Exposure to COVID-Positive Household Members a Big Risk Factor for Vaccinated Healthcare Workers

Exposure to COVID-19-positive household members is a risk factor associated with infection among vaccinated healthcare workers.

The findings of the recent study suggested reconsideration of quarantining vaccinated people who have had significant exposure to household members who tested positive for the virus.

While mass vaccination of Israeli adults who received the BNT162b2 vaccine (Pfizer-BioNTech) is associated with a significantly lower rate of SARS-CoV-2, there are still cases of infection among fully vaccinated adults. And after the vaccination rollout, the CDC eliminated the need for quarantine after exposure.

Yonatan Oster, M.D., and a team of Israel-based investigators studied the association between exposure characteristics and infection risk among vaccinated and non-vaccinated healthcare workers in Israel. To do this, they conducted a case-control study between January and March 2021 at the Hadassah-Hebrew University Medical Center. Hospital executives executed the vaccination program and within two months, it achieved almost complete vaccination coverage and a significant decrease in the number of infected healthcare workers.

The investigators compared all vaccinated healthcare workers who tested positive at least two weeks after getting the second dose. Workers were placed into two control groups — all non-vaccinated workers who had positive test results during the same period and a sample of vaccinated workers who were tested but had negative results. The team collected data including demographic characteristics, symptoms, characteristics of exposure, and disease course.

There were 5,312 vaccinated healthcare workers and 690 non-vaccinated healthcare workers at the end of the study period. Of those vaccinated, .5% had positive test results for COVID-19 and 10% of non-vaccinated healthcare workers had positive test results for the virus.

Among the positive groups, symptoms were the common cause for testing (62% in the non-vaccinated-positive group and 63% in the vaccinate-positive group), but not in the vaccinated-negative group (22%).

Being exposed to a positive household member was significantly more common for healthcare workers in the vaccinated-positive group (56%) compared to the non-vaccinated-positive group (38%) and the vaccinated-negative group (9%). When it came to the odds ratio of exposure to positive household members, vaccinated-positive healthcare workers had an OR of 2.03 compared to non-vaccinated-positive healthcare workers and an OR of 12.5 compared with vaccinated-negative healthcare workers.

The research letter, “Association Between Exposure Characteristics and the Risk for COVID-19 Infection Among Health Care Workers With and Without BN-T162b2 Vaccination,” was published online in JAMA Network Open.