Do Side Effects to the Primary COVID-19 Vaccine Reduce Intentions for a COVID-19 Vaccine Booster?

Background: Vaccines are being administered worldwide to combat the COVID-19 pandemic. Vaccine boosters are essential for maintaining immunity and protecting against virus variants. The side effects of the primary COVID-19 vaccine (e.g., headache, nausea), however, could reduce intentions to repeat the vaccination experience, thereby hindering global inoculation efforts.

Purpose: The aim of this research was to test whether side effects of a primary COVID-19 vaccine relate to reduced intentions to receive a COVID-19 booster. The secondary aim was to test whether psychological and demographic factors predict booster intentions.

Methods: Secondary data analyses were conducted on a U.S. national sample of 551 individuals recruited through the online platform Prolific. Key measures in the dataset were side effects reported from a primary COVID-19 vaccination and subsequent intentions to receive a booster vaccine. Psychological and demographic variables that predicted primary vaccination intentions in prior studies were also measured.

Results: Booster intentions were high. COVID-19 booster vaccine intentions were uncorrelated with the number of side effects, intensity of side effects, or occurrence of an intense side effect from the primary COVID-19 vaccine. Correlational and regression analyses indicated intentions for a booster vaccination increased with positive vaccination attitudes, trust in vaccine development, worry about the COVID-19 pandemic, low concern over vaccine side effects, and democratic political party affiliation.

Conclusions: Side effects of a primary COVID-19 vaccine were not directly associated with lower intentions to receive a booster of the COVID-19 vaccine early in the pandemic. However, many variables that predict primary vaccination intentions also predict booster intentions.