ABSTRACT
Background and Objectives:
There is more possibility of COVID-19 among obese people; hence, research into how well vaccinations work in this population should be focused. More scientific studies are required to document the effect of body mass index (BMI) on the usefulness of the adenovirus vector vaccine as reviews are lacking. This study was done to see the association between obesity with COVID-19 infections due to poor vaccine response among them.
Methods:
A cohort of fully vaccinated individuals of a city in western India were contacted, and a retrospective cohort study was conducted. An average of 400–425 participants among the obese group (exposed) and an average of 400–425 participants among the nonobese group were taken. Data on sociodemographic details, vaccination status, height and weight for BMI calculation, COVID-19 infection status, and its clinical features were collected using predesign, pretested, semistructured questionnaires. Societies were randomly selected from eight different zones of the city, and all the eligible individuals of the society available at the time of survey were interviewed. Data entry and analysis were done using Microsoft excel, Open Epi, Quantpsy, and SPSS-16 software. Relative risk and odds ratios were calculated in open epi software.
Results:
The ratio of obese to nonobese individuals was 1:1. Accordingly, 409 obese and 409 nonobese participants were recruited. The mean age of participants was 41.3 ± 14.9 years. As high as 144 (17.6%) of respondents were having history of previous infection before vaccination, and around 42 (5.1%) respondents of the overall study population were infected after the first dose of vaccination. The total count of people for infections before receiving a single dose of vaccination irrespective of body status was reported to be 144 (17.6%) out of a total of 818 candidates.
Interpretation and Conclusions:
We can conclude that not only obesity is a risk factor but also it increases the severity of COVID-19 infection.
Keywords: COVID-19, infections, obesity, risk factor, vaccination
Introduction
Scientists have postulated that the current available vaccines will offer decreased immunity in obese individuals, pointing onto the corroboration of imperfect regulation of the immune system and changes in inflammatory signaling pathways.[1]
The correlation of obesity with COVID-19 is not clear and has scarce systematic reviews.
A meta-analysis of approximately 75 studies is available in the literature to document the relation of individuals with obesity and susceptibility to COVID-19-induced deaths. Results document that obese people are more susceptible for infection, >46.0%.[1]
Excess body fat severely affects the body’s immunity, and this leads to an increased concern for the lack of vaccine-induced resistance to infections in obese patients and thus needs a review about the better protection of this subpopulation.[2]
The body’s immunity is severely affected by excess body fat; therefore, obese patients lack vaccine-induced resistance to infections, so this subpopulation needs search for their protection.
The AZD1222-ChAdOx 1-S (Covishield) vaccine, produced in India by the Serum Institute of India under the license from Astra Zeneca-Oxford,[3] and the indigenous vaccine BBV15 (Covaxin), created by Bharat Biotech in collaboration with the Indian Council of Medical Research (ICMR),[4] were among the vaccines that the regulatory authority approved and deployed in India. The severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) spike protein gene is expressed in the AZD122 (ChAdOx 1-S/nCoV-19) recombinant vaccine against COVID, a replication-deficient adeno-viral vector vaccine.[3] A whole-virion COVID vaccine called BBV152 is adjuvanted with Algel-IMDG to stimulate T helper-1 cell (Th1) responses.[4] The effectiveness of AZD1222 (ChAdOx 1-S) following administration of two doses of the vaccinations has been reported as 63.1% and perhaps better efficiency on longer intervals. According to preliminary data from a phase 3 clinical trial, BBV152 had a 78% success rate in preventing COVID infection.[4]
Due to more chances of COVID-19 among obese people, research on protection from vaccinations should be focused in this group of people. As little review is available on the effect of body mass index (BMI) on the efficacy of the adenovirus vector vaccine, more scientific work needs to be done.
Our study was planned to analyze the data which connect obesity to poor vaccine immune responses, leading to higher COVID-19 breakthrough infections, which is poorly described and requires further explanation.
Aims and objectives
To recognize and document obesity as a risk factor for COVID-19 infections.
To document prevalence of COVID-19 infections among fully vaccinated obese and nonobese individuals.
