 | 1 | - | |
| Bharat | ||||||
| Vaccination status | Cases N (%) |
Controls N (%) |
Unadjusted OR (95% CI) |
Adjusted OR (95% CI) |
Adjusteda VE (95% CI) |
P-value |
| Temporary admission | ||||||
| Unvaccinated | 1881(0.99) | 15676(0.99) | Reference | Reference | Reference | |
| Single dose, <21 days | 1(0.0005) | 1(0.00006) | 4.80(0.49-46.18) | 3.15(0.31-31.21) | - | - |
| Single dose, ≥ 21 days | 1(0.0005) | 6(0.0003) | 2.05(0.25-16.73) | 1.90(0.22-16.03) | - | - |
| Two doses, within 1-30 days | 0 | 2(0.0001) | 1 | 1 | - | |
| Two doses, within 31-60 days | 0 | 5(0.0003) | 1 | 1 | - | |
| Two doses, within 61-90 days | 0 | 37(0.002) | 1 | 1 | - | |
| Two doses, within 91-120 days | 12(0.006) | 33(0.002) | 4.21(2.21-8.03) | 4.55(2.30-8.97) | - | - |
| Two doses, within 121-150 days | 1(0.0005) | 8(0.0005) | 1.80(0.22-14.40) | 1.34(0.16-10.89) | - | - |
| Two doses, ≥ 151 days | 0 | 33(0.002) | 1 | 1 | - | |
| Third dose | 0 | 7(0.0004) | 1 | 1 | - | |
| Regular admission | ||||||
| Unvaccinated | 10083(0.99) | 15676(0.99) | Reference | Reference | Reference | |
| Single dose, <21 days | 2(0.0001) | 1(0.00006) | 1.87(0.26-13.30) | 0.99(0.13-7.14) | 0.01(-6.14-0.87) | 0.992 |
| Single dose, ≥ 21 days | 1(0.00009) | 6(0.0003) | 0.26(0.03-2.17) | 0.29(0.03-2.52) | 0.71(-1.52-0.97) | 0.263 |
| Two doses, within 1-30 days | 1(0.00009) | 2(0.0001) | 0.93(0.08-10.33) | 0.59(0.04-7.08) | 0.41(-6.08-0.96) | 0.680 |
| Two doses, within 31-60 days | 0 | 5(0.0003) | 1 | 1 | - | |
| Two doses, within 61-90 days | 4(0.0003) | 37(0.002) | 0.20(0.07-0.56) | 0.45(0.15-1. 33) | 0.55(-0.33-0.85) | 0.152 |
| Two doses, within 91-120 days | 7(0.0006) | 33(0.002) | 0.28(0.12-0.63) | 0.43(0.18-1.02) | 0.57(-0.02-0.82) | 0.057 |
| Two doses, within 121-150 days | 0 | 8(0.0005) | 1 | 1 | - | |
| Two doses, ≥ 151 days | 1(0.00009) | 33(0.002) | 0.05(0.007-0.41) | 0.04 (0.005-0.32) | 0.96(0.68-0.995) | 0.002 |
| Third dose | 0 | 7(0.0004) | 1 | 1 | - | |
| ICU admission | ||||||
| Unvaccinated | 363(0.99) | 15676(0.99) | Reference | Reference | Reference | |
| Single dose, <21 days | 0 | 1(0.00006) | 1 | 1 | - | |
| Single dose, ≥ 21 days | 0 | 6(0.0003) | 1 | 1 | - | |
| Two doses, within 1-30 days | 0 | 2(0.0001) | 1 | 1 | - | |
| Two doses, within 31-60 days | 0 | 5(0.0003) | 1 | 1 | - | |
| Two doses, within 61-90 days | 0 | 37(0.002) | 1 | 1 | - | |
| Two doses, within 91-120 days | 1(0.002) | 33(0.002) | 1.51(0.20-10.99) | 2.31(0.30-17.08) | - | - |
| Two doses, within 121-150 days | 0 | 8(0.0005) | 1 | 1 | - | |
| Two doses, ≥ 151 days | 0 | 33(0.002) | 1 | 1 | - | |
| Third dose | 0 | 7(0.0004) | 1 | 1 | - | |
| Death | ||||||
| Unvaccinated | 1204(0.99) | 15676(0.99) | Reference | Reference | Reference | |
| Single dose, <21 days | 0 | 1(0.00006) | 1 | 1 | - | |
| Single dose, ≥ 21 days | 0 | 6(0.0003) | 1 | 1 | - | |
| Two doses, within 1-30 days | 0 | 2(0.0001) | 1 | 1 | - | |
| Two doses, within 31-60 days | 1(0.0008) | 5(0.0003) | 4.61(0.53-39.52) | 5.15(0.42-62.20) | - | - |
| Two doses, within 61-90 days | 0 | 37(0.002) | 1 | 1 | - | |
