COVID-19 vaccination campaigns and health outcomes in Spain during 2021

We evaluate the effects of vaccines in the evolution of the epidemic in Spain during 2021. To this end, we estimate the effect of vaccination in terms of reducing infections, hospitalizations, ICU admissions, and deaths. We also compare the health impact of COVID-19 with that caused by recent influenza seasons, in a scenario where all the population had been vaccinated. The positive impact of vaccination on health indicators has been extraordinary. The non-availability of vaccines would have increased COVID-19 deaths by 571% compared to observed deaths. Moreover, the relative benefit of vaccination increases with the severity of the indicator: greater for deaths and ICU admissions, less for infections and hospitalizations. Under the assumption that the entire population had been vaccinated with the COVID-19 vaccine from the first week of April, the impact of the disease in terms of hospitalizations and deaths during 2021 would have been above a low activity flu season, but in line with a moderate/high activity flu season.