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An immune-training capsule did not prevent wheezing in toddlers at risk of asthma, in an 822-child trial
OM-85, made from broken-down bacteria, is meant to teach young immune systems to cope with chest infections. Given for two years and followed for three more, it made no difference.
- A double-blind randomized trial of 822 children aged 6 to 18 months at raised risk of asthma.
- They took OM-85, a capsule of inactivated bacterial fragments, or placebo for 10 days a month for two years.
- Over the next three years off the capsules, 21% on OM-85 had a wheezing chest illness, against 18% on placebo.
- That difference is within chance: the treatment did not prevent wheezing.
- Side effects were no different, so the finding is about lack of benefit, not harm.
Parents of wheezy toddlers are offered a lot of things that promise to strengthen a child’s immune system, and most of them have little evidence behind them. OM-85 was a more serious candidate. It is a capsule made from broken-down, inactivated bacteria, and smaller studies had suggested it might cut the chest infections that so often come before asthma.
The ORBEX trial, published in The Lancet, tested it properly: 822 babies at raised risk of asthma, two years of treatment, three more years of watching. It did not prevent wheezing.
Why early wheezing matters for asthma
MedlinePlus notes that asthma often starts during childhood, usually before age 5, and that it is the most common chronic disease of childhood. It describes what the disease does to the airways: this can cause wheezing, coughing, and tightness in your chest.
In very young children, repeated wheezing with colds is one of the strongest early signs. The authors call wheezing lower respiratory tract illnesses a major health concern in preschool children, and preventing them has long been seen as one possible route to preventing asthma itself.
How the wheezing prevention trial was run
Every child had a reason to be at risk. The trial enrolled young children at increased risk for asthma due to atopic dermatitis, parental asthma, or asthma in a blood sibling. Atopic dermatitis is the medical name for eczema.
Children aged 6 to 18 months were given OM-85 or an identical placebo by mouth for 10 days each month for 24 months. The real test came afterward. The main outcome was the time until a first wheezing chest illness during three years off the capsules, which asks the question that matters: did the treatment leave a lasting mark on the immune system? Neither families nor staff knew who had which capsule, and active and placebo capsules were identical, so nothing about the daily routine gave the game away.
What happened to wheezing illness
The capsule made no difference. During the observation period, 71 of 342 children in the OM-85 group and 61 of 339 in the placebo group had at least one wheezing chest illness, which is 21% against 18%.
That slightly higher figure on OM-85 is well within chance, and the authors’ conclusion is plain: oral administration of OM-85 in early life did not decrease the incidence of wheezing lower respiratory tract illness in these children.
Safety was reassuring. The most frequent adverse events, fevers, coughs, and colds, did not differ between groups, so the result is about an absence of benefit rather than any sign of harm.
Why a careful null result on immune training matters
Immune-boosting products for children are an easy sell to worried parents, and they rarely face a trial this rigorous. This one ran for five years in total, was double-blind, and followed children long after treatment stopped. It enrolled exactly the children most likely to benefit, gave the product for long enough to have an effect, and then waited to see whether that effect outlasted the treatment. It is hard to design a fairer test, and the product did not pass it.
The authors go beyond the single product in their conclusion, writing that bacterial lysates are not efficacious for the primary prevention of asthma-like symptoms during the preschool years. That is a strong statement from a well-run trial, and it should weigh heavily on how these products are recommended for prevention.
What a toddler prevention trial cannot tell us
The trial tested prevention of a first wheezing illness in children who had not yet developed asthma. It did not test whether OM-85 helps children who already wheeze repeatedly or already have asthma, which is a different question some smaller studies have looked at.
Not every child completed the follow-up: 681 finished the two years of treatment and 596 the three years of observation. The study was also funded partly by the manufacturer, which provided the capsules, alongside the US National Heart, Lung, and Blood Institute; a negative result under those conditions is, if anything, more convincing.
What this changes for parents of wheezy toddlers
For a family with a child at risk of asthma, this is a reason not to spend money on a bacterial capsule in the hope of heading asthma off. It did not work for that purpose in a trial designed to find a benefit if one existed.
The things with better evidence are more ordinary: prompt treatment of wheezing episodes as a doctor advises, and keeping children away from tobacco smoke. If a child has been prescribed OM-85 for another reason, the sensible step is a conversation with the prescriber rather than stopping it unilaterally.
People also ask
What did the study find?
During the 36-month observation period off the study drug, 71 (21%) of 342 children in the OM-85 group and 61 (18%) of 339 in the placebo group had at least one wheezing lower respiratory tract illness. There was no significant difference, meaning nothing beyond what chance would produce, in time to first illness (hazard ratio 1.16, 95% CI 0.82-1.64). Fevers, coughs and colds did not differ between groups.
What is a bacterial lysate?
A preparation of bacteria that have been broken apart and inactivated, taken by mouth. The idea is that meeting these fragments trains the immune system to respond better to real respiratory infections.
Which children were in the trial?
Babies aged 6 to 18 months at raised risk of asthma because they had eczema, a parent with asthma, or an older brother or sister with asthma.
What is a wheezing lower respiratory tract illness?
A chest infection or cold that settles in the lower airways and causes wheezing, the whistling breathing that is often an early sign of asthma in young children.
Should parents stop using OM-85 if a doctor prescribed it?
This trial tested prevention of wheezing in high-risk toddlers, and found no benefit. It did not test every use. Talk to the prescriber before stopping anything. This is general information rather than medical advice.
Was the trial long enough?
Yes, by the standards of these studies: two years of treatment and three years of follow-up afterward, which is long enough to see whether any early training effect lasts.