Impact of COVID-19 non-pharmaceutical interventions on pneumococcal carriage prevalence and density in Vietnam

Non-pharmaceutical interventions (NPIs) implemented to contain SARS-CoV-2 have decreased invasive pneumococcal disease. We undertook an observational study to evaluate the impact of NPIs on pneumococcal carriage and density, drivers of transmission and disease, during the COVID-19 pandemic in Ho Chi Minh City, Vietnam. While NPIs did not significantly impact pneumococcal carriage, mean capsular pneumococcal density decreased by up to 91.5% (1.07 log10genome equivalents/mL, 95% Confidence Interval: 0.74-1.41) after NPI introduction compared with the pre-COVID-19 period. As higher pneumococcal density is a risk factor for disease, the observed decline provides a plausible mechanism for the reductions in invasive pneumococcal disease.