Table 2.
List of studies on the purified inactivated SARS-CoV-2 vaccine Covaxin.
| Study | Type of study | Number of participants | Study groups involved | Findings on immunogenicity/efficacy | Findings on safety | Additional comments | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mohandas et al. (23) | Non-human study | 36 Syrian hamsters with 9 in each group | Group I -phosphate-buffered saline (PBS) | IgG negative till virus challenge IgG +ve in all by 14 DPI (OD=0.29) No NAb (PRNT50) response till 15 DPI Throat swab Viral gRNA copy number highest post challenge and persisted till 10 DPI |
Not mentioned in study | 3 Doses(Day 0,14,35) given. Vaccinated hamsters had lower weight loss following virus challenge. All vaccinated groups induced IgG2 and the NAb appeared at 3 weeks peaking at 7 weeks All vaccinated groups had normal morphology compared to congestive, fibrotic and haemorrhagic features in group I. No significant elevation of cytokines in vaccinated compared to IL-12 elevation in controls. |
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| Group II (BBV152C)- 6µg vaccine + Algel | IgG Ab in 3rd week in 2 of 9 (OD=0.285) IgG Ab on day 48 in 9 of 9 (OD=0.55) Throat swab & trachea viral clearance on 7 DPI Lungs viral clearance on day 15 DPI |
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| Group III (BBV152A)- 3µg vaccine + Algel-IMDG) | IgG Ab in 3rd week in 8 of 9 (OD=0.42) IgG Ab on day 48 in 9 of 9 (OD=1.2) Highest observed NAb(PRNT50) (mean=28,810 at 7th week) and post challenge mean=85,623) on 15 DPI Throat swab, lungs & trachea viral clearance on 7 DPI |
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| Group IV (BBV152B)- 6µg vaccine + Algel-IMDG | IgG Ab in 3rd week in 8 of 9 (OD=0.62) IgG Ab on day 48 in 9 of 9 (OD=1.32) Throat swab, lungs & trachea viral clearance on 7 DPI |
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| Yadav et al. (8) | Non-human primate study | 20 Rhesus Macaques with 5 in each group | Covaxin 6μg+ Alum | IgG titer 1:1600-1:6400 NAb titer 1:87.4 - 1: 3974 Throat swab -viral clearance on 7 DPI BAL fluid viral clearance on 5 DPI |
No Adverse events noted | 2 dose (day 0,14) study. Necropsy Lung specimens negative for gRNA and sgRNA in vaccinated groups. Radiographic abnormalities resolved by 5 DPI in 2 vaccinated groups other than the 3µg + alum +imidazoquinoline group which showed No clinical or radiographic abnormalities. Resistance to pneumonia on Histopathological examination unlike placebo. Pro-inflammatory cytokines such as IL-6 were lower and anti-inflammatory cytokines such as IL-5 higher in all vaccinated. |
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| Covaxin 3μg + alum+ imidazoquinoline | Highest IgG titer (1:25600) Highest NAb titers of 1:209 to 1:5,217 Throat swab viral clearance on 7 DPI BAL fluid viral clearance on 5 DPI |
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| Covaxin 6μg+ alum+ imidazoquinoline | IgG titer 1:1600-1:6400 NAb titer 1: 29.5 -1: 3403 Throat swab viral clearance on 7 DPI BAL fluid viral clearance on 5 DPI |
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| Placebo | No NAb and IgG response Throat swab viral clearance not seen even by 7 DPI BAL fluid viral clearance not seen even by 7 DPI |
Chest X-ray showed infiltrates, bronchopneumonia, or lobar pneumonia which persisted till 7 DPI. | |||||||||||||||||
| Ganneru et al. (7) | Pre-clinical study on 3 animal species | BALB/c mice at 1/20th or 1/10th Human single dose + adjuvant (intra-peritoneally) | High Ag Binding and NAb titers(PRNT90) (100% seroconversion) Day 7 -102 titer Day 14 – 103 titer Day 21 – 104 titer Day 28 – peak titer Adjuvanted (algel/algel-IMDG) formulations elicited high Ab levels targeted against S1 compared to non-adjuvanted and lasted 98 days. |
Only local reactogenicity observed which was self resolving | Algel-IMDG found non-mutagenic and well tolerated at test as well as repeat dose in the 3 animal models. The TLR7/8 agonist adjuvant supports Th1-biased Ab responses and has high IgG2a/IgG1 ratio, IFN-γ response compared to algel. |
