Veterans hospitalized with influenza or respiratory syncytial virus (RSV) face a significantly elevated risk of secondary Streptococcus pneumoniae infection, while those with COVID-19 appear to have a reduced risk, according to a new national retrospective study spanning a decade of Veterans Affairs hospital data.
Researchers analyzed outcomes among 188,721 hospitalized patients tested for viral respiratory infections at VA hospitals across the United States between January 1, 2015, and March 1, 2025. Of these patients, 8,165 developed S. pneumoniae infection within 30 days of a viral diagnosis. The analysis revealed that individuals with recent influenza or RSV infections were more than twice as likely to develop pneumococcal disease compared to those without viral infection. Specifically, the odds ratios (OR) were 2.39 (95% CI, 2.15–2.64) for influenza and 2.50 (95% CI, 2.07–2.99) for RSV.
In contrast, COVID-19 was associated with a markedly lower risk of secondary S. pneumoniae infection, with an OR of 0.56 (95% CI, 0.50–0.62). This finding contrasts with long-standing clinical concerns around post-viral bacterial pneumonia, which have historically focused on influenza pandemics.
Risk was also elevated among current smokers (OR 1.09, 95% CI, 1.03–1.16) and patients with chronic obstructive pulmonary disease (COPD) (OR 1.36, 95% CI, 1.28–1.45), reaffirming the importance of targeted prevention in these high-risk populations.
These findings offer a nuanced understanding of the differing impacts respiratory viruses have on bacterial co-infection risk. While pneumococcal superinfections remain a major concern with influenza and RSV, clinicians may consider stratifying risk differently in COVID-19 cases. The data support ongoing vigilance for secondary bacterial pneumonia in select viral infections and underscore the importance of vaccination and early diagnostic protocols.
References:
Powers LA et al. Secondary Pneumococcal Disease in Veterans with Viral Respiratory Infections. Clin Infect Dis. 2025:ciaf285.
