- Design
- Systematic review and meta-analysis of prevalence studies
- Population
- 35,704 children under five with diarrhoea in lower-middle-income countries
- Primary outcome
- Prevalence and genotypes of rotavirus and norovirus
- Effect
- Rotavirus 24% (95% CI 19.6–28.3%); norovirus 13% (11–15%); I² 98.7%
Investigators pooled studies of 35,704 children under five with diarrhoea in lower-middle-income countries that had introduced rotavirus vaccination. Rotavirus was detected in 24% and norovirus in 13%; together about one in five episodes had one or both.
Among rotavirus strains, G3P[8] was the commonest at 39%, followed by G1P[8]. Norovirus genogroup II predominated, with GII.4 responsible for about half of norovirus cases.
Heterogeneity was extreme (I² about 99%), so the pooled prevalence is a rough average across very different settings rather than a figure for any one country. The message for clinicians is not that vaccines fail, but that a vaccinated child with watery diarrhoea can still have rotavirus, and that norovirus is now a substantial share. Management is unchanged: oral rehydration and zinc, with antibiotics reserved for dysentery or specific indications. India's programme uses indigenous rotavirus vaccines; whether shifting genotypes affect their effectiveness is a surveillance question this review cannot answer.
- Do not exclude rotavirus because a child has been vaccinated.
- Treat acute watery diarrhoea with oral rehydration salts and zinc, whatever the virus.
- Avoid antibiotics for acute watery diarrhoea without dysentery or another specific indication.
- Reinforce hand hygiene in households and crèches, as norovirus spreads readily and alcohol gels work poorly against it.
- Continue to complete the rotavirus vaccine schedule on time.
Why it matters
It is a reminder that vaccination lowers severe rotavirus disease but does not remove viral diarrhoea from the clinic.
Don't overread it
This is pooled prevalence, not a measure of vaccine effectiveness.
The statistics, in plain English
An I² near 99% means almost all the variation between studies reflects real differences in setting, timing and testing rather than chance, so the pooled 24% should not be applied to a particular district.
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