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| New Zealand White rabbits | High NAb titers (PRNT90 as well as MNT50) comparable to convalescent human sera Day 21- 104 titer (100% seroconversion) |
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| Wistar rats & Swiss Albino mice | Maximum Tolerated dose (=Human single dose) and repeated dose elicited no ill-effects | ||||||||||||||||||
| Zare et al. (10) | Cross-sectional study on health workers | 503 Health care workers given atleast 1 of 3 different vaccine | Covaxin (42) | None performed | 92.9 % had side effects. Injection site pain (83.7%) >Fatigue (41.9%) >headache (27.9%) | Injection site pain was most common in all three vaccines. AZD1222 had highest %age of systemic side-effects. Prevalence rate of complications in Covaxin not significantly different from Sputnik-V and AZD1222. No serious/life-threatening side effects observed in all 3 vaccine groups. Side-effects disappeared by 7 days post-innoculation in all groups. |
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| Sputnik-V(238) | 81.9 % had side-effects. Injection site pain (56.7%) >Muscle pain (41.6%) >Fever & chills (37.4%) |
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| AZD1222 (223) | 88.8 % had side-effects. Injection site pain (70%) >Fatigue (68.4%) >fever & chills (67.1%) |
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| Singh et al. (COVAT study) (26) | Cross-sectional study of Health care workers | 96 (1st dose) 90 (2nd dose) | Covaxin | Seropositivity after 1st dose- 43.8% GMT’s after 1st dose- 16.8 AU/mL. Seropositivity after 2nd dose- 80% GMT’s after 2nd dose- 48.3 AU/mL. |
31.2% mild-moderate side-effects after 1st dose and 11.1% after 2nd dose. Breakthrough infections in 2.2%. No serious AEFI |
People with comorbidity especially Type 2 Diabetes had lower seropositivity in both vaccines. Past history of infection resulted in overall significantly higher seropositivity vis-à-vis unexposed individuals. Females also had 9% higher seropositivity. Covishield had significantly increased seropositivity, NAb titer after 1st dose while Covaxin required 2 doses to achieve significant effect. |
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| 456 (1st dose) 425 (2nd dose) | Covishield | Seropositivity after 1st dose- 86.8% GMT’s after 1st dose- 62.4 AU/mL. Seropositivity after 2nd dose- 98.1% GMT’s after 2nd dose- 129.3 AU/mL. |
Higher mild-moderate side-effects 46.7% after 1st dose and 18.1% after 2nd dose. Breakthrough infections in 5.5%. No serious AEFI. |
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| Singh et al. (COVAT study follow-up) (30) | 6-month longitudinal study | 74 | Covaxin | Anti- spike GMT (AU/ml) (SARS-CoV-2 naïve cohorts) 21 days post 1st dose- 16.17 21 days post 2nd dose- 50.11 3 months post 2nd dose- 50.81 6 months post 2nd dose- 46.27 Anti- spike GMT declined by only 8% at 6 months compared to peak titer. Seropositivity (%) (SARS-CoV-2 naïve cohorts) 21 days post 2nd dose- 77 3 months post 2nd dose- 55.7 6 months post 2nd dose- 37.7 |
Not mentioned in study | Covaxin showed lower seropositivity and anti-Spike GMT compared to Covishield at all time points but with much less decline from peak titers at 6 months after 2nd dose. Breakthrough infection rates were similar in the 2 vaccines Covishield (54/407, 13.3%) vs Covaxin (10/74, 13.5%). |
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| 407 | Covishield | GMT (AU/ml) (SARS-CoV-2 naïve cohorts) 21 days post 1st dose- 61.93 21 days post 2nd dose- 132.88 3 months post 2nd dose- 112.78 6 months post 2nd dose- 73.83 GMT declined by 44% at 6 months compared to peak titer. Seropositivity (%) (SARS-CoV-2 naïve cohorts) 21 days post 2nd dose-98.7 3 months post 2nd dose- 92.6 6 months post 2nd dose- 22.1 |
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| Sharma et al. (29) | Cross-sectional study of Health care workers | 168(Atleast 1 dose) 154 (Both doses) |