To document severity of COVID-19 infections among fully vaccinated obese and nonobese individuals.
To document obesity as a risk factor among fully vaccinated individuals for breakthrough infection of SARS-CoV-2.
Materials and Methods
A retrospective cohort study was carried out among a cohort of fully vaccinated individuals of a city in western India. The city had achieved a total vaccination coverage of 91% of the second dose (on the first dose) in individuals with an age above 18 years. A total of 802,123 precautionary doses of the vaccine were administered to the population (As on September 2021).
Standardized definitions used in the study
Breakthrough infection: Persons tested positive for COVID-19 infection via RT-PCR/rapid antigen detection after being fully vaccinated for COVID-19.[5]
Fully Vaccinated: A person who has received both their doses of primary series of COVID-19 vaccines.[6]
Body Mass Index (BMI) = Weight (Kilograms)/(Height) 2 (Meters)
Exposed Group – Obese: BMI = 30 (42)
Unexposed Group – Nonobese: BMI <30 (42)
Study design: Retrospective cohort study
Study setting: Eight zones of Surat city.
Study duration: Two months, 1 month for data collection and 1 month for analysis plus report writing.
Study population: Fully vaccinated individuals of all eight zones of a city as per belowmentioned inclusion and exclusion criteria.
Inclusion criteria
Age 18 years and above.
Willing to participate and give consent for this study.
Exclusion criteria
Individuals suffering from any comorbidity other than obesity.
Individuals suffering from any comorbidity other than obesity.
All pregnant females.
Partially vaccinated, who has received only one dose of COVID-19 vaccines.
Sample Size: An average sample size of 800–850. An average of 400–425 participants among the obese group (exposed) and an average of 400–425 participants among the nonobese group (unexposed) were taken.
Sample Size Calculation: The minimum total sample size was calculated to be about 794, which included a minimum of 397 obese and a minimum of 397 nonobese participants at a power of 80%, and the ratio of exposed, obese, and unexposed, nonobese, is taken 1.
The total sample size was calculated based on a previous study conducted by de Lusignan et al.[7] According to this study, the odds ratio for obesity and COVID-19 infection is 1.74.[7] Sample size calculation was done in Open Epi software Version 3.
Sampling Technique: Purposive sampling technique
Recruitment process: A society or societies were selected randomly from eight different zones of the city [Figure 1], and all the eligible individuals of the society available at the time of survey were interviewed for the study. The study was continued till the desired sample size was achieved from each zone.
Figure 1.
Zonewise distribution of areas in the studied city
Study tool: To collect data on sociodemographic details, vaccination status, height and weight for BMI calculation, COVID-19 infection status, and its clinical features, a predesigned, pretested, semistructured questionnaire was used. It was translated and validated in Hindi and Gujarati for the local participants for their understanding during data collection. Measurement for weight and heights was taken accordingly as mentioned below.
(1) Weight:
Subjects were asked to stand barefoot on a weighing machine. Weight was calculated on a standardized weighing machine to nearest kilograms.
(2) Height:
It was calculated by instructing the eligible voluntary participant to stand erect and bare foot keeping his/her heels together on a flat surface. The heels, buttocks, and back must be pressed against the wall with the head positioned in the Frankfort horizontal plane and the arms hanging freely to the sides. A flat measuring scale was kept at the superior most part of the head, pressing firm enough to compress the hair.
Methods such as waist-to-hip ratio and other ones were excluded due to chances of nonacceptance by female respondents.
Variables: The variables used in the study were sociodemographic, vaccination status, height and weight for BMI calculation, and other details of COVID-19.
Primary outcome: COVID-19 breakthrough infections among fully vaccinated obese and nonobese groups with COVID-19 breakthrough infections and obesity as the risk factor for the same.
Secondary outcome: Sociodemographic profile of study participants.
Statistical analysis: Data were entered in Microsoft excel software and analyzed using Microsoft excel, Open Epi (version 3.01), Quantpsy, and Statistical Package for the Social Services (SPSS)-16. Data are represented as mean and proportions. Relative risk and odds ratios were calculated in open epi software. Chi-square was applied as test of significance. When the expected value was less than 5, Yates’ correction was applied. A P value of < 0.05 was considered significant at 95% significance level.
