Effectiveness of COVID-19 vaccines against symptomatic SARS-CoV-2 infection and severe outcomes with variants of concern in Ontario

Abstract

volution of the SARS-CoV-2 virus over the course of the COVID-19 pandemic has resulted in the emergence of four variants of concern (VOC)-Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1) and Delta (B.1.617.2)-to date. Alpha was first detected in the

The effectiveness of mRNA‐1273 vaccine against COVID‐19 caused by Delta variant: A systematic review and meta‐analysis

“…The meta-analysis of three studies 4-6 revealed significant protective effect against RT-PCR confirmed COVID-19 caused by Delta variant 21 days or more after the first dose of mRNA-1273 vaccine (pooled OR = 0.34; 95% CI: 0.33-0.35; I 2 = 0%; p = 0.66; Figure 2A), where pooled estimate indicates vaccine effectiveness of 66% (95% CI: 65%-67%). In addition, the meta-analysis of four studies 4,5,7,8 revealed even higher significant protective effect against RT-PCR confirmed COVID-19 caused by Delta variant 14 days or more after the second dose of mRNA-1273 vaccine (pooled OR = 0.09; 95% CI: 0.05-0.16; I 2 = 94%; p = 0.01; Figure 2B), where pooled estimate indicates vaccine effectiveness of 91% (95% CI: 84%-95%).…”

Antibody responses against SARS-CoV-2 variants induced by four different SARS-CoV-2 vaccines

“…Data visualization and Spearman's rank correlation analyses were performed in GraphPad Prism software (version 8.3). The reported vaccine efficacy data has been taken from current literature (Table S2) [2,3,5,[14][15][16][17][18]20,[22][23][24][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52].…”

Decoupling of omicron variant infections and severe COVID-19

“…2,3 Nevertheless, real-world data showed more than 80% effectiveness against severe disease and hospitalisations. 4,5 Although preliminary evidence suggests booster doses might enhance protection against omicron, 6 studies are underway to fully determine vaccine effectiveness. Given the natural lag between infection and severe outcomes, we await further data on omicron for effectiveness of vaccinations in preventing severe disease-the key intended outcome of vaccination.…”

“… 2 , 3 Nevertheless, real-world data showed more than 80% effectiveness against severe disease and hospitalisations. 4 , 5 …”