Common adverse events following immunization with moderna Covid-19 vaccine among Vietnamese adults at Hanoi Medical University in 2021

The rapid creation of vaccinations has increased the risk of vaccine safety. In less than two years, a significant number of COVID-19 vaccines were developed and approved in various countries to control the COVID-19 pandemic. This study was conducted to identify the common adverse events following immunization with mRNA-1273 (Moderna COVID-19) vaccine among adults in 2021. A cross-sectional study using randomized sampling was conducted in Hanoi, Vietnam, with 766 participants. The results show that the prevalence of AEFIs after the 1st dose was significantly lower than after the 2nd dose (41.25% vs. 85.64%, p < 0.05). Local effects, fever, fatigue, and increased pain sensation were the most common side effects encountered in both 1st and 2nd dose. The AEFIs are mostly mild and automatically wore off after one to three days. Therefore, the Moderna COVID-19 vaccine is safe for injection.