Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Feb 4;231(1):e17-e27.
doi: 10.1093/infdis/jiae351.

Pneumococcal Carriage and Disease in Adults in England, 2011-2019: The Importance of Adults as a Reservoir for Pneumococcus in Communities

Dima El Safadi  1 , Lisa Hitchins  1 , Ashleigh Howard  1 , Parvinder Aley  2   3 , Jaclyn Bowman  2 , Marta Bertran  4 , Andrea Collins  1 , Rachel Colin-Jones  2 , Filora Elterish  2 , Norman K Fry  4 , Stephen S Gordon  1 , Kate Gould  5   6 , Jason Hinds  5   6 , Emilie Horn  1 , Angela Hyder-Wright  1 , Rama Kandasamy  2 , Shamez Ladhani  4 , David Litt  4 , Elena Mitsi  1   2 , Annabel Murphy  1 , Andrew J Pollard  2 , Emma Plested  2   3   7 , Sherin Pojar  1 , Helen Ratcliffe  2 , Maria C Robertson  1 , Hannah Robinson  2   3   7 , Matthew D Snape  2   3 , Carla Solórzano  1   2 , Merryn Voysey  2 , Elizabeth Begier  8 , Julie Catusse  8 , Maria Lahuerta  8 , Christian Theilacker  8 , Bradford D Gessner  8 , Karen S Tiley  2 , Daniela M Ferreira  1   2
Affiliations

Pneumococcal Carriage and Disease in Adults in England, 2011-2019: The Importance of Adults as a Reservoir for Pneumococcus in Communities

Dima El Safadi et al. J Infect Dis. .

Abstract

Background: Pneumococcal carriage in healthy adults and its relationship to invasive pneumococcal disease (IPD) is not well understood.

Methods: Nasal wash samples from adults without close contact with young children (Liverpool, UK), 2011-2019, were cultured, and culture-negative samples tested by polymerase chain reaction (PCR). Pneumococcal carriage in adults 18-44 years was compared with carriage among pneumococcal conjugate vaccine-vaccinated children aged 13-48 months (nasopharyngeal swabs, Thames Valley, UK) and national IPD data, 2014-2019. Age group-specific serotype invasiveness was calculated and used with national IPD data to estimate carriage serotype distributions for ≥65 years.

Results: Overall, 98 isolates (97 carriers) were identified (3 solely by PCR) from 1631 ≥18 years adults (standardized carriage prevalence 6.4%). Despite different carriage and IPD serotype distributions between adults and children, serotype invasiveness was highly correlated (R = 0.9). Serotypes 3, 37, and 8 represented a higher proportion of adult carriage than expected. Predicted carriage serotype distributions for ≥65 years aligned closest with the young adult carriage serotype distribution.

Conclusions: Nasal wash technique is highly sensitive. For some serotypes carried by adults aged ≥65 years, other adults may be an important reservoir for transmission. Age groups such as older children should also be considered.

Keywords: adults; carriage; invasive pneumococcal disease; pneumococcal; transmission.

PubMed Disclaimer

Conflict of interest statement

Potential conflicts of interest. M. D. S. has been an investigator on behalf of the University of Oxford for studies funded or otherwise supported by vaccine manufacturers including GlaxoSmithKline, Janssen, Pfizer, Novavax, and MCM vaccines. Since 2022, M. D. S. has been employed by Moderna Biotech Distributors UK and holds equity in Moderna Inc. N. K. F. and D. L.'s laboratory has received grant funding from vaccine manufacturers for investigator-led research on pneumococcal carriage and disease. J. H. has received project grants (all payments to institution) from Pfizer. A. J. P. is Chair of the UK Department of Health and Social Care Joint Committee on Vaccination and Immunisation. B. G., J. C., C. T., E. B., and M. L. are employees of Pfizer and may hold stock and/or stock options. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Figures

Figure 1.
Figure 1.
Serotypes detected in carriage in adults aged ≥18 years, 2011–2019, Liverpool, England (98 isolates from 97 adults). Abbreviations: NT, nontypeable; PCV, pneumococcal conjugate vaccine (number indicates valency).
Figure 2.
Figure 2.
Comparison of adult (2014–2019) and children's (2014–2015 and 2017–2019) pneumococcal carriage serotype distributions. Abbreviations: NT, nontypeable; PCV, pneumococcal conjugate vaccine (number indicates valency).
Figure 3.
Figure 3.
Adult (2014–2019) and children's (2014–2015 and 2017–2019) pneumococcal carriage serotype distributions overlaid (gray) and subtracted from one another to show excess isolates in each distribution. Abbreviations: NT, nontypeable; PCV, pneumococcal conjugate vaccine (number indicates valency).
Figure 4.
Figure 4.
Comparison of child (13–48 months) and adult (18–44 years) carriage and invasive pneumococcal disease isolates, 2014–2019. To assist comparison of serotype distributions, this is for serotypes included ≥1% in carriage and/or disease for children and/or adults only. Serotypes are shown in numerical order within vaccine group. Abbreviations: IPD, invasive pneumococcal disease; NT, nontypeable; PCV, pneumococcal conjugate vaccine (number indicates valency).
Figure 5.
Figure 5.
Case-carrier ratios per 100 000 population, children aged 13–48 months (2014–2019) vs adults aged 18–44 years (2014–2019), for serotypes with at least 1 case and carrier detected across both cohorts. Larger circles indicate more confidence. Line with shaded confidence intervals is weighted linear regression line: log10(y)= 0.7181 + 0.8820*log10(x), R  2 = 0.8.
Figure 6.
Figure 6.
Age ≥65 years predicted carriage serotype distributions based on ≥65 years national invasive pneumococcal disease data, calculated with young adult (18–44 years) and child (13–48 months) case-carrier ratios. Abbreviation: PCV, pneumococcal conjugate vaccine (number indicates valency).
See this image and copyright information in PMC

References

    1. Ganaie F, Saad JS, McGee L, et al. A new pneumococcal capsule type, 10D, is the 100th serotype and has a large cps fragment from an oral Streptococcus. mBio 2020; 11:e00937-20. - PMC - PubMed
    1. Miller E, Andrews NJ, Waight PA, Slack MP, George RC. Herd immunity and serotype replacement 4 years after seven-valent pneumococcal conjugate vaccination in England and Wales: an observational cohort study. Lancet Infect Dis 2011; 11:760–8. - PubMed
    1. UK Health Security Agency, Department of Health & Social Care . Pneumococcal: the Green book, chapter 25. 2023. https://www.gov.uk/government/publications/pneumococcal-the-green-book-c.... Accessed 18 July 2024.
    1. Ladhani SN, Collins S, Djennad A, et al. Rapid increase in non-vaccine serotypes causing invasive pneumococcal disease in England and Wales, 2000–17: a prospective national observational cohort study. Lancet Infect Dis 2018; 18:441–51. - PubMed
    1. Chalmers J, Campling J, Ellsbury G, Hawkey PM, Madhava H, Slack M. Community-acquired pneumonia in the United Kingdom: a call to action. Pneumonia (Nathan) 2017; 9:15. - PMC - PubMed

MeSH terms

Substances