Effect of the Omicron variant on cumulative incidence of infection and lethality during the sixth wave of the COVID-19 epidemic in Spain

The COVID-19 pandemic has strained healthcare systems globally. The successive epidemic waves have shown different characteristics. The Omicron variant of SARS-CoV-2 modified the epidemic behavior that previous variants had followed. The aim of this analysis was to determine the epidemiological characteristics of COVID-19 during the sixth epidemic wave and its differences according to the predominance of the Delta or Omicron variants. The epidemiological data corresponding to the sixth wave of the epidemic published by official organizations were analyzed, and the cumulative incidence of infection (CI-I) and case fatality rates (CFR) were calculated, both for Spain as a whole and for the different Autonomous Communities, in the population as a whole and by age groups. The results showed that the CI-I was higher with the & Oacute; micron variant (10.89% vs 0.75% with Delta) while the CFR was higher with the Delta variant (4.2 parts per thousand vs 1.3 parts per thousand with & Oacute; micron), as well as a higher rate of hospitalization and ICU admission with the Delta variant. (c) 2023 Sociedad Espanola de Medicos de Atencion Primaria (SEMERGEN). Published by Elsevier Espana, S.L.U. All rights reserved.

Automated summary

The COVID-19 pandemic has strained healthcare systems globally, and the Omicron variant has modified the epidemic behavior of previous variants. The study found that the cumulative incidence of infection was higher with the Omicron variant, while the case fatality rate was higher with the Delta variant. The Delta variant also had higher rates of hospitalization and ICU admission.