| Two doses, within 91-120 days | 1(0.0008) | 33(0.002) | 0.44(0.06-3.21) | 0.96(0.12-7.71) | 0.04(-6.71-0.79) | 0.976 |
| Two doses, within 121-150 days | 0 | 8(0.0005) | 1 | 1 | - | |
| Two doses, ≥ 151 days | 0 | 33(0.002) | 1 | 1 | - | |
| Third dose | 0 | 7(0.0004) | 1 | 1 | - | |
ICU, intensive care unit; VE, vaccine effectiveness.
Adjusted for: Age group, sex, week sampling ploymerase chain reaction (PCR), Health care workers.History of PCR-positive test results.
Figure 1 presents the vaccination coverage in Guilan Province separately for first, second, and third doses.
Figure 1.
The vaccination coverage in Guilan province separately for first, second, and third doses.
This study was conducted previous significant uptake of booster doses (<10% had a booster dose in the overall population and <1% in the study population). The net vaccination coverage in the target population of Guilan (n = 2,235,600) has thus been 84% for the first and 75% for the second doses.
Figure 2 presents the trend of hospital admission in Guilan Province during the study during this period, the alpha and Delta variants were circulating and the increase of hospitalization cases in the province from July 01, 2021 was a sign of the beginning of Delta variant, which reached the peak of hospitalization (almost 1 month and 10 days) on August 10, 2021.
Figure 2.
The trend of hospital admission in Guilan province during the study period.
Figure 3 presents the effectiveness of covid-19 vaccines on disease outcomes (temporary admission, regular admission, ICU admission and death) by the interval between the first, second, and third doses.
Figure 3.
The effectiveness of Covid-19 vaccines on disease outcomes (temporary admission, regular admission, ICU admission and death) by the interval between the first, second, and third doses.
The highest effectiveness of the vaccine was observed in the temporary admission, ICU admission, and death about 6 months after the second dose in Sinopharm (BBIBP-CorV) and Sputnik V (Gam-COVID-Vac) vaccines (We did not include Bharat vaccine in subgroups because of small sample size). The highest effectiveness of the vaccine in the regular admission was observed about 6 months after the second dose in Sinopharm (BBIBP-CorV) and AstraZeneca (ChAdOx1-S-(AZD1222) vaccines.
A significant statistical relationship was seen in the relationship between the control group and the case with the variables (age group, gender, healthcare workers, vaccination status, and hospital section [P <0.05] except the history of PCR positive).
Tables 2 and 3 show the effectiveness of the Covid-19 vaccine on disease outcomes with the first, second and third doses, as shown in the table, the effectiveness of covid-19 vaccines increases over time. The reason for the low effectiveness of vaccines in the ICU department and death compared to temporary and regular hospitalization is because of low availability of vaccines, reduced effectiveness of vaccines in various mutations, noncompliance with health protocol after vaccine injection, etc.
Table 4 show describing the five vaccine studies.
Table 4.
