Effectiveness of COVID-19 Vaccines against Delta (B.1.617.2) Variant: A Systematic Review and Meta-Analysis of Clinical Studies

Pormohammad, Ali; Zarei, Mohammad; Ghorbani, Saied; Mohammadi, Mehdi; Neshin, Saeideh Aghayari Sheikh; Khatami, Alireza; Turner, Diana; Djalalinia, Shirin; Mousavi, S. Hossein; Mardani-Fard, Heydar Ali; Kasaeian, Amir; Turner, Raymond J.

doi:10.3390/vaccines10010023

Cited by 54 publications

(41 citation statements)

References 48 publications

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“…The VE against severe disease requiring hospitalization was quite high, even when the delta variant was dominant. The adjusted VE against COVID-19-related hospitalization was 98% (95% CI: 85–99%) in our study ( Table S1 ), which is similar to the pooled VE against severe outcomes after two doses reported in a recent meta-analysis of 98.5% (95% CI: 95–99%) [ 29 ]. These results suggest that the mRNA vaccines help prevent severe COVID-19 breakthrough infection.…”

Section: Discussionsupporting

confidence: 89%

Real-World Effectiveness of the mRNA COVID-19 Vaccines in Japan: A Case–Control Study

et al. 2022

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The real-world effectiveness of the coronavirus disease 2019 (COVID-19) vaccines in Japan remains unclear. This case–control study evaluated the vaccine effectiveness (VE) of two doses of mRNA vaccine, BNT162b2 or mRNA-1273, against the delta (B.1.617.2) variant in the Japanese general population in the period June–September 2021. Individuals in close contact with COVID-19 patients were tested using polymerase chain reaction (PCR). A self-administered questionnaire evaluated vaccination status, demographic data, underlying medical conditions, lifestyle, personal protective health behaviors, and living environment. Two vaccine doses were reported by 11.6% of cases (n = 389) and 35.2% of controls (n = 179). Compared with controls, cases were younger and had a lower proportion who always performed handwashing for ≥20 s, a higher proportion of alcohol consumers, and a lower proportion of individuals living in single-family homes or with commuting family members. After adjusting for these confounding factors and day of PCR testing by multivariate logistic regression analysis, the VE in the period June–July (delta variant proportion 45%) was 92% and 79% in the period August–September (delta variant proportion 89%). The adjusted VE for homestay, hotel-based isolation and quarantine, and hospitalization was 78%, 77%, and 97%, respectively. Despite declining slightly, VE against hospitalization remained robust for ~3 months after the second dose. Vaccination policymaking will require longer-term monitoring of VE against new variants.

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Section: Discussionsupporting

confidence: 89%

Real-World Effectiveness of the mRNA COVID-19 Vaccines in Japan: A Case–Control Study

et al. 2022

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“…To our knowledge, there are some studies evaluating the VE of COVID-19 vaccines against VOC [ 20 – 23 ]. Some relevant systematic review or meta-analysis about COVID-19 vaccines against Delta variant have been published to date [ 24 – 26 ], which did not include many recent studies as the most recent retrieval date was October 2021. Therefore, to gain insight in the VE of COVID-19 vaccines against five kinds of VOC, we conducted a comprehensive systematic review and meta-analysis including both RCTs and observational studies.…”

Section: Introductionmentioning

confidence: 99%

Effectiveness of COVID-19 vaccines against SARS-CoV-2 variants of concern: a systematic review and meta-analysis

Zeng

Gao

Zhou

et al. 2022

BMC Med

215

102

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Background It was urgent and necessary to synthesize the evidence for vaccine effectiveness (VE) against SARS-CoV-2 variants of concern (VOC). We conducted a systematic review and meta-analysis to provide a comprehensive overview of the effectiveness profile of COVID-19 vaccines against VOC. Methods Published randomized controlled trials (RCTs), cohort studies, and case-control studies that evaluated the VE against VOC (Alpha, Beta, Gamma, Delta, or Omicron) were searched until 4 March 2022. Pooled estimates and 95% confidence intervals (CIs) were calculated using random-effects meta-analysis. VE was defined as (1-estimate). Results Eleven RCTs (161,388 participants), 20 cohort studies (52,782,321 participants), and 26 case-control studies (2,584,732 cases) were included. Eleven COVID-19 vaccines (mRNA-1273, BNT162b2, ChAdOx1, Ad26.COV2.S, NVX-CoV2373, BBV152, CoronaVac, BBIBP-CorV, SCB-2019, CVnCoV, and HB02) were included in this analysis. Full vaccination was effective against Alpha, Beta, Gamma, Delta, and Omicron variants, with VE of 88.0% (95% CI, 83.0–91.5), 73.0% (95% CI, 64.3–79.5), 63.0% (95% CI, 47.9–73.7), 77.8% (95% CI, 72.7–82.0), and 55.9% (95% CI, 40.9–67.0), respectively. Booster vaccination was more effective against Delta and Omicron variants, with VE of 95.5% (95% CI, 94.2–96.5) and 80.8% (95% CI, 58.6–91.1), respectively. mRNA vaccines (mRNA-1273/BNT162b2) seemed to have higher VE against VOC over others; significant interactions (pinteraction < 0.10) were observed between VE and vaccine type (mRNA vaccines vs. not mRNA vaccines). Conclusions Full vaccination of COVID-19 vaccines is highly effective against Alpha variant, and moderate effective against Beta, Gamma, and Delta variants. Booster vaccination is more effective against Delta and Omicron variants. mRNA vaccines seem to have higher VE against Alpha, Beta, Gamma, and Delta variants over others.