Ethical considerations and confidentiality
Approval was obtained from Institutional Ethics Committee with approval no. of GMCS/STU/ETHICS-2/Approval/21332/22 20081/22 date: 12/08/2022. Unique ID was given to participants to maintain confidentiality, and those who were willing to participate and give consent were only recruited. Those with complication of obesity and COVID-19 were referred to a tertiary care hospital.
Quality Control: For feasibility and making any changes in the study, pilot testing of data starting from study procedures for recruitment till data entry was done. The questionnaire was administered by the investigator himself to maintain quality of data collection.
Results
The study population comprised a total of 818 participants of eight different zones of the city. The ratio of obese to nonobese individuals was 1:1. Accordingly, 409 obese and 409 nonobese participants were recruited. The mean age of participants was 41.3 ± 14.9 years.
Males and females were equally distributed with 409 males and 409 females. Approximately one out of three respondents was a home maker, while approximately one fifth of respondents were doing business, followed by job and students. The majority 230 (28.4%) of the individuals of our study population belonged to age category of 41–50 years, followed by the age range of 18–30 years 215 (26.5%). There was an equal distribution of obese and nonobese individuals as mentioned in our study methodology [Table 1].
Table 1.
Sociodemographic profile of study participants
| Variable | Number | Percentage (n=818) |
|---|---|---|
| Gender | ||
| Male | 409 | 50.0 |
| Female | 409 | 50.0 |
| Age | ||
| 18-30 | 215 | 26.5 |
| 31-40 | 178 | 22.0 |
| 41-50 | 230 | 28.4 |
| 51-60 | 96 | 11.8 |
| 61-70 | 77 | 9.5 |
| 71 and above | 22 | 2.7 |
| Occupation | ||
| Homemaker | 313 | 38.3 |
| Business | 176 | 21.5 |
| Students | 130 | 15.9 |
| Job | 122 | 14.9 |
| Others | 77 | 9.4 |
| Body Status | ||
| Obese | 409 | 50.0 |
| Nonobese | 409 | 50.0 |
Table 2 depicts the information regarding COVID exposure, vaccination status, and breakthrough infection post vaccination. 58 (7.1%) individuals had a prior history of traveling during COVID. As Covishield vaccine was rampantly available through the government system, it was natural that approximately 96% individuals received Covishield vaccines as their primary mode of vaccination. Approximately one-third individuals received their precautionary dose as recommended by the government. As high as 144 (17.6%) of respondents were having history of previous infection before vaccination, and around 42 (5.1%) respondents of the overall study population were infected after the first dose of vaccination. A total of 20 (2.4%) COVID-19 breakthrough cases was reported among the study population. A total of (38.9%) individuals reported to have a prior history of contact with count to as high as 319.
Table 2.
COVID-19 details of the study participants
| Variable | Number | Percentage (n=818) |
|---|---|---|
| History of Travel During Covid | ||
| Yes | 58 | 7.1 |
| No | 760 | 92.9 |
| Vaccination Details | ||
| Covishield | 793 | 96.8 |
| Covaxin | 23 | 2.8 |
| Others | 3 | 0.4 |
| Dose | ||
| 1st, 2nd | 528 | 64.5 |
| 1st, 2nd, Booster | 290 | 35.5 |
| History of Covid before vaccination | ||
| Yes | 144 | 17.6 |
| No | 674 | 82.4 |
| History of Covid After 1stDose | ||
| Yes | 42 | 5.1 |
| No | 776 | 94.9 |
| History of Covid After 2nd Dose | ||
| Yes | 20 | 2.4 |
| No | 798 | 97.6 |
| History of contact | ||
| Yes | 319 | 38.9 |
| No | 499 | 61.1 |
Table 3 depicts obese and nonobese participants after the respective doses of vaccines and SARS-CoV-2 infections. The rate of COVID-19 positivity among the obese participants before vaccination was around 20%, whereas among nonobese individuals, the positivity rate for the same stood at about 15.1%. The obese participants were found to be at a slightly higher risk than nonobese for infections after the first dose of vaccination. However, the difference is statistically insignificant.
