Reactogenicity following two doses of the BNT162b2 mRNA COVID-19 vaccine: Real-world evidence from healthcare workers in Japan

As the first authorized COVID-19 vaccine in Japan, the BNT162b2 mRNA COVID-19 vaccine is utilized for mass vaccination. Although efficacy has been proved, real-world evidence on reactogenicity in Japanese personnel is needed to prepare the public. Healthcare workers in a large academic hospital in Japan received two doses of the Pfizer-BioNTech vaccine from March 17 to May 19, 2021. Online questionnaires were distributed to registered recipients following each dose, from day 0 through day 8. Primary outcomes are the frequency of reactogenicity including local and systemic reactions. Length of absence from work was also analyzed. Most recipients self-reported reactogenicity after the first dose (97.3%; n = 3254; mean age [36.4]) and after the second dose (97.2%; n = 3165; mean age [36.5]). Systemic reactions following the second dose were substantially higher than the first dose, especially for fever (OR, 27.38; 95% CI, [22.00-34.06]; p < 0.001), chills (OR, 16.49; 95% CI, [13.53-20.11]; p < 0.001), joint pain (OR, 8.49; 95% CI, [7.21-9.99]; p < 0.001), fatigue (OR, 7.18; 95% CI, [6.43-8.02]; p < 0.001) and headache (OR, 5.43; 95% CI, [4.80-6.14]; p < 0.001). Reactogenicity was more commonly seen in young, female groups. 19.3% of participants took days off from work after the second dose (2.2% after the first dose), with 4.7% absent for more than two days. Although most participants reported reactogenicity, severe cases were limited. This study provides real-world evidence for the general population and organizations to prepare for BNT162b2 mRNA COVID-19 vaccination in Japan and other countries in the region.