Aguilera, XimenaGonzález, ClaudiaApablaza, MauricioRubilar, PaolaIcaza, GloriaRamírez-Santana, MurielPérez, ClaudiaCortés, Lina JimenaNúñez-Franz, LoretoQuezada-Gaete, RubénCastillo-Laborde, CarlaCorrea, JuanSaid, MacarenaHormazábal, JuanVial, CeciliaVial, Pablo2023-04-272023-04-272022Aguilera, X., González, C., Apablaza, M., Rubilar, P., Icaza, G., Ramírez-Santana, M., ... & Vial, P. (2022). Immunization and SARS-CoV-2 antibody seroprevalence in a country with high vaccination coverage: Lessons from Chile. Vaccines, 10(7), 1002https://repositorio.udd.cl/handle/11447/7417Objective: Chile is among the most successful nations worldwide in COVID-19 vaccine rollout. By December 31st, 2021, 84.1% of the population was fully vaccinated, and 56.1% received booster doses using DIFFERENT TYPES OF COVID-19 VACCINES. In this context, we aimed to estimate the anti-SARSCoV-2 antibodies following the infection and vaccination campaign. Study design: Population-based cross-sectional serosurvey based on a representative sample of the cities of Santiago, Coquimbo/La Serena, and Talca used in a previous study. Methods: We selected the participants using a three-stage stratified sampling. They were blood-sampled on-site and answered a questionnaire regarding COVID-19-associated variables and vaccination antecedents using Wantai SARS-CoV-2 Ab ELISA to determine seroprevalence. This research followed the generic protocol of World Health Organization Unity studies. Results: We recruited 2,198 individuals aged 7-93 between October 5th and November 25th, 2021. In our sample, 2,132 individuals received COVID-19 vaccinations (97%); 67 (3.1%) received one dose; 2,065 (93.9%) received the complete scheme; and 936 received the booster jab (42.6%). Antibody seroprevalence reached 97.3%, ranging from 40.9% among those not vaccinated to 99.8% in those with booster doses (OR=674.6, 154.8-2938.5). SARS-CoV-2 antibodies were associated with vaccination, previous COVID-19 diagnosis, age group, and city of residence. In contrast, we found no significant differences in the type of vaccine used, education, nationality, or type of health insurance. Conclusion: We found a seroprevalence close to 100% in the population aged seven years and older, primarily due to the successful vaccination program, which has a strong emphasis on universal access.11 p.enCOVID-19, Vaccine coverage, Sinovac CoronaVac, BNT162b2, AZD1222, Ad5-nCoV, cross sectional, population-based, Santiago, Talca, Coquimbo, La Serena, ELISA, sero-surveyVaccine coverageSinovac CoronaVacBNT162b2AZD1222Ad5-nCoVCross sectionalPopulation-basedELISASero-surveySantiagoTalcaCoquimboLa SerenaArticlehttps://doi.org/10.21203/rs.3.rs-1548211/v2