Nasal Bacillus Probiotic Linked to Fewer Infections

A 28-day randomized, double-blind, placebo-controlled trial found that LiveSpo Navax (LiveSpo Pharma), containing Bacillus subtilis ANA4 and Bacillus clausii ANA39, was associated with fewer newly detected viral and bacterial infections among preschool children than saline placebo according to an article published in Scientific Reports.

Investigators randomized 400 children aged 2 to 5 years at two preschools in Hanoi, Vietnam, who were asymptomatic or had mild respiratory symptoms. Participants used Navax (>1 × 10⁹ CFU/mL) or saline twice daily for 28 days. The per-protocol analysis included 390 completers: 194 in the Navax group and 196 in the placebo group.

The primary outcome was the incidence of five mild respiratory symptoms at day 28 versus baseline; medication use was a coprimary outcome. Symptoms generally decreased in both groups. Although several within-group reductions were statistically significant, neither the primary nor school-adjusted analyses found significant between-group differences for the five symptoms.

Among children without a detected viral infection at baseline, new infections at day 14 occurred in approximately 2% of the Navax group and 9% to 10% of the placebo group, a 6.1-fold difference (P=.002). Among those without a detected bacterial infection at baseline, new infections at day 28 were 2.03-fold less frequent with Navax (P=.047). Testing covered respiratory syncytial virus, influenza virus, rhinovirus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

No adverse events, serious adverse events, or treatment-related effects were observed. Limitations included per-protocol analysis, 28-day follow-up, scheduled testing, and enrollment at two preschools in one area. ANABIO R&D funded the study; one author founded LiveSpo Pharma, and another consulted for the company.

Source: Pham AT, Nguyen TTH, Bui HT, et al. Nasal-spray Bacillus probiotics reduce mild respiratory infections and the risk of new infections in preschool children. Sci Rep. Published online August 21, 2026. doi:10.1038/s41598-026-67075-y