Your browser doesn't support javascript.
Effectiveness of COVID-19 vaccines against symptomatic SARS-CoV-2 infection and severe outcomes with variants of concern in Ontario.
Nasreen, Sharifa; Chung, Hannah; He, Siyi; Brown, Kevin A; Gubbay, Jonathan B; Buchan, Sarah A; Fell, Deshayne B; Austin, Peter C; Schwartz, Kevin L; Sundaram, Maria E; Calzavara, Andrew; Chen, Branson; Tadrous, Mina; Wilson, Kumanan; Wilson, Sarah E; Kwong, Jeffrey C.
  • Nasreen S; ICES, Toronto, Ontario, Canada.
  • Chung H; Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
  • He S; ICES, Toronto, Ontario, Canada.
  • Brown KA; ICES, Toronto, Ontario, Canada.
  • Gubbay JB; ICES, Toronto, Ontario, Canada.
  • Buchan SA; Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
  • Fell DB; Public Health Ontario, Toronto, Ontario, Canada.
  • Austin PC; Public Health Ontario, Toronto, Ontario, Canada.
  • Schwartz KL; ICES, Toronto, Ontario, Canada.
  • Sundaram ME; Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
  • Calzavara A; Public Health Ontario, Toronto, Ontario, Canada.
  • Chen B; Centre for Vaccine Preventable Diseases, University of Toronto, Toronto, Ontario, Canada.
  • Tadrous M; ICES, Toronto, Ontario, Canada.
  • Wilson K; School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada.
  • Wilson SE; Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada.
  • Kwong JC; ICES, Toronto, Ontario, Canada.
Nat Microbiol ; 7(3): 379-385, 2022 03.
Article in English | MEDLINE | ID: covidwho-1671571
ABSTRACT
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.
Subject(s)

Full text: Available Collection: International databases Database: MEDLINE Main subject: SARS-CoV-2 / COVID-19 Type of study: Diagnostic study / Prognostic study Topics: Vaccines / Variants Limits: Adolescent / Adult / Aged / Female / Humans / Male / Middle aged / Young adult Country/Region as subject: North America Language: English Journal: Nat Microbiol Year: 2022 Document Type: Article Affiliation country: S41564-021-01053-0

Full text: Available Collection: International databases Database: MEDLINE Main subject: SARS-CoV-2 / COVID-19 Type of study: Diagnostic study / Prognostic study Topics: Vaccines / Variants Limits: Adolescent / Adult / Aged / Female / Humans / Male / Middle aged / Young adult Country/Region as subject: North America Language: English Journal: Nat Microbiol Year: 2022 Document Type: Article Affiliation country: S41564-021-01053-0