Retrospective Longitudinal Analysis of Deaths and Mortality in the Over 50 Population Due to COVID-19 in Italy

Abstract

Introduction. COVID-19 has spawned the largest global health crisis of our time. However, part of the scientific community doubts the actual estimate of deaths and the effectiveness of the countermeasures adopted. This paper investigates these aspects in Italy.Methods. A retrospective longitudinal analysis from 2015 to 2021 was conducted to estimate monthly and annual excess deaths and mortality due to COVID-19 in the over 50 age group. Differences between 2020 and 2021 were explored to assess the long-term impact of countermeasures. Surprisals were adopted to measure statistical surprise (e.g., “S = 10” is as surprising as 10 consecutive heads). Effect size and statistical surprise were judged separately.Results. COVID-19 led to a large and unexpected increase in annual (March – December) deaths (excess 2020 = 109519, excess 2021 = 56197, SE = 2229, S > 52) and mortality (excess 2020 = 0.42%, excess 2021 = 0.24%, SD = 0.012%, S > 52). The disease caused relative increases in deaths in almost all months (median = 9%, IQR: 7-21, S = 12) but was more severe in the non-summer periods (median = 9%, IQR: 7-12, S = 12). In 2021 there was a drastic reduction in annual mortality (difference = 681%, SE = 4%, S = 18) and monthly deaths during the periods with the higher epidemiological risk (difference = 47114, SE = 1115, S = 19).Discussion and conclusions. In light of the comparison with the complementary literature, these findings strongly support the dangerousness of COVID-19 – the severity of which increases in the colder seasons but does not disappear in the warmer ones – and the effectiveness of the containment and prevention countermeasures adopted in Italy (especially vaccines). Further studies could investigate counterfactual scenarios to search for more optimal public health interventions.