Public Health Watch: Infection Rare in Vaccinated Healthcare Workers

Greatest risk for infection among vaccinated may be at home rather than at work, researchers say.

Vaccinated healthcare workers remain at risk for SARS-CoV-2 infection, particularly as the Delta variant of the virus continues to spread, according to a study published September 1 by JAMA Network Open.

Though, thankfully, the risk is extremely low, particularly in comparison with unvaccinated staff, the researchers said.

The results are striking, given that the vast majority of clinicians in the US have been vaccinated or plan to get the shot. According to a survey conducted by the American Nurses Association, 88% of nurses are either vaccinated or plan to get vaccinated.

A similar poll by the American Medical Association found that 96% of physicians nationally have either received the COVID-19 vaccine or plan to do so.

Yet, despite these figures, a perception exists, at least in the US, that healthcare workers are vaccine-hesitant due to, among other issues, the rapid development of the shots.

If there are any vaccine-hesitant among the clinician population across the country, the findings of the JAMA Network Open analysis, which are based on an analysis of data on 5,312 fully vaccinated staff and 690 unvaccinated personnel at the Hadassah-Hebrew University Medical Center in Jerusalem, should change minds. Those vaccinated all received 2 doses of the BNT162b2 mRNA shot (Pfizer-BioNTech) before March 31. This particularly vaccine has been the primary option in Israel since the shots first became available.

Of the 5312 vaccinated staff, 27 (0.5%) later had positive test results for SARS-CoV-2, according to the study. In comparison, 69 of the 690 unvaccinated personnel (10%) tested positive, though data was only available for 63 of them, the researchers said.

Significantly, though, 15 of the 27 positive cases among vaccinated healthcare workers were traced to exposure to infected members of their household, as opposed to patients at work, suggesting that occupational risk may be lower, due at least in part to widespread use of personal protective equipment (PPE). This was true even for those staff engaged in patient care in COVID-19 wards, the study found.

“The vaccine’s protection is not absolute when the exposure is close and prolonged,” study coauthor Yonatan Oster, MD, a researcher in the Department of Clinical Microbiology and Infectious Diseases at Hadassah-Hebrew University Medical Center, told Contagion. “Such is the case with positive household members, the risk of getting infected is high. We think that these findings should change … policy for quarantine of vaccinated persons with such an exposure.”

Indeed, interestingly, risk for exposure to positive SARS-CoV-2-positive household members among fully vaccinated staffers was 2-fold higher (OR: 2.03; 95% CI, 0.74-5.62) compared with their unvaccinated peers. In addition, the number of positive household members per case was higher in the fully vaccinated staff group (2.7) than in the unvaccinated group (1.7), though this difference was not statistically significant.

Overall, only 1 of 27 fully vaccinated staff and 2 of 63 unvaccinated personnel were hospitalized due to infection, and none died.

“We don’t have experience with the Moderna vaccine, as very few doses were given in Israel,” Oster said. However, “the data in the literature suggests that these conclusions apply also to Moderna vaccines.”