Pneumococcal Positivity Associated With More Severe COVID-19 Outcomes

New data published by investigators in PLOS One demonstrates that the detection of Streptococcus pneumoniae, the bacterium that can cause pneumococcal disease, through a diagnostic test was linked to heightened mortality and worse outcomes in patients hospitalized with severe COVID-19, affirming the risk of coinfection and highlighting the importance of protective measures such as vaccination.¹

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Bacterial coinfection presents as a severe risk for patients infected with any respiratory disease, but especially SARS-CoV-2. Research and real-life observations have affirmed such risk. During the pandemic, a significant portion of patients with COVID-19 who died also harbored a secondary bacterial infection. Higher mortality corresponds with a greater likelihood of requiring invasive mechanical ventilation (IMV) and admission to the intensive care unit.^1,2

Streptococcus pneumoniae (S pneumoniae) presents as one of the most common and dangerous bacterial pathogens identified in patients with COVID-19. As one of the most common pathogens responsible for invasive pneumococcal disease and community-acquired pneumonia, it can cause severe lower respiratory tract infection. This is especially true when the bacterium is interacting with other respiratory viruses, like SARS-CoV-2; patients with both severe COVID-19 and S pneumoniae have been observed to have increased pneumococcal colonization.^1,3,4

Accurate diagnostic methods are critical to better coinfection detection efforts. Tools like urinary antigen tests (UATs) and multiplex polymerase chain reaction (PCR) assays are standard options for diagnosis. Despite some specificity limitations, they are routinely used in clinical settings and aid pharmacists and health care professionals in identifying coinfections and guiding antimicrobial therapy. Using these tools, the authors of the current study sought to determine whether S pneumoniae positivity is related to adverse clinical outcomes in COVID-19.¹

This retrospective cohort study, conducted at Chonnam National University Hospital from January 2020 to June 2023, included patients who were aged at least 18 years, diagnosed with COVID-19, and underwent UAT and multiplex PCR testing for S pneumoniae. A total of 507 patients with COVID-19 underwent such testing, with 280 ultimately being included in the analysis. Among this sample, 215 patients tested negative for S pneumoniae, while 65 tested positive.¹

The investigators compared characteristics between pneumococcus-positive and pneumococcus-negative patients. In-hospital mortality rates were significantly higher among patients positive for pneumococcus compared with those negative (33.8% vs 19.1%, P = .017). Severe illness was observed in 156 (55.7%) of the sample, with 39 (25.0%) having pneumococcal positivity; the overall mortality rate for severely ill patients was 35.3%, according to the authors. For patients with severe COVID-19, patients positive for S pneumoniae had significantly higher mortality rates compared with those negative for the bacteria, according to a subgroup analysis.¹

Distinct differences were observed in the clinical characteristics and outcomes between patients positive and negative for pneumococcus and with severe COVID-19. Among these patients, those positive for pneumococcus were more likely to have hypertension (74.4% vs 53.8%, P = .024) and chronic heart disease (51.3% vs 31.6%, P = .027), though they had a lower prevalence of solid cancer. Interestingly, there were comparable rates of the use of therapeutic agents, including antivirals, corticosteroids, and antibiotics. Overall patient mortality was meaningfully higher in the pneumococcus-positive group compared with the pneumococcus-negative group (53.8% vs 29.1%, P = .009).¹

“In our study, pneumococcal positivity was identified as an independent risk factor for increased mortality among patients with severe COVID-19 compared to those without pneumococcal positivity,” the study authors concluded. “This finding likely reflects a greater probability of true pneumococcal co-infection among patients with more severe disease.”¹

REFERENCES

1. Yoon C, Park H, Park H, et al. The influence of pneumococcal positivity on clinical outcomes among patients hospitalized with COVID-19: A retrospective cohort study. PLOS One. 2025. doi:10.1371/journal.pone.0329474

2. Cox MJ, Loman N, Bogaert D, et al. Co-infections: potentially lethal and unexplored in COVID-19. The Lancet Microbe. 2020;1(1):E11. doi:10.1016/S2666-5247(20)30009-4

3. Fan H, Zhou L, Lv J, et al. Bacterial coinfections contribute to severe COVID-19 in winter. Cell Research. 2023;33:562-564. doi:10.1038/s41422-023-00821-3

4. Halpern L. Nonpharmaceutical Interventions Can Disrupt Dynamics of Pneumococcal Disease. Pharmacy Times. Published August 21, 2025. Accessed August 28, 2025. https://www.pharmacytimes.com/view/non-pharmaceutical-interventions-can-disrupt-dynamics-of-pneumococcal-disease