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Retterer et？al1 note that their patient reacted to zoster vaccine, and then was primarily found to be sensitized to gelatin 3？years later, without alpha-gal–specific IgE. In their assessment, the best explanation is that the gelatin-specific IgE is more likely the culprit in the previous reaction to zoster vaccine than alpha-gal–specific IgE. They suggest for this specific patient that tick bites inoculate other antigens such as gelatin that could potentially sensitize the patient.2 Alternatively, we suggest that before the availability of alpha-gal–specific IgE testing the patient may have had positive specific IgE to alpha-gal (and gelatin and beef), but the circulating alpha-gal–specific IgE antibody concentrations diminished over time, as is frequently observed in our clinics when patients successfully avoid further tick bites and red meat.