Prevention of COVID-19 among older adults receiving pneumococcal conjugate vaccine suggests interactions between Streptococcus pneumoniae and SARS-CoV-2 in the respiratory tract.


Among 531,033 adults, there were 3,677 COVID-19 diagnoses, leading to 1,075 hospitalizations and 334 fatalities, between 1 March-22 July, 2020. Estimated aHRs for COVID-19 diagnosis, hospitalization, and mortality associated with prior PCV13 receipt were 0.65 (95% confidence interval: 0.59-0.72), 0.68 (0.57-0.83), and 0.68 (0.49-0.95), respectively. Prior PPSV23 receipt was not associated with protection against the three outcomes. COVID-19 diagnosis was not associated with prior PCV13 within 90 days following antibiotic receipt, whereas aHR estimates were 0.65 (0.50-0.84) and 0.62 (0.56-0.70) during risk periods 91-365d and >365d following antibiotic receipt, respectively.

While secondary pneumococcal pneumonia occurs less commonly after COVID-19 than after other viral infections, it remains unclear whether other interactions occur between SARS-CoV-2 and Streptococcus pneumoniae.

We probed potential interactions between these pathogens among adults aged ≥65y by measuring associations of COVID-19 outcomes with pneumococcal vaccination (13-valent conjugate and 23-valent polysaccharide; PCV13, PPSV23). We estimated adjusted hazard ratios (aHRs) using Cox proportional hazards models with doubly-robust inverse-propensity weighting. We assessed effect modification by antibiotic exposure to further test the biologic plausibility of a causal role for pneumococci.

Reduced risk of COVID-19 among PCV13 recipients, transiently attenuated by antibiotic exposure, suggests pneumococci may interact with SARS-CoV-2.

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