Abstract
Background
Reports suggest that the potential long-lasting health consequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may involve persistent dysregulation of some immune populations, but the potential clinical implications are unknown. We investigated the associated risk of hospitalization due to non–coronavirus disease 2019 (COVID-19) infectious diseases following the postacute phase of SARS-CoV-2 infection.

Methods
By cross-linking data from the comprehensive Danish test and surveillance system for COVID-19 together with nationwide healthcare and demographic registers, we established a study cohort of 2 430 694 individuals aged ≥50 years, from 1 January 2021 to 10 December 2022, with no evidence of SARS-CoV-2 infection prior to study entry. Using Poisson regression, we compared the outcome rates of non-COVID-19 infectious disease hospitalizations following the acute phase of (a first) SARS-CoV-2 infection (defined as ≥29 days since the day of infection) in recovered individuals with rates among SARS-CoV-2–uninfected individuals.

Results
Among 2 430 694 included individuals (mean age, 66.8 [standard deviation, 11.3] years), 930 071 acquired SARS-CoV-2 infection during follow-up totaling 4 519 913 person-years. The postacute phase of SARS-CoV-2 infection was associated with an incidence rate ratio (IRR) of 0.90 (95% confidence interval [CI]: .88–.92) for any infectious disease hospitalization. Findings (IRR [95% CI]) were similar for upper respiratory tract (1.08 [.97–1.20]), lower respiratory tract (0.90 [.87–.93]), influenza (1.04 [.94–1.15]), gastrointestinal (1.28 [.78–2.09]), skin (0.98 [.93–1.03]), urinary tract (1.01 [.96–1.08]), certain invasive bacterial (0.96 [.91–1.01]), and other (0.96 [.92–1.00]) infectious disease hospitalizations and in subgroups.

Conclusions
Our study does not support an increased susceptibility to non-COVID-19 infectious disease hospitalization following SARS-CoV-2 infection.