Change in covid-19 risk over time following vaccination with CoronaVac: test negative case-control study.
BMJ
; 377: e070102, 2022 06 13.
Article
in English
| MEDLINE | ID: covidwho-2213918
ABSTRACT
OBJECTIVE:
To estimate the change in odds of covid-19 over time following primary series completion of the inactivated whole virus vaccine CoronaVac (Sinovac Biotech) in São Paulo State, Brazil.DESIGN:
Test negative case-control study.SETTING:
Community testing for covid-19 in São Paulo State, Brazil.PARTICIPANTS:
Adults aged ≥18 years who were residents of São Paulo state, had received two doses of CoronaVac, did not have a laboratory confirmed SARS-CoV-2 infection before vaccination, and underwent reverse transcription polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 from 17 January to 14 December 2021. Cases were matched to test negative controls by age (in 5 year bands), municipality of residence, healthcare worker status, and epidemiological week of RT-PCR test. MAIN OUTCOMEMEASURES:
RT-PCR confirmed symptomatic covid-19 and associated hospital admissions and deaths. Conditional logistic regression was adjusted for sex, number of covid-19 associated comorbidities, race, and previous acute respiratory illness.RESULTS:
From 202 741 eligible people, 52 170 cases with symptomatic covid-19 and 69 115 test negative controls with covid-19 symptoms were formed into 43 257 matched sets. Adjusted odds ratios of symptomatic covid-19 increased with time since completion of the vaccination series. The increase in odds was greater in younger people and among healthcare workers, although sensitivity analyses suggested that this was in part due to bias. In addition, the adjusted odds ratios of covid-19 related hospital admission or death significantly increased with time compared with the odds 14-41 days after series completion from 1.25 (95% confidence interval 1.04 to 1.51) at 70-97 days up to 1.94 (1.41 to 2.67) from 182 days onwards.CONCLUSIONS:
Significant increases in the risk of moderate and severe covid-19 outcomes occurred three months after primary vaccination with CoronaVac among people aged 65 and older. These findings provide supportive evidence for the implementation of vaccine boosters in these populations who received this inactivated vaccine. Studies of waning should include analyses designed to uncover common biases.
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Vaccines
/
COVID-19
Type of study:
Diagnostic study
/
Observational study
/
Prognostic study
Topics:
Vaccines
Limits:
Adolescent
/
Adult
/
Humans
Country/Region as subject:
South America
/
Brazil
Language:
English
Journal:
BMJ
Journal subject:
Medicine
Year:
2022
Document Type:
Article
Affiliation country:
Bmj-2022-070102
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