Vaccines against SARS‐CoV‐2 are safe to administer in patients with antibodies to pegaspargase

OBJECTIVE: Allergic reactions to pegaspargase during ALL therapy are typically due to antibodies against polyethylene glycol (PEG), which is also used as a stabilizing agent in mRNA‐based SARS‐CoV‐2 vaccines. To evaluate the safety of these vaccines in patients with anti‐pegaspargase antibodies. METHODS: We retrospectively reviewed the records of patients treated for ALL who had received SARS‐CoV‐2 vaccinations. All patients had antibodies against pegaspargase assayed during ALL therapy prospectively and in response to clinical allergies. Symptoms of intolerance to vaccination were gathered retrospectively from chart abstraction. RESULTS: SARS‐CoV‐2 vaccination was well tolerated in all 78 patients with prior exposure to pegaspargase as part of their leukemia therapy. No reactions were observed in the 54 patients without a history of anti‐pegaspargase antibodies or in 19 patients with antibodies who received mRNA vaccination. 1 patient who received the polysorbate containing Janssen vaccine experienced mild symptoms after vaccination not meeting the criteria of clinical allergy which spontaneously resolved within 25 minutes. CONCLUSION: SARS‐CoV‐2 vaccination is safe in this population.