Abstract
Nonpharmaceutical interventions (NPIs) implemented to contain SARS-CoV-2 have decreased invasive pneumococcal disease. Previous studies have proposed the decline is due to reduced pneumococcal transmission or suppression of respiratory viruses, but the mechanism remains unclear. We undertook a secondary analysis of data collected from a clinical trial 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. Nasopharyngeal samples from children aged 24 months were assessed in three periods — one pre-COVID-19 period (n = 1,537) and two periods where NPIs were implemented with increasing stringency (NPI period 1 [NPI-1, n = 307], and NPI period 2 [NPI-2, n = 262]). Pneumococci were quantified using lytA quantitative PCR and serotyped by DNA microarray. Overall, capsular, and nonencapsulated pneumococcal carriage and density were assessed in each NPI period compared with the pre-COVID-19 period using unadjusted log-binomial and linear regression. Pneumococcal carriage was generally stable after the implementation of NPIs. In contrast, overall pneumococcal carriage density decreased by 0.44 log10 genome equivalents/mL (95% confidence interval [CI]: 0.19 to 0.69) in NPI-1 and by 0.84 log10 genome equivalents/mL (95% CI: 0.55 to 1.13) in NPI-2 compared with the pre-COVID-19 period. Reductions in overall pneumococcal density were driven by reductions in capsular pneumococci, with no corresponding reduction in nonencapsulated density. As higher pneumococcal density is a risk factor for disease, the decline in density provides a plausible explanation for the reductions in invasive pneumococcal disease that have been observed in many countries in the absence of a substantive reduction in pneumococcal carriage. IMPORTANCE The pneumococcus is a major cause of mortality globally. Implementation of NPIs during the COVID-19 pandemic led to reductions in invasive pneumococcal disease in many countries. However, no studies have conducted a fully quantitative assessment on the impact of NPIs on pneumococcal carriage density, which could explain this reduction. We evaluated the impact of COVID-19 NPIs on pneumococcal carriage prevalence and density in 2,106 children aged 24 months in Vietnam and found pneumococcal carriage density decreased up to 91.5% after NPI introduction compared with the pre-COVID-19 period, which was mainly attributed to capsular pneumococci. Only a minor effect on carriage prevalence was observed. As respiratory viruses are known to increase pneumococcal carriage density, transmission, and disease, this work suggests that interventions targeting respiratory viruses may have the added benefit of reducing invasive pneumococcal disease and explain the reductions observed following NPI implementation.
| Original language | English |
|---|---|
| Pages (from-to) | 1-9 |
| Number of pages | 9 |
| Journal | Microbiology Spectrum |
| Volume | 11 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 2023 |
Bibliographical note
Funding Information:Editor John M. Atack, Griffith University Copyright © 2023 Nation et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license. Address correspondence to Catherine Satzke, [email protected]. The authors declare a conflict of interest. C.S. is a lead investigator, and K.M. and C.D.N. are coinvestigators, on a Merck Investigator Studies Program grant funded by MSD outside of this work. K.M. is a lead investigator, and C.S. and C.D.N. are co-investigators, on a Pfizer funded study outside of this work. C.D.N. is on a Data Safety Monitoring Board outside of this work (no payment). J.B. prepared a report on pneumococcal serotypes for MSD outside of this work. J.H. receives project grants from Pfizer that are outside of this work and is a cofounder and board member of BUGS, Bioscience Ltd., a not-for-profit spin-out company (no personal payment). K.M. is a member of WHO SAGE committee (no payment) and K.M. and C.S. are Board members of ISPPD (no payment). None of the other authors have any competing interests to declare. Received 8 September 2022 Accepted 15 December 2022 Published 16 January 2023
Funding Information:
We thank the study participants and their families, the study staff, and the laboratory staff at the Pasteur Institute of Ho Chi Minh City and at the MCRI Translational Microbiology Group. C.S. and M.L.N. conceived this study with input from B.T. and S.M. B.D.O. and A.C.W.-H. conducted the laboratory analyses with oversight from C.S. J.H. contributed to the interpretation of microarray data. M.L.N. conducted the data analyses with input from C.S., B.T., and C.D.N. M.L.N., C.S., and S.M. prepared the original manuscript. L.T.T.V., T.L.P., and D.Y.U. coordinated the trial sites, with oversight from H.P.T. K.M. and T.V.N. are principal investigators of the vaccine trial, with contributions from B.T., H.P.T., K.B., V.T.T.D., C.S., H.S.-V., D.Y.U., J.B., and C.D.N. All authors reviewed and approved the final manuscript. The vaccine trial was supported by the Bill and Melinda Gates Foundation (grant number OPP-1116833/INV-008627). We also acknowledge the Victorian Government’s Operational Infrastructure Support Program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. C.S. is a lead investigator, and K.M. and C.D.N. are coinvestigators on a Merck Investigator Studies Program grant funded by MSD outside this work. K.M. is a lead investigator, and C.S. and C.D.N. are coinvestigators on a Pfizer-funded study outside this work. C.D.N. is on a Data Safety Monitoring Board outside this work (no payment). J.B. prepared a report on pneumococcal serotypes for MSD outside this work. J.H. receives project grants from Pfizer that are outside this work and is a cofounder and board member of BUGS Bioscience, Ltd., a not-for-profit spin-out company (no personal payment). K.M. is a member of the WHO SAGE committee (no payment) and K.M. and C.S. are Board members of ISPPD (no payment). None of the other authors have any competing interests to declare.
Funding Information:
The vaccine trial was supported by the Bill and Melinda Gates Foundation (grant number OPP-1116833/INV-008627). We also acknowledge the Victorian Government’s Operational Infrastructure Support Program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Publisher Copyright:
Copyright © 2023 Nation et al.