Table 3.
History of COVID-19 infection in the obese and nonobese participants before and after the vaccination (Obese=409, Nonobese=409)
| Vaccination Status | Body Status | H/O COVID-19 Infection | RR (CI) | OR (CI) | P | |
|---|---|---|---|---|---|---|
|
| ||||||
| Yes (%) | No (%) | |||||
| Before Vaccination | Obese | 82 (20) | 327 (80) | 1.32 (0.98-1.79) | 1.40 (0.97-2.01) | 0.6 |
| Nonobese | 62 (15.1) | 347 (84.9) | ||||
| After 1st dose | Obese | 24 (5.8) | 385 (94.1) | 1.33 (0.73-2.42) | 1.35 (0.72-2.54) | 0.34 |
| Nonobese | 18 (4.4) | 391 (95.5) | ||||
| After 2nd dose | Obese | 16 (3.9) | 393 (96.0) | 4 (1.3511.86) | 4.12 (1.3712.44) | <0.01 |
| Nonobese | 04 | 405 | ||||
OR - Odds ratio, RR - Relative Risk, CI - Confidence Interval
A total of 82 (20%) out of 409 obese individuals reported to have had a positive COVID infection before they received their COVID vaccination; similarly, the count of a positive COVID infection before the vaccination for a total of 409 nonobese individuals stood at 62 (15.1%). The total count of people for infections before receiving a single dose of vaccination irrespective of body status was reported to be 144 (17.6%) out of a total of 818 candidates (RR–1.3295% CI: 0.98-1.79, OR–1.4095% CI: 0.97-2.01) (P = 0.6).
Out of all the obese individuals, 24 (5.8%) gave history of a positive COVID-19 infection after receiving their first dose of vaccination for COVID-19, and the positivity count for the same was 18 (4.4%) in nonobese participants.
The overall enumeration irrespective of body status for infections after the first dose of vaccination was a total of 42 (5.1%) out of all study participants (RR-1.33, 95% CI: 0.73-2.42, OR-1.3595% CI: 0.72-2.54) (P = 0.34).
3.9% of overall obese participants had a positive breakthrough infection even after having a complete immunization with both doses of vaccine. Among 409 nonobese individuals who have received both doses of vaccine, the count rate of a positive COVID infection was 4 (0.98%). The overall count of identified breakthrough cases irrespective of any other confounding factors in the study population was 20 (2.4%) out of the total study population (RR-4, 95% CI1.35-11.86, OR-4.12, 95% CI1.37-12.44, P < 0.01).
As previously interpreted by the represented data (in Table 3), a total of 144 individuals had a history of being positive for COVID infection before receiving their first dose of vaccination. The mean BMI of these 144 participants was 29.1 ± 4.22 and the mean BMI of the rest of the study participants who were not infected with COVID-19 before vaccination was 28.1 ± 5.15 (P < 0.05), and these results obtained were significant statistically. The mean BMI of the individuals having a positive history of infection after getting their first dose of vaccination was 28.88 ± 3.89. The rest 776 participants belonging to the study population who were not infected had their mean BMI as 28.22 ± 5.06. (P = 0.29). 20 (3.9%) of the overall population were accounted for having breakthrough infection; the mean BMI of these participants was calculated to be 30.35 ± 4.36 and the remaining 798 (97.55%) people from the study population who were safe from breakthrough infections had their average BMI equal to 28.22 ± 5.01; results are statistically significant with (P < 0.05) [Table 4].
Table 4.
