SARS-CoV-2 infection rates after different vaccination schemes

Objective: To identify effects of various nationwide vaccination protocols on the evolution of new SARS-CoV-2 infections among adult population and to evaluate the safety of mRNA (BioNTech/ Pfizer) vaccine. Methods: Totally 10 735 adult volunteers that received at least one dose of BioNTech/Pfizer or triple doses of CoronaVac participated in this cross-sectional-online survey between 1 and 10 September 2021. The information was collected covering a 5-month period from April 2021 to September 2021. Information about people who were vaccinated with only single and double dose CoronaVac were not included in this study. Results: At least one side effect after single and double dose of BioNTech/Pfizer and triple doses of CoronaVac were observed in 42.1%, 42.5% and 10.9%, respectively. The most common side effects were shoulder/arm pain, weakness/fatigue, muscle/joint pain and headache. The side effects were the most frequent in single BioNTech/Pfizer, while it was the least in triple CoronaVac. The rate of positive PCR tests before vaccination was 17.6%, and decreased to 3.0% after vaccination. The rates of positive SARS CoV-2-PCR were 18.8%, 3.5%, 3.1%, 0.5% and 4.6% in single BioNTech/Pfizer, double BioNTech/Pfizer, double CoronaVac+single BioNTech/Pfizer, double CoronaVac+double BioNTech/Pfizer and triple CoronaVac, respectively. While 1.8% of PCR positive COVID-19 cases needed intensive unit care in the pre-vaccination period, intensive care unit was required in 0%, 1.5%, 2.4%, 0% and 4.2% after single BioNTech/ Pfizer, double BioNTech/Pfizer, double CoronaVac+single BioNTech/ Pfizer, double CoronaVac+double BioNTech/Pfizer and triple CoronaVac, respectively. Reinfection rate after vaccination was 0.4%. Conclusions: The rarity of COVID-19 infection after vaccination suggests that efficacy of vaccines is maintained. On the other hand, the data underscore the critical importance of continued public health mitigation.