Daily oral S. salivarius K12 did not reduce AOM incidence or respiratory infections in children under 2 years; therefore, routine use for AOM prevention in general paediatric populations is not supported.
Key Findings
Results
Daily oral S. salivarius K12 did not significantly reduce the rate of doctor-recorded acute otitis media compared to placebo in children under 2 years.
AOM occurred in 70/180 (39%) placebo recipients and 70/188 (37%) probiotic recipients
Rate ratio 0.84, 95% CI 0.57–1.24, indicating no statistically significant difference
Analysis was by intention to treat using mixed-effects negative binomial regression adjusted for region and prior AOM, with random effects for general practice and family
368 of 428 randomised children (86%) contributed primary outcome data
Results
Time to first AOM episode did not significantly differ between the probiotic and placebo groups.
Hazard ratio 0.89, 95% CI 0.63–1.26
This was a pre-specified secondary outcome
Children were enrolled at 3–6 months of age and received daily study product from age 6 to 24 months
Results
No significant differences were observed for AOM severity, respiratory infections, antibiotic prescribing, or healthcare utilisation between the probiotic and placebo groups.
These were all pre-specified secondary outcomes
Antibiotic prescribing and healthcare utilisation were assessed across the full follow-up period from 6 to 24 months
Higher-adherence analyses were also not statistically significant
Methods
The trial was a multicentre, double-blind, randomised, placebo-controlled design conducted in New Zealand with household-level randomisation.
Conducted in Wellington and Christchurch, New Zealand
Households were randomised 1:1 to active or placebo treatment
A total of 428 children were randomised by household
The trial was prospectively registered (ACTRN12618000130268) on 30 January 2018, before enrolment of the first participant on 24 August 2018
Background
S. salivarius K12 has demonstrated antimicrobial and immunomodulatory activity in vitro and preventive effects in children with recurrent AOM, providing the rationale for this general population trial.
Prior studies showed preventive effects specifically in children with recurrent AOM
The probiotic is described as naturally occurring
The current trial aimed to determine efficacy in the general infant population rather than a high-risk subgroup
What This Means
This research tested whether giving infants a daily oral probiotic called Streptococcus salivarius K12 could prevent ear infections (acute otitis media, or AOM) and respiratory tract infections. The study enrolled 428 children in New Zealand starting at 3–6 months of age, and families were randomly assigned to give their child either the probiotic or a placebo every day until the child was 2 years old. It was a high-quality double-blind trial, meaning neither families nor researchers knew which product each child received.
The results showed no meaningful difference between the two groups. About 38–39% of children in both groups developed at least one doctor-diagnosed ear infection, and the statistical analysis confirmed this difference was not significant. Similarly, there were no significant differences in how quickly children got their first ear infection, how severe infections were, how often respiratory infections occurred, how many antibiotic prescriptions were written, or how often families sought medical care. Even when researchers looked only at children who took the probiotic consistently, no benefit was found.
This research suggests that while S. salivarius K12 showed promise in earlier, smaller studies focused on children who already had frequent ear infections, it does not appear to help prevent ear infections or respiratory illnesses in the broader population of healthy infants. The findings do not support routine use of this probiotic for ear infection prevention in young children generally, though the authors note this does not rule out potential benefits in specific high-risk groups.
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Halley C, Honeywill C, Kang J, Barnes P, Purdie G, Steenson G, et al.. (2026). Preventing otitis media and respiratory tract infections with the oral probiotic Streptococcus salivarius K12.. European journal of pediatrics. https://doi.org/10.1007/s00431-026-07379-3