Rates, types, and associated factors of acute adverse effects after the first dose of ChAdOx1 nCoV-19 vaccine administration in Thailand.

OBJECTIVES

Effective vaccines are prioritized to curtail the transmission and burden of coronavirus disease 2019. Nevertheless, monitoring the safety of vaccines is crucial. As Thailand began the ChAdOx1 nCoV-19 vaccination, our study examined the acute adverse effects and associated factors after the first dose of vaccination.

METHODS

A mobile self-report questionnaire was employed to assess the rates and types of different side-effects within 3 days of the first dose of ChAdOx1 nCoV-19 vaccine administration. The risk factors associated with these side-effects were analyzed.

RESULTS

In total, 774 participants were included in the survey, with a mean (± standard deviation) age of 49.5 (± 17.2) years. The majority (57.8%) were females, and 59.1% were anxious before the vaccination. Side-effects after the vaccination were a common occurrence (65.2%), but most (42.6%) were mild. Side-effects were significantly associated (odds ratio [95% confidence interval]) with younger age (4.32 [2.26-8.23]; < 0.001; age < 30 years vs ≥ 60 years), female sex (1.66 [1.19-2.30],  = 0.003), anxiousness (2.10 [1.06-4.13];  = 0.033; moderate-severe anxiousness vs none), and allergic disease (2.60 [1.07-6.31];  = 0.035).

CONCLUSIONS

After the ChAdOx1 nCoV-19 vaccination, most acute adverse effects were mild and often noted among participants with younger age, female sex, anxiousness, and allergic disease.