TreEAT: Clinical Implications, Screening Practices, and Next Steps, With Vicki McWilliam, MND, PhD

View part one of our conversation with McWilliam here.

Routine pre-screening of peanut-allergic infants for tree nut sensitization risks over-calling true allergy — and the TreEAT data offer quantitative support for that concern, with approximately 33% of infants sensitized to tree nuts at baseline yet true clinical allergy rates of just 12.4% (n = 11/89; 95% CI, 6.3–21.0%) in the home introduction arm and 18.9% (n = 18/95; 95% CI, 11.6–28.3%) in the multi-nut OFC arm on food challenge confirmation. Much of the reported ~30% peanut co-allergy rate cited in the tree nut literature, McWilliam suggested, may reflect sensitization rates rather than true allergy — an important distinction with direct implications for how allergists counsel families in clinic.

In the second part of HCPLive’s conversation with McWilliam at the American Academy of Allergy, Asthma & Immunology (AAAAI) 2026 Annual Meeting held in Philadelphia, Pennsylvania, from February 27 to March 2, she walked through the practical clinical takeaways from the preliminary TreEAT data and outlined the evidence gaps she most wants to address in follow-up work. On shared decision-making, her core message was that whichever introduction method a family chooses — supervised multi-nut OFC or graded home introduction — the data support that both can be pursued safely. No infant across either arm of the 212-patient single-center trial experienced anaphylaxis, providing a meaningful safety floor for clinicians having these conversations. McWilliam did note an important caveat around generalizability: the study's home introduction success rate likely reflects the heightened support families received as trial participants, and real-world uptake without that scaffolding may look different — consistent with the clinic observation that only about 25% of families were willing to attempt home introduction unprompted prior to the study.

McWilliam also flagged the study's limitations openly: single-center, conducted in Melbourne, and with a primary outcome assessed only at 18 months — a timepoint at which the immune system remains plastic and allergy status may still be in flux. Peanut allergy resolution was observed in 26.3% (n = 25/95; 95% CI, 18.0–36.7%) of the multi-nut OFC arm and 30.3% (n = 27/89; 95% CI, 22.0–42.1%) in the home introduction arm — broadly consistent with the approximately 20% resolution rate reported in the broader literature, and with co-allergy to tree nuts lower than previously reported figures. The unresolved question is whether infants who did not maintain ongoing nut exposure following the intervention have since developed further allergies — something only longer follow-up can answer. McWilliam described active efforts to secure funding for follow-up assessments at ages four and five, where those children now sit, with a full primary outcome paper expected for publication later this year.

“It was really reassuring to know out of those 200 infants that were introducing the tree nuts, either via home introduction or the malting up butter, we're not having anaphylaxis. So that was quite reassuring that whatever method we do with our families, that we've got a fair amount of safety data now to be able to say that this is something we're comfortable to do,” McWilliam said.

McWilliam’s reported disclosures include Nutricia.

Reference

McWilliam V, Parker K, Koplin J, et al. The TreEat Study: A Randomized Controlled Trial Investigating the Efficacy and Safety of Early Introduction of Tree Nuts for the Prevention of Tree Nut Allergy in Infants with Peanut Allergy. Presented at: AAAAI 2026 Annual Meeting, February 27-March 2, Philadelphia, Pennsylvania. Abstract #L15