A recent study published in the journal Allergy presents a significant shift in the management of pediatric fish allergies. Traditionally, the standard of care for young children with fish allergies has been strict dietary avoidance. However, this study explored whether codfish oral immunotherapy (OIT) could provide a more proactive approach by gradually training the immune system to tolerate the allergen. Researchers investigated whether structured exposure to codfish protein could induce either desensitization—the ability to safely consume the allergen while on therapy—or sustained unresponsiveness (SU), where protection remains even after treatment is paused.
The randomized, placebo-controlled clinical trial was conducted at Prince of Wales Hospital in Hong Kong and involved 70 children between the ages of 2 and 10 who were clinically reactive to codfish protein. Participants were randomly assigned to either a codfish OIT group or a placebo OIT group. Over 52 weeks, children in the treatment arm gradually increased their codfish protein intake until reaching a daily maintenance dose of 1000 mg. The primary endpoint was desensitization at week 52, measured by whether participants could successfully complete a supervised oral food challenge after one year of therapy.
Results showed that codfish OIT significantly outperformed placebo. Specifically, 43% of children receiving OIT achieved desensitization, compared to 11% in the placebo group. Researchers also found a “significantly greater increase in cumulative tolerated protein” among children receiving active therapy, with a median tolerated dose of 4330 mg compared to 0 mg in the placebo group. Although not every participant achieved full desensitization, many children experienced substantial increases in the amount of codfish protein they could safely tolerate, potentially lowering the risk of severe reactions from accidental exposure.
The findings for sustained unresponsiveness were more modest. After completing the 52-week treatment phase, participants avoided codfish for eight weeks before undergoing another food challenge. At that point, 23% of children in the OIT group maintained their tolerance, compared with 9% in the placebo group. However, this difference was not statistically significant. The researchers concluded that while codfish OIT effectively increases protection during active treatment, longer-term maintenance therapy or additional research may be needed to achieve more durable tolerance.
The study also documented important immunological changes associated with therapy. Children receiving codfish OIT showed significant reductions in codfish-specific IgE levels and skin-prick test reactivity, along with increased levels of codfish-specific IgG4, an antibody commonly associated with developing immune tolerance. Researchers additionally observed immunological evidence suggesting reduced cross-reactivity to salmon and catfish allergens. However, the authors cautioned that whether this translates into real-world clinical protection against other fish species still requires confirmation through formal food challenges.
Safety remains a major concern in all oral immunotherapy studies, and the investigators reported what they described as an acceptable safety profile. Most treatment-related reactions were mild, and the rate of epinephrine use was low, occurring in just 3% of participants in both the OIT and placebo groups. These findings suggest that codfish OIT can be administered relatively safely in carefully supervised clinical settings using structured dosing protocols.
Overall, the study provides strong evidence that codfish OIT can significantly improve desensitization rates in young children with fish allergy compared with placebo therapy. While sustained unresponsiveness remains limited, the ability to substantially raise reaction thresholds may still offer meaningful protection against accidental exposure and improve quality of life for affected families. The findings also open the door to future research exploring whether fish OIT could eventually provide broader protection across multiple fish species.