Describing the five vaccines studies.
| Vaccine name | Number of doses (dosage) | Interval between doses | Age indication | The number of first doses taken during the study | The number of Second doses taken during the study | Technical platform |
|---|---|---|---|---|---|---|
| BBIBP-CorV | 2 doses (0.5 ml each) | 4 weeks | 18 years and older | 1643361 | 1576347 | Inactivated virus |
| ChAdOx1-S-(AZD1222) | 2 doses (0.5 ml each) | 4-12 weeks | 18 years and older. | 234501 | 197464 | Viral vector (Non-replicating) |
| Gam-COVID-Vac (Sputnik V) | 2 doses (0.5 ml each) | 3 weeks | 18 years and older. | 10054 | 11886 | Viral vector (Non-replicating) |
| ChAd36-SARS-CoV | 2 doses (0.5 ml each) | 4 weeks | 18 years and older | 1713 | 1662 | Viral vector (Non-replicating) |
| BIV1-CovIran | 2 doses (0.5 ml each) | 4 weeks | 18 years and older | 119070 | 111591 | Inactivated virus |
Discussion
In the study of the effectiveness of vaccines used in Guilan Province, we concluded that the effectiveness of Sputnik V, AstraZeneca, and Sinopharm vaccines in patients admitted to the regular ward in the period of 21 days after first dose receiving the vaccine reached 80% and 73% and 22% respectively. Also, the effectiveness of Sinopham and AstraZeneca vaccines in preventing death in the period of 21 days after the first dose receiving was showed 17% and 37% respectively. COVIran Barekat 61-90 days after the second dose, had >95% effectiveness in preventing temporary and regular hospital admission compared to unvaccinated people, but its maximum effectiveness against death 61-90 days after the second dose, had >88%. The effectiveness of Sputnik V vaccine in preventing temporary hospital admission and regular ward was estimated to be >93% compared to unvaccinated individuals ≥151 days after receiving the second dose. Sinopharm showed an effectiveness of >94% in preventing temporary hospital admission and regular admission ≥151 days after the second dose vs unvaccinated individuals, but its maximum effectiveness against ICU 61-90 days after the second dose, had >55%. The effectiveness of two doses Sinopharm vaccine against death compared to nonvaccinated individuals was estimated 56%, 91-120 days after the second dose. The effectiveness of AstraZeneca in preventing death was estimated at 92%, 121-150 days after receiving the second dose. The effectiveness of Bharat in preventing regular ward 151 days after receiving the second dose was estimated at 57%.
For almost all vaccines, the study observed an increase in effectiveness against hospitalization and death over time. The effectiveness of Sputnik V, AstraZeneca, and Sinopharm vaccines against regular hospitalization seems to remain at an optimal level for at least 6 months after receiving the second dose. The effectiveness of Sputnik V and Sinopharm vaccines against temporary hospitalization seems to remain at the optimal level for at least 6 months after receiving the second dose. The effectiveness of COVIran Barekat in preventing regular hospitalization and death seems to remain at an optimal level, 4 months after receiving the second dose. The effectiveness of AstraZeneca vaccine in preventing death remains at optimal level, 5 months after receiving the second dose.
