Acute Adverse Events at a Mass Vaccination Site after the Third and Fourth COVID-19 Vaccinations in Japan

Abstract

The third and fourth doses of the vaccine against coronavirus disease 2019 (COVID-19) were widely administered in Japan since December 2021. Currently, however, data is scarce regarding acute adverse events with the third and fourth doses. The present study reports the profiles of acute adverse events after the third and fourth COVID-19 vaccine doses, seen at the site of a mass vaccination center in Japan. Between December 2021 and July 2022, 267,515 individuals received the third, and 32,934 received the fourth, COVID-19 vaccine dose at the mass vaccination center, of whom 442 recipients of the third (0.19%), and 22 recipients of the fourth (0.07%), dose reported acute adverse events and were examined by doctors on site. The most common diagnosis was vasovagal syncope/presyncope (incidence: 0.01-0.10%), followed by other miscellaneous complaints, acute allergic reactions (0.05-0.005%), and anaphylaxis (< 0.005%). Vasovagal syncope/presyncope occurred most frequently in recipients in those in their 20s, whereas acute allergic reactions were most frequent in those in their 40s. Both reactions were more frequent in women than men. The peak occurrence of vasovagal syncope/presyncope was earlier than 15 min after the injection, whereas that of acute allergic reaction was later than 15 min after the injection. The incidence of acute allergic reactions appeared to differ between various vaccine manufacturers, whereas that of vasovagal syncope/presyncope did not. These real-world data may benefit the safe and efficient implementation of mass vaccination campaigns for citizens who want to receive COVID-19 vaccines now and in the future.

Efficacy of the Second COVID-19 Vaccine Booster Dose in the Elderly

“…The safety profile of the fourth dose also seems reassuring. Akaishi et al [ 21 ] compared the burden of acute side-effects recorded after receiving four doses of mRNA-based COVID-19 vaccines, and reported that the incidence rates after the third and fourth doses were significantly lower than those seen after the first and second administrations. The authors also found that the risk of developing vasovagal syncope/presyncope was lower after the fourth compared to the third vaccine dose (0.02 vs. 0.09%: p < 0.001), as was the likelihood of developing post-vaccine allergic reactions (0.01 vs. 0.03%; p = 0.010).…”

Before and After: Attitude and Adverse Effects Induced by the First and Second Doses of mRNA BNT162b2 Vaccine among Healthcare Professionals in the First Weeks after Their Introduction in Poland

“…Allergic reactions were not common in our study (1% after 1st dose; 0% after 2nd dose), and no incidence of anaphylaxis was reported. In the study by Akaishi et al, acute allergic reactions (0.05–0.005%) and anaphylaxis (<0.005%) were also not common after the 3rd and 4th doses of the vaccine [ 15 ]. It provides valuable information that acute allergic reactions are a relatively uncommon adverse event after SARS-CoV-2 vaccination, which is confirmed by other studies as well [ 16 , 17 , 18 ].…”

Postural orthostatic tachycardia syndrome and other related dysautonomic disorders after SARS-CoV-2 infection and after COVID-19 messenger RNA vaccination

“…In a cohort of 267,515 individuals who received the third and 32,934 individuals who received the fourth COVID-19 vaccine dosage at the vaccination center in Japan, 0.01–0.1% present vasovagal syncope/presyncope ( 126 ). On the other hand, the relationship between long COVID-19 and vaccines remains unclear.…”