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

We aimed to assess differences in the summer excess of mortality by COVID-19 history using data from the mortality and COVID-19 surveillances. We found 4% excess risk in 2022 summer, compared to 2015-2019. A mortality rate ratio of 1.59 (95%CI 1.39-1.82) for COVID-19 survivors compared to naïve, was found. Both were higher in people aged ≥75 years. During the July heat wave, the excess for COVID-19 survivors decreased and disappeared when excluding people living in nursing homes. Funding statement This study was partially supported by the Italian Ministry of Health –CCM 2020 - “Sorveglianza epidemiologica e controllo del COVID-19 in aree urbane metropolitane e per il contenimento della circolazione del Sars-CoV-2 nella popolazione immigrata in Italia” and by the Ricerca Corrente 2023 Highlights ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was partially supported by the Italian Ministry of Health CCM 2020 Sorveglianza epidemiologica e controllo del COVID-19 in aree urbane metropolitane e per il contenimento della circolazione del Sars-CoV-2 nella popolazione immigrata in Italia and by the Ricerca Corrente 2023. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The collection of data used for this manuscript is compulsory in Italy according to national laws on infectious diseases and summer mortality surveillance. The COVID-19 Italian National Working group on Bioethics has stated that consensus for the collection of this data in the context of the COVID-19 emergency is not mandatory (Rapporto ISS COVID-19 n. 34/2020), based on Guideline 12 of the WHO on ethical issues in public health surveillance. The legal ordinance n. 640 of February 28 2020, explicitly declares Istituto Superiore di Sanita as entitled to collect data for COVID-19 surveillance and contact tracing and that such data can be used and shared, upon anonymization, to advance scientific knowledge on this new disease. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes According to Italian law, anonymized data can only be made publicly available if there is no potential for the re-identification of individuals (). Thus, the data underlying this study are available on request to researchers once collapsed on the patterns of covariates. Data access requests should be addressed to info.epi{at}ausl.re.it.