Breakthrough COVID-19 infections and perceived vaccine effectiveness

While SARS-CoV-2 vaccines provide significant protection against severe COVID-19 illness, breakthrough infections have sparked confusion among patients about the effectiveness of vaccination. It's unclear if (or to what extent) breakthrough infection experiences impact public perceptions of COVID-vaccine effectiveness, though the answer may have significant implications for public health communications and ongoing vaccine acceptance.

We conducted a survey of 2,500 adults in the United States (February 27 - March 9, 2023) in order to better understand the relationship between breakthrough COVID-19 infections and perceived vaccine effectiveness. Survey respondents were selected using a stratified, quota sampling approach to ensure representativeness; analysis was conducted on responses from 1,928 participants who received a COVID-19 vaccine.

Among those who tested positive for COVID-19 after being vaccinated, 21.18 % said that COVID-19 vaccines had been "less effective" than they initially expected, compared with 10.0 % of those who did not experience any breakthrough infections (X² = 75.551; φ = 0.198; p ≤ 0.001). Those who experienced their own breakthrough infection were 1.37 times less likely to report perceived vaccine efficacy, while those whose family members experienced a breakthrough infection were 1.64 times less likely to report the same, ceteris paribus. The largest effect was observed among those who experienced both a personal and familial breakthrough infection. This group was almost two times less likely to describe COVID-19 vaccines as "very effective".

Breakthrough infections correlated with lower overall levels of perceived vaccine effectiveness, even after accounting for demographic and political considerations. Moving forward, public officials and health professionals should work proactively to ensure that breakthrough infections are understood in the broader context of overall vaccine effectiveness.