High temperature, COVID-19, and mortality excess in the 2022 summer: a cohort study on data from Italian surveillances

• Published in: The Science of the total environment 2023-08, Vol.887, p.164104-164104, Article 164104
• Main Authors: Venturelli, Francesco, Mancuso, Pamela, Vicentini, Massimo, Ottone, Marta, Storchi, Cinzia, Roncaglia, Francesca, Bisaccia, Eufemia, Ferrarini, Chiara, Pezzotti, Patrizio, Giorgi Rossi, Paolo
• Format: Article
• Language: English
• Subjects: Cohort Studies; COVID-19; High temperature; Hot Temperature; Humans; Italy; Mortality; Sars-CoV-2; Surveillance; Temperature
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.164104

We aimed to assess whether the effect of high temperature on mortality differed in COVID-19 survivors and naive. We used data from the summer mortality and COVID-19 surveillances. We found 3.8 % excess risk in 2022 summer, compared to 2015–2019, while 20 % in the last fortnight of July, the period with the highest temperature. The increase in mortality rates during the second fortnight of July was higher among naïve compared to COVID-19 survivors. The time series analysis confirmed the association between temperatures and mortality in naïve people, showing an 8 % excess (95%CI 2 to 13) for a one-degree increase of Thom Discomfort Index while in COVID-19 survivors the effect was almost null with −1 % (95%CI −9 to 9). Our results suggest that the high fatality rate of COVID-19 in fragile people has decreased the proportion of susceptible people who can be affected by the extremely high temperature. [Display omitted] •The 2022 summer showed a 4 % excess of mortality, compared to 2015–2019 summers.•The 2022 summer excess was higher in people over 74 and in the hottest period.•COVID-19 survivors showed lower mortality differences by period compared to naïve.•The risk of dying increased with an increase of temperature in naïve people only.•High temperatures point out the harvesting effect of COVID-19 in elderly people.