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“…Currently, B.1.617.2 (delta) and B.1.1.529 (omicron), the highly transmissible SARS-CoV-2 variants of concern, have brought new waves of infection worldwide and have accounted for breakthrough infections owing to their reduced sensitivity to the currently available vaccines. 17 Although vaccine effectiveness has been reported in real-world studies, 18 clinical efficacy against the prevalent delta variant of concern has been reported for only two vaccines in two randomized, controlled phase 3 trials. In one trial, the BBV152 vaccine (Bharat Biotech International) was shown to have an efficacy of 65.2%, 5 and in another, the SCB-2019 vaccine was shown to have an efficacy of 78.7%.…”

mentioning

confidence: 99%

Efficacy and Safety of the RBD-Dimer–Based Covid-19 Vaccine ZF2001 in Adults

Dai

Gao

Tao³

et al. 2022

N Engl J Med

197

159

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Background The ZF2001 vaccine, which contains a dimeric form of the receptor-binding domain of severe acute respiratory syndrome coronavirus 2 and aluminum hydroxide as an adjuvant, was shown to be safe, with an acceptable side-effect profile, and immunogenic in adults in phase 1 and 2 clinical trials. Methods We conducted a randomized, double-blind, placebo-controlled, phase 3 trial to investigate the efficacy and confirm the safety of ZF2001. The trial was performed at 31 clinical centers across Uzbekistan, Indonesia, Pakistan, and Ecuador; an additional center in China was included in the safety analysis only. Adult participants (≥18 years of age) were randomly assigned in a 1:1 ratio to receive a total of three 25-μg doses (30 days apart) of ZF2001 or placebo. The primary end point was the occurrence of symptomatic coronavirus disease 2019 (Covid-19), as confirmed on polymerase-chain-reaction assay, at least 7 days after receipt of the third dose. A key secondary efficacy end point was the occurrence of severe-to-critical Covid-19 (including Covid-19–related death) at least 7 days after receipt of the third dose. Results Between December 12, 2020, and December 15, 2021, a total of 28,873 participants received at least one dose of ZF2001 or placebo and were included in the safety analysis; 25,193 participants who had completed the three-dose regimen, for whom there were approximately 6 months of follow-up data, were included in the updated primary efficacy analysis that was conducted at the second data cutoff date of December 15, 2021. In the updated analysis, primary end-point cases were reported in 158 of 12,625 participants in the ZF2001 group and in 580 of 12,568 participants in the placebo group, for a vaccine efficacy of 75.7% (95% confidence interval [CI], 71.0 to 79.8). Severe-to-critical Covid-19 occurred in 6 participants in the ZF2001 group and in 43 in the placebo group, for a vaccine efficacy of 87.6% (95% CI, 70.6 to 95.7); Covid-19–related death occurred in 2 and 12 participants, respectively, for a vaccine efficacy of 86.5% (95% CI, 38.9 to 98.5). The incidence of adverse events and serious adverse events was balanced in the two groups, and there were no vaccine-related deaths. Most adverse reactions (98.5%) were of grade 1 or 2. Conclusions In a large cohort of adults, the ZF2001 vaccine was shown to be safe and effective against symptomatic and severe-to-critical Covid-19 for at least 6 months after full vaccination. (Funded by the National Science and Technology Major Project and others; ClinicalTrials.gov number, NCT04646590 .)

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Effectiveness of COVID-19 Vaccines against Delta (B.1.617.2) Variant: A Systematic Review and Meta-Analysis of Clinical Studies

Cited by 54 publications

References 48 publications

Real-World Effectiveness of the mRNA COVID-19 Vaccines in Japan: A Case–Control Study

Real-World Effectiveness of the mRNA COVID-19 Vaccines in Japan: A Case–Control Study

Effectiveness of COVID-19 vaccines against SARS-CoV-2 variants of concern: a systematic review and meta-analysis

Efficacy and Safety of the RBD-Dimer–Based Covid-19 Vaccine ZF2001 in Adults

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