Covaxin | None performed | 33 infections of 168 (19.6%) Breakthrough 24 of 154 (15.6%) |
History of prior infection with COVID-19 and atleast one vaccine dose was significantly protective of breakthrough infections. | |||||||||||||
| 157(Atleast one dose) 125 (Both doses) |
Covishield | 24 infections of 157 (15.3%) Breakthrough 13 of 125 (10.4%) |
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| Dash et al. (32) | Cross-sectional study including breakthrough cases | 35 | Covaxin | Anti-Spike receptor binding domain IgG Ab - 27 (77.1%) Ab titer- 213.5 AU/ml [interquartile range (IQR)537.5] |
Symptomatic-29 (82.9%) Asymptomatic- 6 (17.1%) Hospitalized -3 (8.6%) |
Seropositivity in Covishield vaccinees was significantly higher than Covaxin. Among the 27 (breakthrough infection) hospitalised vaccinees, 1 (Covishield recipient) died. |
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| 239 | Covishield | Anti-Spike receptor binding domain IgG Ab - 231 (96.7%) Ab titer- 647.5 AU/ml (IQR: 1645.1), |
Symptomatic-199 (83.3%) Asymptomatic – 40 (16.7%) Hospitalized – 24 (10%) |
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| Kumar et al. (35) | Prospective cohort study of health care workers | 44 | Covaxin | Increased induction of Type 1,2,17 and pro-inflammatory cytokines (IFN-γ, IL-1a,IL-1b, IL-2, IL-3, TNF-α, IL-4, IL-5,IL-6, IL-7 IL-10, IL-12, IL-13,IL-17A). Reduced synthesis of IL-25, IL-33, GM-CSF, Type 1 interferons. Increased plasma levels of chemokines (CCL4, CXCL1, CXCL2 and CX3CL1). Reduced levels of CXCL10. Significant correlations between IL-2, IL-17A, IL-4, IL-5 and NAb at baseline. |
Not mentioned in study | The effect of ‘Prime boost’ Covaxin on cytokine and chemokine profiles was studied at baseline(0) and after 1,2 and 3 months. Raised type 1,17 and pro-inflammatory cytokine levels show ‘immune memory induction’ while raised type 2 cytokines maybe attributed to vaccine adjuvant. Raised chemokines also show innate immunity induction. |
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| Yadav et al. (39) | Cross-sectional study | 17 | Covaxin vaccinees(28 days after 2nd dose) | Geometric mean titer (GMT) of serum against B.1- 187.5 (95% CI: 129.3–271.9), Beta- 61.57 (95%CI: 36.34–104.3) Delta - 68.97 (95%CI: 24.72–192.4) |
Not mentioned in study | Neutralization of sera by covaxin recipients was assessed and compared with sera of recovered patients against Beta and Delta variants. | |||||||||||||
| 20 | COVID recovered(5-20 weeks after infection) | GMT of sera against B.1 - 97.8 (95%CI: 61.2–156.2) Beta- 29.6 (95%CI: 13.4–65.0) Delta- 21.2 (95% CI: 6.4–70.1) |
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| Sapkal et al. (36) | Cross-sectional study | 42 | Covaxin | GMT of IgG: For S1-Receptor Binding domain protein- 2250 For N Protein- 3099 GMT-Nab by PRNT50 (for prototype D614G)- 337.5 GMT by PRNT50 (For the B.1.1.28.2 variant)- 175.7 |
Not mentioned in study | IgG levels and NAb activity were assessed and it was concluded that a 2 -dose BBV152 is effective against both B.1.1.28.2 variant and D614G prototype( which was used to develop Covaxin), compared to protection afforded by natural infection. | |||||||||||||
| Total (n=19) B.1.1.7 (n=2) B.1.351 (n=2) B.1.1.28.2 (n=2) B1 lineage (n=13) |
Convalescent sera (15–113 days after positive report). | GMT of IgG: For S1-Receptor Binding domain protein- 794.8 For N Protein- 4627 GMT NAb by PRNT50 (for prototype D614G)- 120.1 GMT by PRNT50 (For the B.1.1.28.2 variant)- 109.2 |
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| Sapkal et al. (37) | Cross-sectional study | 38 vaccine recipients | Nab titers by PRNT50 of vaccinee sera had comparable efficacy against UK variant of GR clade (mutant hCoV-19/India/20203522) as well as the hCoV-19/India/2020770 (used for developing Covaxin) belonging to G clade and hCoV- 19/India/2020Q111 belonging to O clade. Median ratio of 50% neutralization- 0.8 hCoV- 19/India/2020770 vs UK variant Median ratio of 50% neutralization- 0.9 hCoV- 19/India/2020770 vs hCoV- 19/India/2020Q111 |
