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

2022; Nature Portfolio; Volume: 7; Issue: 3 Linguagem: Inglês

10.1038/s41564-021-01053-0

2058-5276

Sharifa Nasreen, Hannah Chung, Siyi He, Kevin A. Brown, Jonathan B. Gubbay, Sarah A. Buchan, Deshayne B. Fell, Peter C. Austin, Kevin L. Schwartz, Maria E. Sundaram, Andrew Calzavara, Branson Chen, Mina Tadrous, Kumanan Wilson, Sarah E. Wilson, Jeffrey C. Kwong,

COVID-19 Clinical Research Studies

SARS-CoV-2 variants of concern (VOC) are more transmissible and may have the potential for increased disease severity and decreased vaccine effectiveness. We estimated the effectiveness of BNT162b2 (Pfizer-BioNTech Comirnaty), mRNA-1273 (Moderna Spikevax) and ChAdOx1 (AstraZeneca Vaxzevria) vaccines against symptomatic SARS-CoV-2 infection and COVID-19 hospitalization or death caused by the Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1) and Delta (B.1.617.2) VOC in Ontario, Canada, using a test-negative design study. We identified 682,071 symptomatic community-dwelling individuals who were tested for SARS-CoV-2, and 15,269 individuals with a COVID-19 hospitalization or death. Effectiveness against symptomatic infection ≥7 d after two doses was 89–92% against Alpha, 87% against Beta, 88% against Gamma, 82–89% against Beta/Gamma and 87–95% against Delta across vaccine products. The corresponding estimates ≥14 d after one dose were lower. Effectiveness estimates against hospitalization or death were similar to or higher than against symptomatic infection. Effectiveness against symptomatic infection was generally lower for older adults (≥60 years) than for younger adults (<60 years) for most of the VOC–vaccine combinations. Our findings suggest that jurisdictions facing vaccine supply constraints may benefit from delaying the second dose in younger individuals to more rapidly achieve greater overall population protection; however, older adults would likely benefit most from minimizing the delay in receiving the second dose to achieve adequate protection against VOC. Analysis of the effectiveness of three vaccines to protect against symptomatic SARS-CoV-2 infection and severe outcomes caused by Alpha, Beta, Gamma and Delta variants in Ontario, Canada, suggests that a single dose provides considerable protection, two doses provide even higher protection, and effectiveness against hospitalization or death is similar to or higher than against symptomatic infection.