The mean BMI of study participants in positive and negative history of COVID-19 infections before and after vaccination
| Vaccination status | History of COVID-19 infection | Body Mass Index (BMI) | ||
|---|---|---|---|---|
|
| ||||
| Mean | SD | P | ||
| Before vaccination | Yes | 29.1 | 4.22 | <0.05 |
| No | 28.1 | 5.15 | ||
| After 1st dose | Yes | 28.88 | 3.89 | 0.29 |
| No | 28.22 | 5.06 | ||
| After 2nd dose | Yes | 30.35 | 4.36 | <0.05 |
| No | 28.22 | 5.01 | ||
SD - Standard Deviation
As represented in Figure 2, the most common symptom in participants before vaccination was fever (110), after the first dose (20) and after the second dose (16). Cough was the second most prevalent symptom in the participants, and the overall figures were 84, 21, and 13 before vaccination, after the first dose and second dose, respectively. Seven (7) were reported to be asymptomatic during infection before vaccination, whereas the count for asymptomatic, after the first and second dose, was 1 and 2, respectively.
Figure 2.
Distribution of various symptoms in individuals with a positive history of COVID-19
Before vaccination, a total of 13 individuals out of those totally infected required oxygen support, and among them, 61% were obese and 31% were nonobese. Four required O2 support when they were infected after receiving their first dose of vaccination and all of them were obese according to their body status, whereas after the second dose of vaccination, six of the totally infected participants required O2 support, and out of them, five were obese [Figure 3].
Figure 3.
Oxygen support requirement in individuals tested positive for COVID-19 infection before and after vaccination
A total of 19 individuals who had a history of SARS-CoV-2 infection before vaccination were admitted to the hospital, and the count of hospital admission for obese and nonobese was 10 and 9, respectively. The hospitalization rate was dropped to a count of 4 in individuals affected after receiving their first dose of vaccination; all the hospitalized individuals were obese. Seven respondents gave a history of hospitalization due to COVID-19 breakthrough infection after receiving their second dose of vaccination. All the seven respondents were obese [Figure 4].
Figure 4.
Distribution of hospitalization and home isolation among the individuals who were affected with COVID-19 before and after vaccination
Discussion
This study was planned to identify obesity as a possible risk factor for COVID-19 breakthrough infection. 96.8% study participants had taken Covidshield as their primary mode of vaccination, 2.8% participants had taken Covaxin vaccine, and 0.4% were classified into the category of others. There was an equal distribution of males and females. The study conducted by Piernas et al.[8] comprises 47% males and 53% females.
In this study, 21.5% were doing business, 38.3% were housewives, and 15.9% were students. Basso et al.[9] conducted a study on breakthrough infection among healthcare workers including 10.4% physicians, 37.5% nurses, 23.6% nurse aids, 22.11% technicians, and 10.2% administrative staff.
The average age of participants was 41 years, while a study conducted by Muscogiuiri et al.[10] identified the average year of participants as 42 years among those who had received the first dose of vaccine, 40 years among those who had received the second dose of vaccine, and 46 years among those who had received the third dose of vaccine.
7.1% of participants had a prior history of traveling during COVID. 92.9% did not have any traveling history. 35.5% of participants received their precautionary dose. In a population-based cohort study by Piernas et al.[8] carried out in England, 25% of participants had received three doses of vaccines.
This study recognizes that obese participants had 1.32 times greater risk of developing a COVID-19 infection before vaccination compared to the nonobese participants. After taking the first dose of vaccination, risk is almost similar; obese individuals had 1.33 times the risk of COVID-19 infection compared to nonobese individuals. But after receiving the second dose of vaccination, obese participants had four times the risk of developing COVID-19 infection compared to nonobese participants. Basso et al.[9] stated that odds of having BMI >25 are 1.5 times higher in COVID-19 breakthrough infection in comparison to participants with no COVID-19 breakthrough infection. Faizo et al.[11] suggested that COVID-19 vaccines are highly effective, but its efficacy is potentially reduced in obese individuals.
In this study, those who had COVID-19 infection in the past before vaccination had a higher BMI compared to the individuals who had a negative history of past COVID-19 infections. After receiving the second dose of vaccination, those who were COVID-19-positive had their BMI higher by 2 points than those who reported themselves as COVID-19-negative after receiving both doses of vaccination. Basso et al.[9] had BMI >25 among 50.4% participants with breakthrough infection. Muscogiuri et al.[10] conducted a study on COVID-19 breakthrough infection, in which after the first dose, the average BMI was 31.4 Kg/m2 among participants and 36.8 Kg/m2 after the second dose of vaccination and it was the highest, and after the third dose, it was 34 Kg/m2. Another study conducted by Pellini et al.[12] reports low-serum antibody titers in persons with higher BMI, which points toward higher risk of breakthrough infections among obese individuals.
