Unvaccinated had 667% higher risk of infection from household transmission than fully vaccinated.
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Only 50% of vaccinated healthcare workers who were COVID-positive were symptomatic.
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Vaccine provides two modes of protection: decreased infection and symptomatic infection.
Abstract
Objective
To determine the impact of COVID-19 vaccination on infection rates in healthcare workers (HCWs) with a household exposure.
Methods
Retrospective cohort study 8410 HCWs (400 fully vaccinated, 1645 partially vaccinated, 6365 unvaccinated), employed by a large integrated healthcare system in the southeastern United States, tested for SARS-CoV-2 between January 1 and February 26, 2021.
Results
Benefit of vaccination persisted even with household exposure, with unvaccinated HCWs being 3.7 to 7.7 times more likely to be infected than partially or fully vaccinated HCW with positive household contacts respectively (partial OR = 3.73, 95% CI 2.17 – 6.47; full OR = 7.67, CI 2.75 – 21.35). Whereas 89.4% of unvaccinated COVID-positive HCWs with known household exposures were symptomatic, 50% of fully vaccinated HCWs had symptoms, reducing risk of secondary spread from and between HCWs.
Conclusions
COVID-19 vaccination provided protection against infection even amongst healthcare workers with close household contact, and after adjusting for community prevalence.
