Trial reportThe Journal of infectious diseases2025
Natural Carriage of Streptococcus pneumoniae Is Associated With Increased Experimental Pneumococcal Carriage but Reduced Conjugate Vaccine Efficacy in a Human Challenge Model.
Trial report in The Journal of infectious diseases, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
2 citing papers in PubMed.
- Controlled human infection with Mycobacterium tuberculosis: practical considerations for clinical trials.The Lancet. Microbe · 2026Review
- Pooled analysis of PCV13 efficacy from controlled human infection trials in Malawi and the UK.NPJ vaccines · 2026Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
30 authors.
Funding
Abstract
backgroundIn Malawi, the national 13-valent pneumococcal conjugate vaccine (PCV13) demonstrated less herd immunity than in the United States, likely due to higher natural pneumococcal carriage rates. We assessed PCV13 efficacy against experimental pneumococcal carriage in healthy Malawian adults. We explored how natural carriage (pneumococcal carriage of any serotype apart from 6B) influenced experimental carriage rates and vaccine efficacy.
methodsHealthy adults aged 18 to 40 years were randomly assigned to PCV13 (n = 98) or saline (n = 106), followed by intranasal SPN 6B inoculation at 20 000 (n = 40), 80 000 (n = 74), or 160 000 (n = 90) colony-forming units/100 µL at 28 days postvaccination. We evaluated natural and experimental pneumococcal carriage before and after vaccination on days 2, 7, and 14 postinoculation using culture and multiplex quantitative polymerase chain reaction (qPCR) targeting the lytA/cpsA genes, and we compared carriage rates by vaccination status.
resultsOf 204 participants, 19.6% (n = 40) exhibited experimental carriage detected by culture and 25.5% (n = 52) by qPCR. Vaccinated individuals had lower experimental carriage rates (10.2%, n = 10/98) than the placebo group (28.3%, 30/106). This difference in vaccine efficacy was more pronounced in participants without natural carriage (PCV13, 8%, 6/75; placebo, 25.9%, 21/81) vs those with natural carriage (PCV13, 14.8%, 4/27; placebo, 26.5%, 9/34). According to a log-binomial model, vaccine effectiveness (VE) was 62%, whether assessed by culture or qPCR. Natural carriers had lower VE (52%) vs participants with no natural carriage (69%).
conclusionsWe have shown that the PCV13 VE estimate (62%) is robust whether carriage is assessed by culture or qPCR. PCV13 had lower VE in natural carriers when compared with those without natural carriage at the inoculation visit.
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