Short-term SARS-CoV-2 Re-infection Rate in Vaccinated Health Workers based on Received Vaccines: A Cross-sectional Study

Background Vaccines during the Coronavirus disease 2019 (COVID-19) pandemic entered the market faster than a routine proportionate evaluation cycle. The highest number of deaths and morbidities, especially by the type of B.1.617.2 (Delta) variant, is one of the reasons for this inevitability. Accordingly, evaluation of the effects of vaccines is of great importance.Methods In this cross-sectional study, we investigated the effects of four current COVID-19 vaccines, such as AstraZeneca, Sputnik, Sinopharm, and Bharat, and the prevalence of COVID-19 occurrence among 600 vaccinated healthcare workers (HCWs) in the Southeast of Iran.Results The incidence of infection among vaccinated HCWs was 36.3%, without any age and gender difference, statistically. The infection rate with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) following immunization with AstraZeneca, Sputnik V, Bharat, and Sinopharm vaccines were 45.8%, 41.3%, 36.9%, and 18.6%, respectively (P.V=0.001). Those who had a history of previous SARS-CoV-2 infection were more affected again despite vaccination (P.V=0.001). However, out of 218 infected patients, only six patients (2.8%) were hospitalized, while 26 patients (11.9%) received remdesivir and two patients (0.9%) needed to additional target therapy with Iinterleukin-6 inhibitor of Tocilizumab due to cytokine storm.Conclusion During B.1.617.2 circulating variant, all vaccines after a complete vaccination schedule were relatively associated with protection against severe infection and hospitalization. We found that people who received the Sinopharm vaccine had the lowest incidence of COVID-19 (18.7%), followed by Bharat. The lowest incidence of protection occurred with viral vector-based vaccines, especially AstraZeneca.