Decreased Pneumococcal Carriage among Older Adults in Denmark during the COVID-19 Lockdown

Background: COVID-19 containment measures reduced the burden of invasive pneumococcal disease. Data on pneumococcal carriage rates among adults during the pandemic are scarce. Methods: Naso-and oropharyngeal swabs and questionnaires were collected during January 2019 to December 2021 from adults ≥64 years of age. Carriage was determined by lytA/piaB PCR. Results: A total of 1556 participants provided paired naso-and oropharyngeal swabs. Their median age was 74 years (IQR, 70-79). Streptococcus pneumoniae DNA was detected in 146 (9.4%) oropharyngeal swabs and 34 (2.2%) nasopharyngeal. The carriage rate decreased from 12.9% (95% CI, 10.1%-16.1%, n = 66/511) prelockdown (January 2019-February 2020) to 4.2% (95% CI, 2.0%-7.5%, n = 10/240) during lockdown (March 2020-February 2021) and increased to 12.1% (95% CI, 9.8%-14.7%, n = 87/719) with the reopening of society (March 2021-December 2021; P =. 0009). Conclusions: Pneumococcal carriage prevalence declined significantly during pandemic mitigation measures and rebounded to prepandemic levels as measures were lifted.