In a study yesterday in The Lancet Infectious Diseases, its authors describe how a positive test for COVID-19 is associated with increased rates of diagnosis of various non–SARS-CoV-2 infections in the 12 months following an acute SARS-CoV-2 infection, even if the initial infection is mild to moderate.
They also found that patients hospitalized for COVID-19 infections were at greater risk for other infections in the year after illness, compared to patients who were hospitalized for influenza.
The study is based on data collected from the US Department of Veterans Affairs (VA) healthcare databases. The authors compared outcomes among 231,899 people with a positive COVID-19 test and 605,014 with a negative COVID-19 test (test-negative control group) from Nov 1, 2021, to Dec 31, 2023. Patient records were examined for a battery of 65 different laboratory tests for infectious illnesses in the 30 days to 12 months following documented COVID-19 illness.
Almost 50% higher rate of non-COVID respiratory infections
Compared with the test-negative control group, participants with a positive COVID-19 test who were not admitted had significantly increased rates of outpatient diagnosis of bacterial, fungal, and viral infectious illnesses (risk ratio [RR], 1.17; 95% confidence interval [CI], 1.15 to 1.19), outpatient respiratory infections (RR, 1.46), and admission to hospital for infectious illnesses (RR, 1.41), including for sepsis and respiratory infections.
Those data translate to increased risk of 17%, 46%, and 41%, respectively.
Overall, non-hospitalized COVID patients had higher rates in 32% of the 65 laboratory-based outcomes compared to those who tested negative for SARS-CoV-2.
That rate jumped in hospitalized COVID-19 patients, who had higher rates of positive results in 71% of the examined laboratory tests, after accounting for multiple comparisons with the COVID-negative cohort.
COVID may alter immune function
To further analyze the association between COVID-19 and subsequent infections, the authors compared people admitted to the hospital for seasonal influenza (3,293) and those admitted for COVID-19 (12,450) in the VA database and found that COVID patients had higher rates of admission to hospital for infectious illnesses (RR, 1.24), admission to hospital for sepsis (RR 1.35), and in-hospital use of antimicrobials (RR, 1.23).
In a commentary on the study, Gabriel Chodick, PhD, MHA, from Tel Aviv University, said these findings are important because they show that, even among patients with only moderate infection, COVID-19 seems to alter the immune system and make patients more vulnerable to future illnesses.
These findings have important implications for understanding the potential impact of COVID-19 on long-term immune function and susceptibility to pathogens.
"These findings have important implications for understanding the potential impact of COVID-19 on long-term immune function and susceptibility to pathogens," Chodick writes. "The evidence suggests effects extending beyond the acute phase of infection, affecting even mild cases."
