Risk Factors and Incidence Rates of Covid-19 Breakthrough Infections in Vaccinated People in General Medicine Practice in Toledo (Spain)

Background: COVID-19 vaccines show excellent efficacy, but some people still become infected after vaccination. Objective: To determining incidence rates (IR) and risk factors of COVID-19 breakthrough infections in vaccinated people. Methodology: A longitudinal and prospective case-control study of COVID-19 breakthrough infections in vaccinated people was carried out from February 1, 2021 to September 30, 2021, in a general practitioner (GP) office in Toledo (Spain). Results: IR of COVID-19 breakthrough infections in vaccinated people > 14 years in GP consultation was 1.5% cases × 8 months; higher in people > = 65 years vs. 14-65 years (2.3% vs. 1.3%), and higher in women vs. men (1.6% vs. 1.4%). IR according to the type of vaccine ranged from 0.4% cases with mRNA-1273 vaccine, to 5% cases with Janssen vaccine. The statistically significant protective factors were: complex family and chronic illnesses of the mental group; and statistically significant risk factors: chronic diseases of the digestive and musculoskeletal groups. Vaccination with BNT162-2 mRNA and mRNA-1273 were protective factors; and with ChAdOx1 nCoV-19 shown a moderate risk. Vaccination with Janssen was a statistically significant strong risk. Conclusion: COVID-19 breakthrough infections in vaccinated people were rare, with higher rates in women and old people. Chronic diseases and social factors behaved mixed. Each of the vaccines has associated COVID-19 breakthrough infections, but the Janssen vaccine posed a strong risk; however, the small numbers prevent definitive conclusions.