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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

The Role of Vitamin D for Modulating the T Helper 1 Immune Response After the Coronavac Vaccination.

The purpose of this study was to observe the role of vitamin D levels with T helper 1 (Th1)-type cytokines, such as interferon γ (IFN-γ) and interleukin-12 (IL-12) efficacy, in those who had already received 2 injections of inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) vaccines (CoronaVac). We also observed if these cytokines played any significance in the CoronaVac effectiveness for preventing coronavirus disease 2019 (Covid-19) infection. One hundred ninety-four volunteers were monitored for 8 months upon receiving 2 inactivated SARS-CoV2 vaccination injections (CoronaVac, Sinovac Life Sciences). The rate of confirmed Covid-19 infections was the primary outcome. Six to 7 weeks after the second vaccine injection, and blood samples were obtained to measure the serum vitamin D, IFN-γ, and IL-12 levels. Low vitamin D level was defined if vitamin D level <30 ng/mL. Subjects with low vitamin D had lower IFN-γ and IL-12 levels (P = 0.04 and P = 0.04, respectively). The receiver operating characteristics curve analysis revealed that the area under curve for IFN-γ was 0.59, whereas IL-12 was 0.59 for predicting the low vitamin D levels. During follow-up, a higher incidence of Covid-19 infections was observed in subjects with low IFN-γ levels (P = 0.03). Kaplan-Meier survival analysis revealed that the cumulative hazard of confirmed Covid-19 cases was increased in subjects with low IFN-γ levels (log-rank test, P = 0.03). We concluded that lower vitamin D level was correlated with a lower Th1 immune response, whereas the adequate IFN-γ level was required to obtain better CoronaVac effectiveness.