Evaluation for the Risk of Allergy to COVID-19 Vaccines in People with History of Allergy Diathesis.

Background and rationale: Vaccination has formed the mainstay for mitigation of the COVID-19 pandemic. Vaccine-induced allergic reactions, though rare, have made it difficult to ensure complete coverage of COVID-19 vaccination. Initial guideline issued by the Government of India contraindicated vaccination in those with food or drug allergies. Allergic reactions largely result from excipients such as polysorbate 80 (P-80) (present in COVISHIELD™) and polyethylene glycol (PEG) [present in the messenger ribonucleic acid (mRNA) vaccines]. The present study was carried out with the objective of allergy testing in those with a history of allergic diathesis to generate objective evidence to the extent of true allergies to COVID-19 vaccination.

Materials and methods: After approval from the Institutional Ethics Committee, written informed consent was obtained for this prospective, open-label study in 100 participants. Allergic response assessment in participants with a history of any allergies, yet unvaccinated to COVID-19, or have taken the first dose and were due for second dose, or had taken the second dose and were due for the precautionary dose, was done by skin prick test (SPT) followed by intradermal testing (IDT) injection with COVISHIELD™ vaccine, P-80, and PEG individually. Based on the result of the skin test (either positive or negative), participants were given advice regarding vaccination.

Results: Of the 100 enrolled participants, n = 75 had taken both doses of any COVID-19 vaccine, n = 15 had taken only the first dose of any COVID-19 vaccine, and n = 10 were yet unvaccinated. There was no [0/92 (0%) and 0/98 (0%)] positive test with PEG and P-80, respectively. Only 02/98 (2.04%) returned a positive test with full strength (1:1) COVISHIELD™ vaccine IDT but not with SPT.

Conclusion: This study indicates a low risk of allergy to PEG, P-80, and COVISHIELD™. Where feasible, allergy testing and counseling can be offered to unvaccinated or partially vaccinated individuals with a history of allergic diathesis.