[Ask Dr Chiu] Risky dose? Let’s learn about vaccine allergy

[Ask Dr Chiu] Risky dose? Let’s learn about vaccine allergy

[Ask Dr Chiu] Risky dose? Let’s learn about vaccine allergy



5  Mins Read

On occasion, controversy arises around the skepticism about vaccination, especially among some parents. The commonest reason against jabs is the allergic effects they could trigger. Indeed, frightening cases of serious allergies go to the news once in a while. But first, what really is vaccine allergy? How severe and how frequent it can become?

Severe vaccine allergy is extremely rare

To start with, we have to recognise that vaccine allergy is an idiosyncratic drug reaction that varies from person to person. The most severe type is known as anaphylaxis, which is a critical clinical situation. The odds, though, are only around 1 to 2 cases per million of people receiving inoculation. Other side effects such as redness, itchiness, or fever, are usually localised and of short duration and is not the same thing as anaphylaxis.

What causes severe vaccine allergy? In a vial of vaccine, apart from the viral antigen, there are also substances such as protein, gelatin, stabilisers and preservatives. Amongst all, protein (egg white) is considered the most common culprit. This is the reason why, before a dose is administered, doctors or nurses would usually check whether the recipient has known history of protein allergy.

Anaphylaxis cases may need intensive care

Vaccine allergy, especially anaphylaxis is more associated with injectable vaccine, and less so with oral immunisation. It commonly develops in a few minutes to a few hours after injection, but in extreme cases, up to one or two days. Patients can present with swelling (a condition know as angioedema), shortness of breath, palpitation, dizziness and drop in blood pressure, in severe cases the person may also experience difficulty in breathing that can be life endangering. When it happens, anaphylaxis requires immediate medical attention. The person will need to be hospitalised, and if the condition becomes critical, requires intensive care.

Anaphylaxis, despite its rare occurrence, is a severe condition and requires enormous medical resources to save one’s life. In turn that implies high expenses. There is insurance company now offers free post-vaccination protection for the general public, covering all existing and future eligible vaccines – for instance the forthcoming COVID-19 jab. Anyone who registered will be offered hospital cash if he is unfortunately hospitalised after vaccination, which is an additional protection that can provide peace of mind for them.