COVID-19 infection after vaccination.

Background: Although vaccination is the most effective and specific approach for prevention of infectious diseases, but in a small percentage of vaccinated person's breakthrough infections can occur. This study aimed to determine the effectiveness of different common coronavirus vaccines in this area.

Methods: 109 COVID-19 vaccinated patients were enrolled, with different types of vaccines (Sinopharm, AstraZeneca, Sputnic, Bharath, CovIran Barkat and Pasto-CoV) and time of administration in 2021 in Babol, Iran. Patients after 14 days of administration of the final dose of corona vaccines with positive COVID-19 RT-PCR test entered to study. Patients' data such as RT-PCR, type of vaccine, age, sex and outcome were collected using electronic medical records.

Results: 47 patients were not fully vaccinated, 62 had two vaccine doses and 51 were fully vaccinated and considered to a breakthrough infection. Although, most of the patients with SARS-CoV-2 infection were either mild (n=18 [16.56%]), or moderate (n=86 [78.9%]), 5 (4.6%) patients had severe or critical illness, of whom 3 admitted in intensive care unit, 3 intubated, and 4 died. The average age of the participants with COVID-19 infections was 61.23 ± 19.91 years.

Conclusion: Based on our results, the COVID-19 breakthrough occurring with two doses of current vaccines were mild and moderate.