Not mentioned in study | PRNT50 values from the different groups did not show any significant difference (P>0.05). | ||||||||||||||
| Yadav et al. (40) | Cross-sectional study involving various categories of Covaxin recipients | GMT of NAb (PRNT50) | Not mentioned in study | Neutralization was assessed against Delta, Delta AY.1 and B.1.617.3 compared with B.1 variant. NAb titers for BTI group was highest followed by CRV and CNV. In the CNV group, compared to B1, NAb titer against B.1.617.3 was lowest at a 1.88 reduction while Delta showed 1,29 reduction. The CRV and BTI groups also showed a similar pattern of reduction of B.1.617.3>Delta AY.1>Delta, although there were higher fold reductions in neutralization. The role of memory cells could explain the high titers observed in CRV and BTI groups compared to CNV group. Although titers against the new variants were reduced, some protection against severe disease could still be plausible. |
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| 42 | COVID-19 naïve vaccinees (CNV) | Delta | Delta AY.1 | B.1.617.3 | B1 | ||||||||||||||
| 241.6 (95% CI: 167.8–347.7) | 209.1 (95% CI: 146.5–298.3) | 165.3 (95% CI: 115.6–236.5) | 310.6 (95% CI: 222–434.6) | ||||||||||||||||
| 14 | COVID-19 recovered and vaccinated (CRV) | Delta | Delta AY.1 | B.1.617.3 | B1 | ||||||||||||||
| 328.6 (95% CI: 186.9–577.9) | 234.5 (95% CI: 138.7–396.4) | 217.8 (95% CI: 136.7–347.1) | 820.1 (95% CI: 469–1434) | ||||||||||||||||
| 30 | Breakthrough infections after vaccination (BTI) | Delta | Delta AY.1 | B.1.617.3 | B1 | ||||||||||||||
| 465.6 (95% CI: 213.2–1016) | 317.2 (95% CI: 125.5–801.4) | 259.7 (95% CI: 157.1– 429.4) | 896.6 (95% CI: 550.3–1461) | ||||||||||||||||
| Kumar et al. (41) | Cross-sectional study involving health care workers | 84 | SARS-COV-2 IgG proteins (AU/ml) | NAb % inhibition- | Not mentioned in study | A single dose of Covaxin administered to previously SARS-COV-2 infected individuals could elicit comparable humoral immune response to that seen in non-exposed individuals administered both doses of the vaccine. | |||||||||||||
| Vaccinees with no prior infection | Baseline | IgG N- 0.71 IgG S- 0.37 |
-1.43 | ||||||||||||||||
| Month 1 | IgG N- 2.4 IgG S- 2.3 |
9.2 | |||||||||||||||||
| Month 2 | IgG N- 56.3 IgG S- 86.7 |
68.9 | |||||||||||||||||
| 30 | Vaccinees with prior infection | Baseline | IgG N- 29.3 IgG S- 48.8 |
74.1 | |||||||||||||||
| Month 1 | IgG N- 78.6 IgG S- 167.2 |
95.8 | |||||||||||||||||
| Month 2 | IgG N- 95 IgG S- 211 |
94.5 | |||||||||||||||||
| Kant et al. (43) | Cross-sectional study involving 98 vaccine recipients | 18 | Vaccinees given Covishield + Covaxin | GMT S1-RBD ELISA titer | GMT N protein ELISA Titer | IgG (GMT) inactivated SARS-CoV-2 virus | NAb (PRNT50) GMT, Against B1/ Alpha/ Beta/ Delta |
Inj. Site Pain - 11.1% after 1st dose none after 2nd dose Pyrexia- 27.7% after 1st dose and 11.1% after 2nd dose Malaise- 33.3% after 1st dose and 5.5% after 2nd dose |
Pain at injection site was the most common local adverse effect while most common systemic adverse events were pyrexia and malaise. All adverse events in the Covaxin + Covishield group were comparable to either group alone. Covishield vaccinees were found to have the highest titers for GMT S1-RBD. The heterologous group had highest GMT N protein and IgG (GMT) to inactivated virus titer as well as highest levels of NAb (GMT) towards all the 4 variants. |
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| 1866 | 1145 | 171.4 |
B1- 539.4 Alpha- 396.1 Beta- 151 Delta- 241.2 |
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| 40 | Covishield vaccinees | 2260 | 353.7 | 111 |
B1- 162 Alpha- 122.7 Beta- 48.43 Delta- 51.99 |
Inj. Site pain- 5% after 1st dose 5% after 2nd dose Pyrexia- 20% after 1st dose and 15% after 2nd dose Malaise- 5% after 1st dose and 5% after 2nd dose |
