Author(s)

Victoria Delicado-Useros^1*, Esther Navarro-Rodenas², Indalecio-M Sánchez-Onrubia³, Carmen Ortega-Martínez^4*, Antonia Alfaro-Espín⁴, Juan-D Pérez-Serra⁵, Francisco García-Alcaraz⁴, Julia Lozano-Serra⁶, Lorena Robles-Fonseca⁶, Teresa Pérez-Domenech^2*

¹Nursing Faculty Castilla-La Mancha University, Nursing & Society Research Group, Albacete, Spain.
²Emergency Department, General Hospital, Almansa, Spain.
³Emergency Department, General Hospital, Albacete, Spain.
⁴Nursing Faculty, Nursing & Society Research Group, Universidad de Castilla-La Mancha, Albacete, Spain.
⁵Emergency Department, Son Espasses Universitary Hospital, Palma de Mallorca, Spain.
⁶Departament of Clinical Microbiology in Albacete General Hospital, Albacete, Spain.

Background: The COVID-19 pandemic continues to be a major worldwide health problem. The present study aims to contribute to surveillance of the immune and clinical response of vaccines to SARS-CoV-2. Methods: Observational medication study on acquired immunity and effectiveness of vaccines. Population: 620 workers in the health service of Almansa (Spain). Representative sample of 150 individuals. Sociodemographic, clinical, and epidemiological data and samples were recorded to determine anti-SARS-CoV-2 serum IgG levels 6 and 9 months after vaccination with Pfizer. Results: Mean age 46.45 years; 76% women; 85.1% working in a hospital. 19.3% had had COVID-19 in the year prior to vaccination. 96.7% were fully vaccinated with Pfizer/BioNTech. At 6 months, 100% seropositivity and mean IgG levels of 3017.2 AU/ml. Significant variations in IgG levels in individuals with prior COVID-19 infection and smokers. At 9 months, 99.3% remained seropositive; 2.8% infected after vaccination. The repeated measures analysis showed a difference in means of 669.0 AU/ml (significant decrease in IgG levels of 28.9%). Conclusion: Antibody levels remained positive 6 and 9 months after vaccination, although IgG levels were found to decay.

Acquired Immunity, SARS-CoV-2 Vaccine, IgG level, Healthcare Workers, COVID-19 Incidence Rate

Delicado-Useros, V. , Navarro-Rodenas, E. , Sánchez-Onrubia, I. , Ortega-Martínez, C. , Alfaro-Espín, A. , Pérez-Serra, J. , García-Alcaraz, F. , Lozano-Serra, J. , Robles-Fonseca, L. and Pérez-Domenech, T. (2023) Evolution of Acquired Humoral Immunity after Full Vaccination against SARS-CoV-2. IgG Levels in Healthcare Workers at 6 and 9 Months. World Journal of Vaccines, 13, 13-32. doi: 10.4236/wjv.2023.132002.