Objective: Effectiveness and safety are essential for the progression of effective COVID-19 vaccines. The side effects of vaccines affect vaccine reluctance. Therefore, this study aimed to determine the prevalence, and onset of side effects following the first and second doses of COVID- 19 vaccines among hypertensive and non-hypertensive individuals.

Methodology: This was a multicenter, cross-sectional study that was conducted in different hospitals, using a non-probability sampling technique. The duration of the study was about six months, from August 1, 2022, to January 31, 2023.A total of 818 participants were divided into two groups: hypertensive (n=414) and normotensive or non-hypertensive (n=404) who received one of COVID-19 vaccines, such as Sinopharm, Sinovac, Astrazeneca, and Pfizer. The frequency of side effects was evaluated among hypertensive and non-hypertensive participants using the Chi-square test. An independent t-test was used to compare the association between means.

Results:The study findings showed that themean age of hypertensive participants was 47.7±14.0 years while the mean age of non-hypertensive participants was 39.04±14.6 years. Most participants received Sinovac,by 186(45.1%) hypertensive participants and 150(37.1%) non-hypertensive participants.Following the first dose, the risk of side effects was higher in hypertensive participants. Pain at the injection site was experienced by 251(60.6%) hypertensive and 170(42.1%) non-hypertensive participants, with a significant difference observed among them, (p<0.001). Moreover, following the second dose, redness at injection site, lymphadenopathy, headache, nausea, flu, anxiety, fatigue, swelling of glands, shortness of breath, and chest pain were significantly associated with both groups (p<0.001).

Conclusion: This study concluded that hypertension is a common comorbidity in COVID-19 individuals and is linked with greater reported side effects after vaccination in participants with hypertensio. Fever, discomfort, and burning at the injection site were the most frequent side effects after the first dose, and were more pronounced in participants with hypertension. Additionally, pain at the injection site, rashes, and fever were the most common side effects after the second dose.

Keywords: COVID-19 vaccines, hypertension, side effects, pain, fever