Effectiveness of Covid-19 vaccines against symptomatic and asymptomatic SARS-CoV-2 infections in an urgent care setting.
Vaccine
; 41(4): 989-998, 2023 Jan 23.
Article
in English
| MEDLINE | ID: covidwho-2165925
ABSTRACT
BACKGROUND:
It is critical to monitor changes in vaccine effectiveness against COVID-19 outcomes for various vaccine products in different population subgroups.METHODS:
We conducted a retrospective study in patients ≥12 years who underwent testing for SARS-CoV-2 virus from April 14 through October 25, 2021, at urgent care centers in the New York metropolitan area. Patients self-reported vaccination status at the time of testing. We used a test-negative design to estimate vaccine effectiveness (VE) by comparing odds of a positive test for SARS-CoV-2 infection among vaccinated (n = 474,805), partially vaccinated (n = 87,834), and unvaccinated (n = 369,333) patients, adjusted for demographic factors and calendar time.RESULTS:
VE against symptomatic infection after 2 doses of mRNA vaccine was 96% (95% Confidence Interval 95%, 97%) in the pre-delta period and reduced to 79% (95% CI 77%, 81%) in the delta period. In the delta period, VE for 12-15-year-olds (85%; [95% CI 81%, 88%]) was higher compared to older age groups (<65% for all other age groups). VE estimates did not differ by sex and race/ethnicity. VE against symptomatic infection was the highest for individuals with a prior infection followed by full vaccination. VE against symptomatic infection after the 2-dose mRNA-1273 vaccine (82% [95% CI 80%, 84%]) was higher compared to the BNT162b2 vaccine (76% [95% CI 74%, 78%]) in the delta period. VE after 1-dose of the Ad26.COV2.S vaccine was the lowest compared to other vaccines (19% [95% CI 15%, 23%]) in the delta period.CONCLUSIONS:
VE against infection after two doses of the mRNA vaccines was high initially, but significantly reduced against the delta variant for both FDA-approved vaccines.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
COVID-19 Vaccines
/
COVID-19
Type of study:
Experimental Studies
/
Observational study
/
Prognostic study
/
Randomized controlled trials
Topics:
Vaccines
/
Variants
Limits:
Aged
/
Humans
Language:
English
Journal:
Vaccine
Year:
2023
Document Type:
Article
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