Adverse event following immunisation of adsorbed-inactivated Coronavac (Sinovac) and ChAdOx1 nCOV-19 (Astra Zeneca) of COVID-19 vaccines.

Introduction: Countries around the world organised mass vaccinations using various types of vaccines against COVID-19, like inactivated viruses and mRNA. The study aimed to look at adverse events following immunisation (AEFI) of Coronavac® (SIN) and ChAdOx1 nCOV-19 ® (AZ) COVID-19 vaccines in Indonesia.

Materials and methods: Subjects who received SIN or AZ vaccines were sent questionnaires twice: after they received the first and the second doses of vaccine, respectively. AEFI data on the first- and second-day post-vaccination were collected and analyzed descriptively.

Results: A total of 1547 people vaccinated with SIN vaccine, 529 (33.3%) responded to the first-dose and 239 (47%) to the second-dose questionnaires, whereas 936 people vaccinated with AZ vaccine, 483 (51.6%) answered the firstdose and 123 (25%) to the second-dose questionnaires. Some important AEFIs on the first- and second-day post receiving SIN vs. AZ vaccination were as follows: fever 4% vs 59%; pain at the injection site 27% vs 87%; redness and swelling at the injection site 4% vs 18%; nausea 5% vs 30%; diarrhea 1.8% vs 5.7%, respectively.

Conclusion: SIN seemed to have fewer AEFIs than AZ. Apart from different vaccine materials and excipients, the gap in AEFIs between SIN and AZ could be caused by the distinct population where AZ recipients were more exposed to COVID-19.