Abstract
OBJECTIVES: To assess the immunity of healthcare and non-healthcare workers in the Alcoy health area (Spain) after completing three doses of the Pfizer-BioNTech vaccine and how it relates with individual factors. METHODS: We conducted a prospective, observational, longitudinal, analytical study to observe immunogenicity in healthcare and non-healthcare workers at Virgen de los Lirios Hospital following administration of three doses of the Pfizer-BioNTech vaccine. Anti-SARS-CoV-2 spike protein IgG antibody concentrations were determined, while COVID-19 infections were identified by qualitative detection of IgG against the nucleocapsid protein. Samples from volunteers were analyzed 15 days, 3 months, and 6 months after receiving the second vaccine dose, and 12 months after receiving the third (booster) dose. A questionnaire was used to collect demographic data, risk factors, and use of immunosuppressive drugs. Statistical analyses were performed with SPSS software, and mean antibody levels over time were compared using ANOVA. RESULTS: Participation was 99.5 % (199/200). The IgG concentration was higher in men and in obese individuals. No significant changes were noted in factors such as smoking. CONCLUSIONS: All participants developed humoral immunity, except for three subjects who were receiving immunosuppressive treatment. Participants with previous COVID-19 infection had higher antibody levels.