Objective: The development of successful COVID-19 vaccines depends on both effectiveness and safety. Vaccine hesitancy is impacted by vaccine side effects. Therefore, this study aimed to evaluate the post-vaccination symptoms and adverse effects in the adult population who had received either one or two doses of the inactivated vaccines Sinopharm and Sinovac.

Methodology: This was a multicenter, cross-sectional study that was conducted in different hospitals, using a random sampling technique. The duration of the study was about six months, from July 2022 to December 2022, after receiving ethical approval. A total of 400 participants, aged 18 to 59 years, of both genders, who were able to give consent, were currently residing in Karachi, and had received at least one dose of the inactivated COVID-19 vaccines, Sinopharm and SinoVac, were included in the study. The frequency of the side effects following the first and second doses of COVID-19 vaccination was expressed in percentages, while demographics were shown as mean and standard deviation.

Results: The study findings showed that out of 400 participants, 262 (65.5%) were male and 138 (34.5%) were female, with a mean age of 41 years. Around 284(71.0%) participants received SinoVacvaccine and 116(29.0%)received Sinopharm, of whom 42(10.5%) received the first dose and 284(71.0%) received both doses of the inactivated vaccine. The most commonly reported side effect after 1^st dose, fever, was reported by 212(53.0%) participants, and out of them, 52(24.5%) reported it to be severe. This was followed by pain, burning and swelling at the site of the injection in decreasing order of frequency. Following the 2^nd dose, fever was reported by 152(38.0%) participants, and in terms of severity, this was the only symptom reported as severe by the most participants.

Conclusion: This study concluded that both Sinopharm and Sinovac are generally safe to administer, and the overall side effects are mild, non-life threatening, and do not require hospital admission. The subjective level of most vaccine recipients was generally satisfactory.

Keywords: COVID-19 vaccines, Sinopharm and Sinovac, side effects, mild, moderate