Factors Associated with Vaccine Breakthrough Incidence among Health Care Workers Vaccinated with Inactivated SARS-CoV2 Vaccine (CoronaVac)

Healthcare workers (HCWs) run a high risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The HCWs are prone to the SARS-CoV-2 infection in the hospital despite being fully vaccinated. The present study aimed to address the factors associated with the coronavirus disease 2019 (COVID-19) vaccine breakthrough among HCWs. Study Design: A prospective cohort study.

Participants were 184 HCWs receiving two doses of inactivated SARS-CoV-2 vaccine (CoronaVac, Sinovac Life Science). All participants were followed for six months. Confirmed COVID-19 was defined as positive SARS-CoV-2 by reverse transcription-polymerase chain reaction (RT-PCR). Before undergoing RT-PCR, questionnaires were used to obtain information on demographic characteristics, profession, contact with COVID-19 cases, personal protective equipment (PPE), health protocols adherence, exercise, and nutritional habits.

A number of 57 (31%) participants were COVID-19 positive. Close contact with COVID-19 cases (adjusted RR 6.82, 95% CI: 1.97, 47.98, P = 0.044), being a resident doctor (adjusted RR 4.72, 95% CI: 1.11, 20.11, P = 0.036), improper mask-wearing (adjusted RR 2.36, 95% CI: 1.15, 4.85, P = 0.019), and lower frequency of eating fruit and vegetables (adjusted RR 2.73, 95% CI: 1.34, 5.57, P = 0.006) increased the risk of vaccine breakthrough. Compared to single surgical masks, KN95 and N95 significantly reduced the risk of COVID-19 (adjusted RR 0.27, 95% CI: 0.07, 0.97, P = 0.045 and adjusted RR 0.25, 95% CI: 0.07, 0.87, P = 0.029), respectively.

As evidenced by the obtained results, being a resident doctor, close contact with confirmed COVID-19 cases, health protocol incompliance, as well as the lower frequency of fruit and vegetable consumption were associated with the risk of vaccine breakthrough among HCWs. Appropriate strategies are needed to prevent the risk of SARS-CoV-2 infection among HCWs.