Photo Credit: peterschreiber.media

The following is a summary of “Rates of infection with other pathogens after a positive COVID-19 test versus a negative test in US veterans (November, 2021, to December, 2023): a retrospective cohort study,” published in the April 2025 issue of Lancet Infectious Diseases by Cai et al. 

Researchers conducted a retrospective study to examine the association between a positive COVID-19 test and the risk of future infections with other pathogens compared to a negative test.  

They utilized the US Department of Veterans Affairs health-care databases to create a spatiotemporally aligned 2,31,899 individuals with a positive COVID-19 test and 6,05,014 with a negative test (test-negative control group) between Nov 1, 2021, and Dec 31, 2023. A discovery approach identified associations between COVID-19 positivity and laboratory-based infectious disease outcomes. Infection rates were then compared between those with and without COVID-19. To assess specificity, outcomes in hospitalized individuals with COVID-19 (n=12,450) were compared to those with seasonal influenza (n=3,293). Follow-up continued for up to 365 days post-test plus 30 days, death, or until July 18, 2024. Inverse probability weighting balanced demographic and health characteristics, and log-binomial regression models estimated risk ratios (RRs) and 95% CIs.  

The results showed that over 12 months, individuals with COVID-19 who were not hospitalized had higher test positivity rates for bacterial infections in blood, urine, and respiratory cultures, as well as viral diseases, including Epstein–Barr virus, herpes simplex virus reactivation, and respiratory viral infections, compared to those with a negative test. Hospitalized individuals with COVID-19 had increased bacterial infections in blood, respiratory, and urine biospecimens, along with viral infections in blood and respiratory biospecimens. Compared to the test-negative control group, non-hospitalized individuals with COVID-19 had higher rates of outpatient infectious illness diagnoses (RR 1.17 [95% CI 1.15–1.19]), including bacterial, fungal and viral infections; outpatient respiratory infections (RR 1.46 [1.43–1.50]); and hospital admissions for infectious illnesses (RR 1.41 [1.37–1.45]), including sepsis and respiratory infections, with rates generally higher among those hospitalized. Compared to individuals hospitalized for seasonal influenza, those admitted for COVID-19 had increased hospitalizations for infectious illnesses (RR 1.24 [1.10–1.40]), sepsis (RR 1.35 [1.11–1.63]), and in-hospital antimicrobial use (RR 1.23 [1.10–1.37]).  

Investigators concluded that a positive COVID-19 test, compared to a negative, had correlated with higher rates of subsequent diagnoses of various infections within the following year.   

Source: thelancet.com/journals/laninf/article/PIIS1473-3099(24)00831-4/abstract