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| 40 | Covaxin vaccinees | 710 | 742.4 | 86 |
B1- 156.6 Alpha- 112.4 Beta- 52.09 Delta- 54.37 |
Inj. Site pain - 7.5% after 1st dose 7.5% after 2nd Pyrexia- 30% after 1st dose and 15% after 2nd dose Malaise- 32.5% after 1st dose and 15% after 2nd dose |
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| Basavaraja et al. (27) | Prospective observational study | 9292 doses to 5986 vaccinees | Covishield | Not mentioned in study | Incidence rate of adverse events was 4.32%. 433 AE (409 expected as per factsheets) 94.22%- associated with immunization of which 78.98% related to vaccine products and 15.24% due to anxiety. |
Half (50.9%) vaccinees had a single AE, 34.9% had 2 AE’s while 8.6% reported 3 AE’s. Most of the AE’s followed the 1st dose of vaccination. Covishield vaccinees had mostly fever, injection site tenderness, pain and joint pain muscle aches, while Covaxin recipients had injection site pain, fever and 3 cases had giddiness which was not mentioned in factsheets. |
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| 2364 doses to 1749 vaccinees | Covaxin | Incidence rate of adverse events was 0.57%. 12 AE (9 expected as per factsheets) 8(66.6%)- associated with immunization of which none related to vaccine products and all related to anxiety. |
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| Choudhary et al. (28) | Longitudinal Cohort study involving Health Care workers | 308 | Covishield | Highest levels of spike >protein IgG observed in the 12th week (median=1299.5 AU/ml) (IQ:517.9-5019.2) falling to 637.2 AU/ml (IQ: 186.5–3,055.3) after 6 months. In unexposed seronegative individuals, 81.9% had seroconversion at 4 weeks after 1st dose. |
Out of 81 breakthrough infections, 37% were Covishield recipients. | Covishield vaccinees had significantly higher IgG Ab compared to Covaxin . There was a 2-fold reduction in spike Ab titers in Covishield while Covaxin vaccinees had a more drastic 4-fold reduction. |
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| 306 | Covaxin | Highest levels of spike protein IgG observed in the 12th week (Median= 342.7 AU/ml) (IQ: 76.1–892.8) falling to 95.1 AU/ml (IQ: 36.5–277.2) at 6 months. In unexposed seronegative individuals, 16.1% had seroconversion at 4 weeks after 1st dose. |
Out of 81 breakthrough infections, 63% were after Covaxin. | ||||||||||||||||
| Desai et al. (38) | Test negative case-control study | 1068 matched case-control pairs | Adjusted effectiveness of 2 doses of Covaxin against symptomatic RTPCR positive (tested atleast 2 weeks after 2nd dose) SARS-CoV-2 was 50% (95% CI 33-62) and if testing was at 4 weeks or more, the adjusted effectiveness was 46% (95% CI 22–62). At 6 weeks effectiveness rose to 57% (95% CI 21–76). If participants with prior infection were excluded the adjusted effectiveness was 47% (95% CI 29–61). | Not mentioned in study | This study was undertaken at a time of surge in cases during the second wave of COVID in India. The Delta variant was infamous for its immune evasion and might have been responsible for the lower efficacy compared to phase III trials conducted by Bharat Biotech. | ||||||||||||||
| Medigeshi et al. (42) | Cross-sectional study | Median duration from 2nd dose of either vaccine- 234 days | GMT of Focus reduction neutralization titer (FRNT50) |
Neutralisation titers above limit of quantification (1:20)Against Omicron | Not mentioned in study | Both Covaxin and Covishield vaccinees with no prior infection had a ~26-fold reduction in FRNT50 titers against Omicron compared to ancestral variant after 6 months. Those with prior infection had ~57-fold reduction. Significant reduction in neutralizing ability of both vaccines was observed but prior infection was associated with significantly high titers. Anti-nucleocapsid Ab wane in Covaxin vaccinees, however, those with prior infection sustain Ab for longer periods compared to Covishield. |
