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Cumulative incidence of SARS-CoV-2 infection in the general population of the Valencian Community (Spain) after the surge of the Omicron BA.1 variant |
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| Authors: | Jorge Camacho Estela Giménez Eliseo Albert Joao Zulaica Beatriz Álvarez-Rodríguez Ignacio Torres Luciana Rusu Javier S Burgos Salvador Peiró Hermelinda Vanaclocha Ramón Limón María Jesús Alcaraz José Sánchez-Payá Javier Díez-Domingo Iñaki Comas Fernando Gonzáles-Candelas Ron Geller David Navarro the Valencian Vaccine Research Program |
| Institution: | 1. Microbiology Service, Clinic University Hospital, INCLIVA Health Research Institute, Valencia, Spain;2. Institute for Integrative Systems Biology (I2SysBio), University of Valencia-CSIC, Valencia, Spain;3. General Directorate of Research and Healthcare Supervision, Department of Health, Valencia Government, Valencia, Spain;4. Foundation for the Promotion of Health and Biomedical Research of the Valencian Community (FISABIO), Valencia, Spain;5. General Directorate of Public Health, Department of Health, Valencia Government, Valencia, Spain;6. General Directorate of Healthcare. Department of Health, Valencian Government, Valencia, Spain;7. Preventive Medicine Service, Alicante General and University Hospital, Alicante, Spain
Alicante Institute of Health and Biomedical Research (ISABIAL), Alicante, Spain;8. Biomedicine Institute of Valencia, Spanish Research Council (CSIC), Valencia, Spain CIBER in Epidemiology and Public Health, Spain;9. Joint Research Unit “Infection and Public Health” FISABIO-University of Valencia, Valencia, Spain |
| Abstract: | Studies investigating the cumulative incidence of and immune status against SARS-CoV-2 infection provide valuable information for shaping public health decision-making. A cross-sectional study on 935 participants, conducted in the Valencian Community (VC), measuring anti-SARS-CoV-2-receptor binding domain-RBD-total antibodies and anti-Nucleocapsid (N)-IgGs via electrochemiluminescence assays. Quantitation of neutralizing antibodies (NtAb) against ancestral and Omicron BA.1 and BA.2 variants and enumeration of SARS-CoV-2-S specific-IFNγ-producing CD4+ and CD8+ T cells was performed in 100 and 137 participants, respectively. The weighted cumulative incidence was 51.9% (95% confidence interval CI]: 48.7–55.1) and was inversely related to age. Anti-RBD total antibodies were detected in 97% of participants; vaccinated and SARS-CoV-2-experienced (VAC-ex; n = 442) presented higher levels (p < 0.001) than vaccinated/naïve (VAC-n; n = 472) and nonvaccinated/experienced (UNVAC-ex; n = 63) subjects. Antibody levels correlated inversely with time elapsed since last vaccine dose in VAC-n (Rho, ?0.52; p < 0.001) but not in VAC-ex (rho ?0.02; p = 0.57). Heterologous booster shots resulted in increased anti-RBD antibody levels compared with homologous schedules in VAC-n, but not in VAC-ex. NtAbs against Omicron BA.1 were detected in 94%, 75%, and 50% of VAC-ex, VAC-n and UNVAC-ex groups, respectively. For Omicron BA.2, the figures were 97%, 84%, and 40%, respectively. SARS-CoV-2-S-reactive IFN-γ T cells were detected in 73%, 75%, and 64% of VAC-ex, VAC-n and UNVAC-ex, respectively. Median frequencies for both T-cell subsets were comparable across groups. In summary, by April 2022, around half of the VC population had been infected with SARS-CoV-2 and, due to extensive vaccination, displayed hybrid immunity. |
| Keywords: | cumulative incidence of SARS-CoV-2 infection neutralizing antibodies SARS-CoV-2 seroprevalence T cells |