Acquired Immunity and Effects of SARS-CoV-2 Vaccination in Healthcare Work-ers and Nursing Students. Post-Booster Follow-Up

Abstract

Introduction: Discussions on COVID-19 vaccine efficacy and the duration of immunity are relevant to health policy intervention. Aims: To assess adherence to SARS-CoV-2 vaccination in healthcare workers (HCWs) and nursing students (NS). To determine IgG levels after booster doses and to identify effects of vaccination. Methods: Observational followup study on the impact of COVID-19 and vaccine efficacy in 2021 and 2022. The study population comprised HCWs and NS from Albacete (Spain). The sample size was 179 HCWs and 120 NS. Data was gathered using a self-administered questionnaire and venous blood samples 6 months after full vaccination and 6 months after the booster dose, in which IgG levels against SARS-CoV2 were measured. Univariate statistical analyses and bivariate analyses were performed using SPSS (28.0). The project was ap-proved by the Ethics and Clinical Research Committee of Albacete. Results: A total of 229 individuals completed the questionnaires and participated in the initial analyses (148 HCWs and 81 NSs). Adherence to the SARS-CoV-2 vaccination regimen was high (100% in NS and 97% in HCWs). Booster doses were received by 94% of the sample. Homologous vaccines were received by 29% and het-erologous vaccines by 71%. IgG levels: 6 months after full vaccination, seropositivity was 100% and mean IgG levels were 3,017.2 AU/ml in HCWs and 2,484.62 AU/ml in NS (p<0.001). At 6 months after the booster dose the mean IgG levels were 25,789.34 AU/ml in PS and 17,155.07 AU/ml in NS (p<0.001). Adverse effects of the vaccines were mild and local, with some present in a high proportion of those vaccinated. Conclusions: After vaccination, antibody levels were positive at 6 months and increase considerably after the booster dose, remaining high 6 months later. No serious side effects were reported, but a high incidence of mild effects, both general and local, was observed.