Effects of attenuated influenza virus administration to young children on pneumococcal density and acquisition in UK families: a randomised controlled trial
The Lancet Microbe·
- DOI
- 10.1016/j.lanmic.2026.101422
- PMID
- 42612652
- PMCID
- —
- OpenAlex
- W7203668241
- Study type
- Randomised controlled trial
- Publisher
- Elsevier BV
- Article type
- journal-article
- Integrity
- current
Why this research matters now
The findings suggest LAIV-induced increases in pneumococcal density in vaccinated toddlers may transiently raise pneumococcal acquisition risk among household members, which has implications for transmission modelling at individual and population scales.
Structured evidence summary
Research question
The study examined whether administration of LAIV to young children alters pneumococcal carriage density in those children and the likelihood of pneumococcal acquisition in their household contacts.
Study design
This was a randomised controlled trial conducted across ten UK sites (ISRCTN10720581), with 1:1 allocation of families to early or delayed LAIV groups. Laboratory and analytical staff were masked, while families and clinical staff were unmasked after randomisation.
Population and setting
Families with a 2-year-old index child eligible for a first NHS LAIV dose and at least two additional household contacts were enrolled in the UK. 405 households (1379 participants) were randomised; 96% of households completed the study.
Main findings
Compared with unvaccinated children, vaccinated index children had roughly 2.5-fold higher odds of increased pneumococcal density at day 14, and their household contacts had about 2.0-fold higher odds of acquiring pneumococcus. By day 28 these differences were no longer statistically significant. Three pregnancy/breastfeeding-related serious adverse events were reported and judged unrelated to the study.
Public-health relevance
The findings suggest LAIV-induced increases in pneumococcal density in vaccinated toddlers may transiently raise pneumococcal acquisition risk among household members, which has implications for transmission modelling at individual and population scales.
Important limitations
The abstract does not list explicit study limitations. This summary is limited to the supplied single-article abstract and metadata and requires the full paper for decision-grade interpretation.
GIDS interpretation
The paper addresses vaccine-related microbial transmission dynamics, classifying under influenza and vaccination topics, which supports its discoverability in literature searches on LAIV effects or pneumococcal carriage rather than confirming any live surveillance signal.
Related GIDS surveillance
Literature context does not validate, explain, or change a surveillance signal. Exact and contextual relationships are shown separately.
Evidence relationships
This article has 9 auditable classifier relationships to diseases, places, topics, and study design.