[Effect of the Omicron variant on cumulative incidence of infection and lethality during the sixth wave of the COVID-19 epidemic in Spain]. / Efecto de la variante Ómicron sobre la incidencia y la letalidad durante la 6.ª onda epidémica COVID-19 en España.

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 Ómicron variant (10.89% vs 0.75% with Delta) while the CFR was higher with the Delta variant (4.2‰ vs 1.3‰ with Ómicron), as well as a higher rate of hospitalization and ICU admission with the Delta variant.