Asymptomatic, symptomatic COVID-19 infections in HCWs before, after vaccination

Editor's Note

In this study, researchers from the University of California, Irvine, found a rapid and sustained decline in COVID-19 symptomatic and asymptomatic infections in healthcare workers (HCWs) after vaccination.

Of 10,188 HCWs included in the study, 58% received a first dose within 2 weeks of when vaccinations started, and 70% within 4 weeks.

After HCWs began getting second doses, daily HCW cases fell 55% after week 1, 84% after week 2, and 94% after week 3.

Most HCWs with COVID-19 who were identified by asymptomatic testing (81%) reported having symptoms at the posttest interview. Many dismissed symptoms in real-time as common ailments, but recognized them as COVID-19 symptoms in hindsight.

The findings are consistent with experience with other viral respiratory infections, such as influenza and measles, in which vaccination reduces overall infection rates, viral shedding, and both symptomatic and asymptomatic transmission, the researchers note.