A spring 2021 study has found nearly 20 times the rate of COVID-19 infection in unvaccinated healthcare staff, plus signs that transmission clusters were linked to those workers.
The results mirror recent nursing home studies that have found similar evidence to support COVID-19 vaccination.
Investigators examined the incidence and clinical characteristics of COVID-19 in more than 5,600 personnel at the Cleveland Veterans Administration Medical Center from February 1, 2021, through May 15, 2021. COVID-19 cases were confirmed using nasal swab samples and reverse transcriptase polymerase chain reaction tests.
Overall, fully vaccinated personnel were 19 times less likely than unvaccinated personnel to be diagnosed with COVID-19. In 14 weeks of follow-up, 6% of 1,408 the unvaccinated employees were diagnosed with COVID-19 versus 0.3% of 4,222 vaccinated employees, reported senior author Curtis J. Donskey, M.D., and colleagues.
The vaccinated workers who became infected had mild cases with no hospitalizations. They all reported being in situations that had put them at high risk of contagion. Five said that they had been exposed to infected family members, two said they were exposed in the community, and one was exposed to an unvaccinated coworker with COVID-19.
Close and frequent contact with infected, unvaccinated individuals has been shown to present a substantial risk to vaccinated individuals, the authors noted. In fact, unvaccinated workers in the Cleveland VA Medical Center were the suspected source for four clusters of infections involving 17 employees, the investigators reported.
The results not only suggest that vaccinated individuals should continue to avoid SARS-CoV-2 exposure, but “highlight the potential for adverse consequences when personnel decline SARS-CoV-2 vaccination,” the authors wrote.
Similar nursing home study findings
The authors of two recently published nursing home studies came to similar conclusions. A study in 78 Chicago facilities found that most fully vaccinated residents and staff members were not infected by outbreaks following the vaccine rollout. And in one Kentucky nursing home that suffered a March outbreak, unvaccinated residents had triple the rate of COVID-19 infections when compared with their vaccinated peers.
The authors of the Cleveland VA study noted additional risks for unvaccinated employees who did not develop COVID-19. Several unvaccinated individuals missed work due to quarantine after higher-risk COVID-19 exposures. (The hospital does not require quarantine for vaccinated individuals.)
The authors suggest that highlighting transmission risk and days of work missed due to quarantine might serve as an incentive for vaccine-hesitant individuals to get the shot.
The study also tracked COVID-19 gene variants of concern. Full findings were published in the Cambridge University Press.