Most Adverse Reactions to 2-Dose Vaccines Are Mild Symptoms Like Injection Site Pain and Fatigue

[Asia Economy Reporter Seonjin Byun] Most adverse events related to the bivalent vaccines used for winter vaccinations were found to be mild symptoms such as injection site pain and fatigue.

[Image source=Yonhap News]

According to the active surveillance results for each bivalent vaccine after additional winter vaccinations announced by the COVID-19 Vaccination Response Promotion Team (Promotion Team) on the 11th, the most frequently reported symptoms among 10,000 monitored individuals were injection site pain, muscle pain, and fatigue, which were similar across all bivalent vaccines.

Active surveillance is conducted to monitor for any unusual cases following bivalent vaccine administration and to ensure the safe use of vaccines. It was carried out by surveying participants who consented, via text messages for one week after vaccination, to check for the occurrence of adverse events, types and duration of symptoms, and whether medical institution visits were made.

The bivalent vaccines currently used for winter vaccinations include four types: Pfizer's BA.1, BA.4/5, and Moderna's BA.1, BA.4/5. The top five symptoms reported were injection site pain, muscle pain, fatigue, headache, and fever/chills.

Additionally, the number of reports by day showed that all bivalent vaccines had the highest number of reports on the first day after vaccination. From the second day onward, the number of reports gradually decreased, with the lowest number reported on the seventh day. Careful attention was required for at least three days after vaccination.

The Promotion Team also announced the results of active surveillance conducted on 545 individuals aged 12 to 17 who received the bivalent vaccine. This was compared and analyzed with the active surveillance results of 3,523 individuals aged 12 to 17 who received the third dose in March last year.

The most frequently reported symptoms among both third-dose recipients and bivalent vaccine recipients were injection site pain, headache, fatigue, muscle pain, and fever/chills, in that order. The reporting rates for most symptoms were found to be lower in the bivalent vaccine group.

In particular, the proportion of those reporting chest pain after vaccination was significantly lower in the bivalent vaccine group (1.7%) compared to the third-dose group (5.6%), approximately one-third the level.