The most common symptom was fever before vaccination (110) after the first dose (30) and after the second dose,[13] followed by cough 82, 21, and 13 before and after the respective vaccination doses. Before vaccination, seven were asymptomatic; after the first and second doses, 1 and 2 were asymptomatic, respectively.
Among COVID-19-positive individuals, a total of 19 were admitted to the hospital before vaccination; among them, ten were obese and nine were nonobese. After the first dose of COVID-19 vaccination, four were admitted to the hospital and all four were obese. After the second dose, seven were admitted to the hospital and all seven were obese. Observations from a prospective, community-based cohort study comprising 6,910,695 SARS-CoV-2-infected patients from 1500 general practices in England revealed nonlinear associations between BMI above 23 kg/m2 and higher risk of hospitalization [adjusted HR (hazard ratio) per kg/m2 in comparison to risk among individuals with BMI of 23 kg/m2 -1.05, 95% CI 1.05–1.05] and death. It was also demonstrated that there is a direct association between BMI and ICU admission (HR - 1.1, 95% CI: 1.09-1.1).[14] A meta-analysis conducted by Yi Huang et al.[15] also concluded that among patients with COVID-19, obesity intensifies the probability of hospitalization, ICU admission, requirement for ventilation, and mortality.
Before vaccination, total 13 require O2 support; among them, eight were obese and five were nonobese. After the first dose, four required O2 support and all four were obese. After the second dose of vaccination, six required O2 support; among them, five were obese and one was nonobese. A study conducted by Muscogiuri et al.[10] identifies four participants with hospitalization; among them, one who had received the second dose of vaccination required intensive hospitalization. Another study conducted by Nakeshbandi et al.[16] recognized obese patients have 2.4 times higher chance to be intubated than nonobese participants. Another article by Frank et al.[17] stated that the possibility of intubation or mortality was raised 2.3 times (95% CI, 1.2–4.3) when BMI was more than or equivalent to 30 kg/m2.
The study has a sizable sample size and is sufficient and likely the first research of its sort to come from India. The load of breakthrough infections can be estimated in the vaccines currently being rolled out in India.
The study concludes obesity as a risk factor for COVID-19 breakthrough infection; moreover, it increases the severity of infection. Among obese participants, the proportion of hospitalization and oxygen support requirements was more at the time of COVID-19 breakthrough infection in comparison among nonobese participants. Similar findings were also observed in COVID-19 infections before vaccination. The study population affected from COVID-19 breakthrough infection was found to have a higher mean BMI than others who did not have a breakthrough infection.
Our research addresses obesity as one of the risk factors for breakthrough infection of COVID-19 despite being fully vaccinated and the need of their priority vaccination over the general fit population. The study also highlights the fact that with obese participants being at a higher risk, there is a need to increase their awareness level and priority for precautionary dose vaccination. This will ultimately result in reducing the burden on the health care system. Young researchers have also successfully learned the process of research methodology and its application during the conduction of study.
The study was conducted over one of the largest cities of western India, and samples were collected from all eight zones of the city which are geographically diverse and contain the heterogeneous population. So, results of this study will be applicable to the entire western Indian population. Moreover, limited information is available on this particular subject; more futuristic studies are also recommended.
Ethical clearance
Approval was obtained from Institutional Ethics Committee with approval no. of GMCS/STU/ETHICS-2/Approval/21332/22 20081/22 date: 12/08/2022.
Conflicts of interest
There are no conflicts of interest.
Acknowledgement
Our acknowledge to ICMR-STS for approving this research under ICMR-STS (Reference ID: 2022-11495) programme and giving us the opportunity to carry out research. We are thankful to institute for permitting us to conduct research at field level. We are thankful to all the participants for their co-operation and giving their valuable time for data collection. We acknowledge support received from our colleagues during data collection.
Funding Statement
Nil.
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