A study conducted in the United Arab Emirates on the effectiveness of Sinopharm in the prevention of COVID-19 admission and death concluded that a single dose of Sinopharm did not have any significant effectiveness in this regard. The effectiveness of the vaccine in people who had received two doses compared to nonvaccinated individuals in the prevention of hospital admission, ICU admission, and death was 80%, 90%, and 97%, respectively, while in the current study, this vaccine was less effective in preventing admission and death [24]. Another study conducted in France on the effectiveness of the vaccines used in that country (Pfizer, AstraZeneca, etc.) against hospital admission reported results that were similar to our findings. In their study, the effectiveness of AstraZeneca reached over 90% after two doses [25]. Another study in Canada on the effectiveness of the vaccines used in that country (Pfizer, AstraZeneca, etc.) against symptomatic infection and severe disease consequences (hospitalization and death) showed high effectiveness (91%) after the first dose of AstraZeneca against Delta variant in contrast to our study, again they also reported >90% effectiveness after the second dose of this vaccine against Delta variant, which was similar to our study findings [26]. In a study conducted in Shiraz (Iran) on the effectiveness of the vaccines used in preventing infection, hospitalization, and death, results similar to our findings were obtained. The effectiveness of two doses of Sinopharm, AstraZeneca, Sputnik V, and COVIran Barekat in reducing hospital admission was respectively 71.9%, 81.5%, 67.5%, and 86.4%; also in our study, a very similar effectiveness was reported for all these vaccines [27]. Another study on the effectiveness of Pfizer and AstraZeneca in the United Kingdom for the Delta and alpha variants showed that the effectiveness of two doses of AstraZeneca against the Delta and alpha variants was 67% and 74%, respectively. In general, similar to our finding, they observed a slight difference in effectiveness after receiving two doses against the Delta variant compared to the alpha variant [16]. The limitations of the present study include the lack of access to participants’ underlying disease history in the control group, which is an important factor in vaccine effectiveness. Moreover, data was not available on the outpatients with negative RT-PCR tests in private-sector laboratories, because the private sector only reports positive cases. The strengths of this study include the simultaneous evaluation of four disease outcomes, assessing vaccines approved by the MoHME, and reporting results for different time intervals after the vaccine doses.
Conclusion
The effectiveness of Sinopharm vaccine in preventing temporary and regular hospitalization 1-30 days after receiving the second dose reached at least 60%, but after 5 months, the maximum effectiveness was showed between 85-95%. The maximum effectiveness of Sinopharm vaccine in preventing death after receiving the second dose was showed 56% after 4 months. The minimum effectiveness of AstraZeneca vaccine in preventing temporary and regular hospitalization 21 days after receiving the first dose was observed at least 50%, but 4 months after the second dose, effectiveness was shown over 90%. The maximum effectiveness of AstraZeneca vaccine in preventing death was shown over 90%, 5 months after the second dose. The maximum effectiveness of COVIran Barekat vaccine in preventing temporary and regular hospitalization 3 months after the second dose was reached over 90%, but the maximum effectiveness of COVIran Barekat vaccine in preventing ICU admission 3 months after the second dose was reached 70%. The maximum effectiveness of COVIran Barekat vaccine in preventing death 4 months after the second dose was reached over 90%. The maximum effectiveness of Sputnik V vaccine in preventing temporary, regular hospitalization and death 6 months after the second dose was reached over 90%. The maximum effectiveness of Bharat vaccine in preventing regular hospitalization 6 months after the second dose was reached over 90%. Future studies can be investigated in relation to the combined effectiveness of vaccines.
Declaration of competing interest
The authors have no competing interests to declare.
Funding
This Study was supported by the Deputy of Health, Guilan University of Medical Sciences (Grant NO. 4230).
Ethical approval
All the principles and standards of the Iranian National Ethics Committee have been observed. This project has been approved by the Ethics Committee of Guilan University of Medical Sciences (IR.GUMS.REC.1401.178).
Author contributions
AH: conceptualization, methodology, validation, analysis, research, examination, drafting the manuscript, editing, and finalization, visualization, supervision, project management; MAM: methodology, validation, analysis, research, examination; SKH: methodology, validation, analysis, research, examination, drafting the manuscript, editing, and finalization; SK: methodology, validation, analysis, research, examination, drafting the manuscript, editing, and finalization; MH: data collection; MK: drafting the manuscript, editing, and finalization.
Footnotes
Guide to diagnosis and treatment of covid-19 disease in providing outpatient and inpatient services (MoHME).
Guide to diagnosis and treatment of covid-19 disease in providing outpatient and inpatient services (MoHME).
Guide to diagnosis and treatment of covid-19 disease in providing outpatient and inpatient services (MoHME).
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