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Pre-vaccination Screening Service



Diagnosis of
Allergy

Treatment for
Allergy

Joint Collaborative Severe
Asthma Service

Pre-vaccination Screening Service




The Government of HKSAR announced in February 2021 a territory-wide COVID-19 Vaccination Programme for all Hong Kong residents. This is a welcome development in the fight against the Covid-19 pandemic.

To date, most of the side effects of the vaccines have been relatively mild and short-lived (e.g. fever, headache, fatigue, muscle and joint pains). However there have been some patients so far who have experienced anaphylaxis, which is a severe allergic reaction, after receiving the messenger RNA (mRNA) vaccines. Over 70% developed the reactions within 15 minutes of injection.

Anaphylactic reactions caused by anti Covid-19 vaccines are rare, in the order of 10 per 1 million doses given. The cause of the severe allergy following COVID-19 vaccination is unknown and there is no precedent as these mRNA vaccines are new. Historically, reactions to other vaccines are seldom caused by the active ingredients. Instead, inactive ingredients, such as the excipients polyethylene glycol (PEG) and polysorbates added to improve solubility, are the commonest causes of reactions. Over recent years, excipients have been recognised as hidden allergens that may be causing repeated reactions in patients with hitherto undiagnosed severe allergic reactions to multiple classes of drugs.

Health authorities worldwide acknowledge that the risk of severe illness and death from COVID-19 outweighs the risk of developing anaphylaxis after vaccination. Nonetheless some individuals having a past history of allergies are sufficiently fearful of developing severe reactions that they refuse vaccination.

The HKSH Lee Tak Hong Allergy Centre at HKSH is therefore pleased to announce that it has established a service to help pre-screen individuals who may be at risk of developing an allergic reaction to COVID-19 vaccines, including detailed testing of the excipients, PEG and polysorbates. This involves completion of a screening questionnaire and if the person is deemed to be at risk, further skin and/ or blood tests will be performed to assess the presence of possible allergy to the excipients such as PEG and polysorbates.

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