Many vaccines have been developed to check the spread of Covid-19 and the vaccines currently in use have been shown to be effective and safe in preventing COVID-19 disease, especially severe illness and death. Potential allergic reactions, including anaphylactic reactions to SARS-CoV-2 mRNA vaccines may occur but they are rare. The benefits of vaccination certainly outweigh the risks.
However, there was a perceived need for uniform recommendations for evaluation and management of individuals with a known or suspected allergy to the vaccine or any of its excipients.
Recommendations on the diagnosis and management of severe allergic reactions, including anaphylaxis to SARS-CoV-2 mRNA vaccines have been published in The Journal of Allergy and Clinical Immunology: In Practice. These evidence-based recommendations have been developed by a group of international experts. According to the panel, the incidence of SARS-CoV-2 vaccine anaphylaxis is 7.91 cases per million vaccinations, while the prevalence of polyethylene glycol (PEG) allergy is 103 cases per million. PEG skin testing has high specificity but poor sensitivity.
Some key recommendations are as follows:
- For patients with no history of a previous severe allergic reaction to a SARS-CoV-2 vaccine or its excipients, the risk of SARS-CoV-2 vaccine-induced anaphylaxis is very rare. Vaccination over no vaccination based on this risk is recommended.
- In patients with no history of a severe allergic reaction, including anaphylaxis, to SARS CoV-2 vaccines or its excipients, experts recommend against vaccine or vaccine excipient testing prior to vaccination in an attempt to predict the rare individual who will have a severe allergic reaction to vaccination.
- Routine skin or in vitro testing using SARSCoV-2 vaccines or excipients is not recommended outside of the research setting for the purpose of vaccine withholding, given such testing has unknown sensitivity/specificity in predicting severe allergic reactions, including anaphylaxis, to SARS-CoV-2 vaccines.
- A shared decision-making paradigm of care is recommended favoring vaccination through full or graded dosing (with or without additional observation time post-vaccination) or changing vaccine platforms to another agent over no vaccination because there is no single best approach to assessment and management of the patient with a suspected SARS-CoV-2 mRNA or adenovirus vector vaccine reaction, or the patient with an allergy to an excipient in either of these vaccines who has not yet been vaccinated.
- In patients with suspected immediate allergic reaction to SARS-CoV-2 vaccine whose standard schedule requires more than one dose, referral to an allergist is recommended for assessment of additional vaccination over no vaccination/vaccination being withheld.
- In patients with a suspected or confirmed but remote past medical history of reaction to a vaccine excipient, referral to an allergist is recommended for assessment of additional vaccination over no vaccination/vaccination being withheld.
- In patients with a definite/confirmed recent allergic reaction to COVID vaccine and/or excipient, referral to an allergist is recommended for assessment of additional vaccination over no vaccination/vaccination being withheld.
- SARSCoV-2 mRNA or adenovirus vector vaccine should be administered in a setting equipped to manage anaphylaxis, under the supervision of personnel trained in the recognition and management of anaphylaxis.
- Routine H1-antihistamine or systemic corticosteroid pre-medication prior to vaccination is not advised as it has low certainty evidence in preventing anaphylaxis, and theoretically corticosteroid pre-medication could diminish the immune response.
(Source: Medscape; J Allergy Clin Immunol Pract. 2021 Jun 18;S2213-2198(21)00671-1)
Dr Surya Kant, Professor and Head, Dept. of Respiratory Medicine, KGMU, UP, Lucknow.National Vice Chairman IMA-AMS