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Effectiveness of BNT162b2 and mRNA-1273 covid-19 vaccines against symptomatic SARS-CoV-2 infection and severe covid-19 outcomes in Ontario, Canada: test negative design study.
Chung, Hannah; He, Siyi; Nasreen, Sharifa; Sundaram, Maria E; Buchan, Sarah A; Wilson, Sarah E; Chen, Branson; Calzavara, Andrew; Fell, Deshayne B; Austin, Peter C; Wilson, Kumanan; Schwartz, Kevin L; Brown, Kevin A; Gubbay, Jonathan B; Basta, Nicole E; Mahmud, Salaheddin M; Righolt, Christiaan H; Svenson, Lawrence W; MacDonald, Shannon E; Janjua, Naveed Z; Tadrous, Mina; Kwong, Jeffrey C.
  • Chung H; ICES, Toronto, ON, Canada.
  • He S; ICES, Toronto, ON, Canada.
  • Nasreen S; ICES, Toronto, ON, Canada.
  • Sundaram ME; ICES, Toronto, ON, Canada.
  • Buchan SA; Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
  • Wilson SE; ICES, Toronto, ON, Canada.
  • Chen B; Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
  • Calzavara A; Public Health Ontario, ON, Canada.
  • Fell DB; Centre for Vaccine Preventable Diseases, University of Toronto, Toronto, ON, Canada.
  • Austin PC; ICES, Toronto, ON, Canada.
  • Wilson K; Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
  • Schwartz KL; Public Health Ontario, ON, Canada.
  • Brown KA; Centre for Vaccine Preventable Diseases, University of Toronto, Toronto, ON, Canada.
  • Gubbay JB; ICES, Toronto, ON, Canada.
  • Basta NE; ICES, Toronto, ON, Canada.
  • Mahmud SM; ICES, Toronto, ON, Canada.
  • Righolt CH; School of Epidemiology and Public Health, University of Ottawa, ON, Canada.
  • Svenson LW; Children's Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada.
  • MacDonald SE; ICES, Toronto, ON, Canada.
  • Janjua NZ; Institute of Health Policy, Management, and Evaluation, University of Toronto, Toronto, ON, Canada.
  • Tadrous M; School of Epidemiology and Public Health, University of Ottawa, ON, Canada.
  • Kwong JC; Bruyère and Ottawa Hospital Research Institutes, Ottawa, ON, Canada.
BMJ ; 374: n1943, 2021 08 20.
Article in English | MEDLINE | ID: covidwho-1367424
ABSTRACT

OBJECTIVE:

To estimate the effectiveness of mRNA covid-19 vaccines against symptomatic infection and severe outcomes (hospital admission or death).

DESIGN:

Test negative design study.

SETTING:

Ontario, Canada between 14 December 2020 and 19 April 2021.

PARTICIPANTS:

324 033 community dwelling people aged ≥16 years who had symptoms of covid-19 and were tested for SARS-CoV-2.

INTERVENTIONS:

BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) vaccine. MAIN OUTCOME

MEASURES:

Laboratory confirmed SARS-CoV-2 by reverse transcription polymerase chain reaction (RT-PCR) and hospital admissions and deaths associated with SARS-CoV-2 infection. Multivariable logistic regression was adjusted for personal and clinical characteristics associated with SARS-CoV-2 and vaccine receipt to estimate vaccine effectiveness against symptomatic infection and severe outcomes.

RESULTS:

Of 324 033 people with symptoms, 53 270 (16.4%) were positive for SARS-CoV-2 and 21 272 (6.6%) received at least one dose of vaccine. Among participants who tested positive, 2479 (4.7%) were admitted to hospital or died. Vaccine effectiveness against symptomatic infection observed ≥14 days after one dose was 60% (95% confidence interval 57% to 64%), increasing from 48% (41% to 54%) at 14-20 days after one dose to 71% (63% to 78%) at 35-41 days. Vaccine effectiveness observed ≥7 days after two doses was 91% (89% to 93%). Vaccine effectiveness against hospital admission or death observed ≥14 days after one dose was 70% (60% to 77%), increasing from 62% (44% to 75%) at 14-20 days to 91% (73% to 97%) at ≥35 days, whereas vaccine effectiveness observed ≥7 days after two doses was 98% (88% to 100%). For adults aged ≥70 years, vaccine effectiveness estimates were observed to be lower for intervals shortly after one dose but were comparable to those for younger people for all intervals after 28 days. After two doses, high vaccine effectiveness was observed against variants with the E484K mutation.

CONCLUSIONS:

Two doses of mRNA covid-19 vaccines were observed to be highly effective against symptomatic infection and severe outcomes. Vaccine effectiveness of one dose was observed to be lower, particularly for older adults shortly after the first dose.
Subject(s)

Full text: Available Collection: International databases Database: MEDLINE Main subject: Patient Admission / COVID-19 Vaccines / COVID-19 Nucleic Acid Testing / COVID-19 Type of study: Diagnostic study Limits: Adolescent / Adult / Aged / Female / Humans / Male / Middle aged / Young adult Country/Region as subject: North America Language: English Journal: BMJ Journal subject: Medicine Year: 2021 Document Type: Article Affiliation country: Bmj.n1943

Full text: Available Collection: International databases Database: MEDLINE Main subject: Patient Admission / COVID-19 Vaccines / COVID-19 Nucleic Acid Testing / COVID-19 Type of study: Diagnostic study Limits: Adolescent / Adult / Aged / Female / Humans / Male / Middle aged / Young adult Country/Region as subject: North America Language: English Journal: BMJ Journal subject: Medicine Year: 2021 Document Type: Article Affiliation country: Bmj.n1943