COVID-19 vaccination: Does knowledge of higher immunity influence first and second COVID-19 booster uptake? A study carried out in a university population.

[en] BACKGROUND: Knowledge of prior immunity may influence individuals' decisions about continuing their vaccination schedule. Based on a previous study, we hypothesise that participants who believe they have higher immunity due to knowledge of previous infection(s) or a higher level of neutralising antibodies will be less likely to get a boost, namely a first and a second COVID-19 booster vaccine.
METHODS: This research is part of a longitudinal study carried out among students and staff of the University of Liège (ULiège), Belgium, between April 2021 and December 2022, whose objectives included studying vaccine hesitancy to COVID-19. For the analyses, two dependent variables were considered: the first and the second COVID-19 booster vaccine (yes/no). Binary logistic regressions were performed to explore the relationship between these variables and sociodemographic characteristics, health literacy, past COVID-19 vaccination intentions, knowledge of SARS-CoV-2 infection and anti SARS-CoV-2 neutralizing antibody levels.
RESULTS: The sample included 822 participants. Globally, 88.8% of participants received the first booster vaccine compared to 21.8% for the second booster vaccine. Lower past COVID-19 vaccine intention, knowledge of previous SARS-CoV-2 infection and higher neutralizing antibody levels were associated with a lower first COVID-19 booster uptake. Lower age, lower past COVID-19 vaccine intention and knowledge of higher neutralizing antibody levels were associated with a lower second COVID-19 booster uptake.
CONCLUSIONS: The results show that COVID-19 vaccination decreases with time. Our initial hypothesis is partially confirmed, with an influence of knowledge of previous SARS-CoV-2 infection and neutralizing antibodies on the first booster vaccine uptake and an influence of knowledge of neutralizing antibodies on the second booster vaccine. A long-term, personalized and transparent educational approach, centred on knowledge of prior immunity for the individual and current scientific knowledge/uncertainties about vaccine and infection-related protection, appears to be necessary to enable individuals to make a more informed decision about vaccination.