SARS-CoV-2 infection and post-acute risk of non-Covid-19 infectious disease hospitalizations: a nationwide cohort study of Danish adults aged ≥50 years

Reports suggest that the potential long-lasting health consequences of SARS-CoV-2 infection may involve persistent dysregulation of some immune populations, but the potential clinical implications are unknown. In a nationwide cohort of 2,430,694 50+-year-olds, we compared the rates of non-Covid-19 infectious disease inpatient hospitalizations (of ≥5 hours) following the acute phase of SARS-CoV-2 infection in 930,071 individuals with rates among SARS-CoV-2 uninfected from 1 January 2021 to 10 December 2022. The post-acute phase of SARS-CoV-2 infection was associated with an incidence rate ratio of 0.90 (95% confidence interval 0.88-0.92) for any infectious disease hospitalization. Findings were similar for upper- (1.08, 0.97-1.20), lower respiratory tract (0.90, 0.87-0.93), influenza (1.04, 0.94-1.15), gastrointestinal (1.28, 0.78-2.09), skin (0.98, 0.93-1.03), urinary tract (1.01, 0.96-1.08), certain invasive bacterial (0.96, 0.91-0.1.01), and other (0.96, 0.92-1.00) infectious disease hospitalizations and in subgroups. Our study does not support an increased susceptibility to non-Covid-19 infectious disease hospitalization following SARS-CoV-2 infection. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement There was no specific funding for this study. No funder had any role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. ### 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 analyses were performed as surveillance activities analyses as part of the advisory tasks of the governmental institution Statens Serum Institut (SSI) for the Danish Ministry of Health. SSI's purpose is to monitor and fight the spread of disease in accordance with section 222 of the Danish Health Act. According to Danish law, national surveillance activities conducted by SSI do not require approval from an ethics committee. Both the Danish Governmental law firm and the compliance department of SSI have approved that the study is fully compliant with all legal, ethical, and IT-security requirements and there are no further approval procedures required for such studies. 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, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes No additional data available. Owing to data privacy regulations in Denmark, the raw data cannot be shared.