Shiloh
Editor, Senior Moderator
Source: https://www.bmj.com/content/374/bmj.n1943
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
BMJ 2021; 374 doi: https://doi.org/10.1136/bmj.n1943 (Published 20 August 2021) Cite this as: BMJ 2021;374:n1943
Hannah Chung, associate research methodologist1, Siyi He, research analyst1, Sharifa Nasreen, postdoctoral fellow1, Maria E Sundaram, postdoctoral fellow12, Sarah A Buchan, scientist and assistant professor1234, Sarah E Wilson, medical epidemiologist and assistant professor1234, Branson Chen, senior health information analyst1, Andrew Calzavara, associate research methodologist1, Deshayne B Fell, scientist and associate professor156, Peter C Austin, senior scientist and professor17, Kumanan Wilson, senior scientist and professor589, Kevin L Schwartz, infection prevention and control physician and assistant professor123, Kevin A Brown, scientist and assistant professor123, Jonathan B Gubbay, medical microbiologist and associate professor310, Nicole E Basta, associate professor11, Salaheddin M Mahmud, director and professor12, Christiaan H Righolt, analytics manager12, Lawrence W Svenson, provincial health analytics officer and associate professor13141516, Shannon E MacDonald, associate professor1517, Naveed Z Janjua, senior scientist and clinical professor1819, Mina Tadrous, scientist and assistant professor12021, Jeffrey C Kwong, senior scientist and professor12342223 on behalf of the Canadian Immunization Research Network (CIRN) Provincial Collaborative Network (PCN) Investigators
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...
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
BMJ 2021; 374 doi: https://doi.org/10.1136/bmj.n1943 (Published 20 August 2021) Cite this as: BMJ 2021;374:n1943
Hannah Chung, associate research methodologist1, Siyi He, research analyst1, Sharifa Nasreen, postdoctoral fellow1, Maria E Sundaram, postdoctoral fellow12, Sarah A Buchan, scientist and assistant professor1234, Sarah E Wilson, medical epidemiologist and assistant professor1234, Branson Chen, senior health information analyst1, Andrew Calzavara, associate research methodologist1, Deshayne B Fell, scientist and associate professor156, Peter C Austin, senior scientist and professor17, Kumanan Wilson, senior scientist and professor589, Kevin L Schwartz, infection prevention and control physician and assistant professor123, Kevin A Brown, scientist and assistant professor123, Jonathan B Gubbay, medical microbiologist and associate professor310, Nicole E Basta, associate professor11, Salaheddin M Mahmud, director and professor12, Christiaan H Righolt, analytics manager12, Lawrence W Svenson, provincial health analytics officer and associate professor13141516, Shannon E MacDonald, associate professor1517, Naveed Z Janjua, senior scientist and clinical professor1819, Mina Tadrous, scientist and assistant professor12021, Jeffrey C Kwong, senior scientist and professor12342223 on behalf of the Canadian Immunization Research Network (CIRN) Provincial Collaborative Network (PCN) Investigators
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...