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.