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| Ancesrtral | Delta | Omicron | |||||||||||||||||
| 20 | Only Covaxin | 380.4 | 164.7 | 14.3 | 5 out of 20 samples | ||||||||||||||
| 20 | Covaxin + previous infection | 806.1 | 260.2 | 14.12 | 6 out of 20 samples | ||||||||||||||
| 20 | Only Covishield | 379.3 | 11.9 | 14.7 | 5 out o 20 samples | ||||||||||||||
| 20 | Covishield + previous infection | 1526.2 | 358.1 | 26.3 | 9 out of 20 samples | ||||||||||||||
| Houshmand et al. (31) | Cross-sectional study | Side-effect intensity/incidence | |||||||||||||||||
| 578 | Covishield | 98.6 % had atleast one side effect. Highest intensity of almost all side effects |
No serious side-effects were reported for BBV152. Adenovirus-vector based vaccines were found to cause higher levels of side-effects attributable to cytokine/chemokine release compared to inactivated vaccines. 73.1% side-effects observed within 24 hours for all vaccines. |
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| 25 | Covaxin | 100% had atleast 1 side-effect. Local pain in the hand only side-effect of significant intensity. |
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| 426 | GAM-Covid-Vac | 93.2% had atleast 1 side-effect. Injection site pain, Fever, muscle pain common. |
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| 102 | BBIP-CorV | 87.3% had at least one side effect. Lowest intensity of almost all side effects |
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| Sapkal et al. (44) | 17 | CS/CV | S1-RBD IgG Ab titer- 4.13 fold reduction in GMT mean titer ratio of 1st and 6th month Reduction in Ratio of GMT of NAb at 1st and 6th month |
Not mentioned | Heterologous vaccinees had higher NAb titers despite significant fold reductions in titers 6 months after 2nd dose. Comparison with B.1 ancestral variant revealed that NAb titers were drastically low for omicron variant. |
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| B.1 (ancestral) | Alpha | Beta | Delta | ||||||||||||||||
| 7.17 | 6.98 | 7.19 | 5.75 | ||||||||||||||||
| Reduction in NAb titers in comparison with B.1 for different VOCs | |||||||||||||||||||
| Alpha | Beta | Delta | Omicron | ||||||||||||||||
| 1.28 | 3.43 | 1.75 | 19.16 | ||||||||||||||||
| 36 | Covishield | S1-RBD IgG Ab titer- 6.8 fold reduction in GMT mean titer ratio of 1st and 6th month Reduction in Ratio of GMT of Nab at 1st and 6th month |
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| B.1 (ancestral) | Alpha | Beta | Delta | ||||||||||||||||
| 2.87 | 3.51 | 2.76 | 1.96 | ||||||||||||||||
| Reduction in NAb titers in comparison with B.1 for different VOCs | |||||||||||||||||||
| Alpha | Beta | Delta | Omicron | ||||||||||||||||
| 1.63 | 3.43 | 2.27 | 23.15 | ||||||||||||||||
| 35 | Covaxin | S1-RBD IgG Ab titer- 4.87 fold reduction in GMT mean titer ratio of 1st and 6th month Reduction in Ratio of GMT of Nab at 1st and 6th month |
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| B.1 (ancestral) | Alpha | Beta | Delta | ||||||||||||||||
| 3.17 | 3.72 | 2.61 | 3.36 | ||||||||||||||||
| Reduction in NAb titers in comparison with B.1 for different VOCs | |||||||||||||||||||
| Alpha | Beta | Delta | Omicron | ||||||||||||||||
| 1.67 | 2.56 | 2.83 | 24.21 | ||||||||||||||||
| Malhotra et al. (33) | Retrospective cohort study involving previously infected HCWs | Estimated vaccine effectiveness against: | Full vaccination with BBV152 was associated with a good protective effect while partial vaccination was ineffective. Since most of the reinfections occurred during the Delta variant-induced 2nd wave, Covaxin accorded sufficient protection in pre-infected participants. |
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| Reinfection | Symptomatic reinfection | Asymptomatic reinfection | |||||||||||||||||
| 1089 | Fully vaccinated with Covaxin | 86% | 87% | 84% | |||||||||||||||
| 356 | Partially vaccinated with Covaxin | 12% | 16% | – | |||||||||||||||
| 472 | Unvaccinated | – | – | – | |||||||||||||||