Prevalence and predictors for high blood pressure during covid-19 vaccination in Thailand
Authors: Patamatamkul S 
Published: February 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
The Thai government mandates BP measurement prior to COVID-19 vaccination to ensure safety for all vaccinees. However, there is neither large study regarding the prevalence of high BP nor CV complication during COVID-19 vaccination.

Purpose
To describe the prevalence of high BP defined as SBP≥140 or DBP≥90 mmHg, predictors for high BP and outcome during vaccination day.

Methods
We enrolled all vaccinees at a Thai hospital, during June 2021. We reviewed medical records and compared vaccination day BP with BP from prior 2 visits extracted from the computer database. We used a fully automated non-invasive sphygmomanometers. Diagnosis of hypertension were extracted from the past records using ICD-10 code (I1-). Grade of hypertension were defined according to the ESC guideline 2018. Prior well-controlled BP was defined as SBP &lt; 130 and DBP &lt; 80 mmHg in the 2nd prior visit.

Results
There were 2308 vaccinees during the period and 2307 with complete data for analysis. Female accounted for 57%. The mean age was 49.69 ± 17.44 years old. Body mass index were 25.77 ± 14.10 kg/m2. Prime COVID-19 vaccines shot accounted for 73.6%. All vaccinees were pre-assigned to receive either ChAdOx1 nCoV-19 or CoronaVac: 54.2% and 45.8%, respectively. Essential hypertension was previously diagnosed in 21.5%, and 0.3% for secondary hypertension. The vaccination day mean SBP and DBP were 135.23 ± 17.97 and 76.14 ± 12.06 mmHg. There were 56%, 33%, 10.3% and 0.4% classified as normotension, gradeI, II and III hypertension, respectively. Estimated prevalence for any hypertension and grade II or III hypertension were 44% (95% CI 41.9-46.0) and 11% (95% CI 9.7-12.3), respectively. There were 1,335 participants with at least 2 previous BP measurements prior to the vaccination day. We compared BP change between group of 142 vaccinees who had grade II or III hypertension and group of 1193 vaccinees with normotension or grade I hypertension at vaccination day. There was a significant increase in SBP and DBP at vaccination day in both groups, and significantly higher BP from prior visits in grade II or III hypertension group (Figure 1). After adjusting for age, gender, type of vaccine, dose, previous diagnosis of hypertension and prior well-controlled BP, we found that the previous diagnosis of hypertension and prior well-controlled BP were independent predictors for grade II or III hypertension at vaccination day: OR 2.93 (95% CI 1.97 – 4.36) and 0.47 (95% CI 0.23 – 0.96), respectively. There were 3.38% who required on-site medical attention due to high BP, resulting in a delay to vaccination of 1 hour (IQR, 0.5- 2). Vaccination was postponed in 0.56%. All were diagnosed with hypertensive urgency by the onsite physicians.

Conclusions
Prevalence of high BP was relatively high among Thai vaccinees but without CV event at vaccination day. BP measurement may be unnecessary in asymptomatic vaccinees with previously well-controlled BP. Abstract Figure. SBP change between two groups Abstract Figure. DBP change between two groups