Abstract
Background It is not clear how the influence of host, environment, and agent on disease outcomes has varied throughout the covid-19 pandemic. Objective Assess the differences in the epidemiological triad between cases of covid-19 in unvaccinated (2020) and cases not fully vaccinated (2021). Methodology Comparison of secondary data of cases of covid-19 without vaccination of previous studies in 2020, with cases of covid-19 in not fully vaccinated people in 2021 (proxy of non-vaccinated persons), all of them carried out in the same population of patients treated in a general medicine office in Toledo, Spain (thus avoiding the confounding factor of comparing different places and environments). Results 100 covid-19 cases were included in 2020, and 12 in 2021. Unvaccinated covid-19 cases during 2020 vs. partially vaccinated covid-19 cases (assimilated to unvaccinated) during 2021 did not differ in a statistically significant way, by age, sex, severity of covid-19, or chronic diseases, or presence of socio-health workers. In 2020 vs. 2021, the symptoms of Respiratory, Digestive, Neurological, Psychiatric and Skin predominated, but without statistical significance; and in 2021, General, and ENT symptoms predominated (the latter with statistical significance p= .048019). Conclusion The clinical presentation of covid-19 cases in 2020 was different than in 2021, and this difference does not seem to be due to the characteristics of the hosts or the context (which did not vary in the studies being compared), but to variables dependent on the virus itself.