This instalment was originally planned to cover the long-term safety of Covid-19 vaccines. However, over the past week, there have been quite a number of queries on severe allergic reactions (called anaphylaxis) in the context of Covid-19 vaccines.

As such, this segment will focus on answering this question: How likely is it that I will get a severe allergic reaction from a Covid-19 vaccine and how dangerous will this be?

Although many of us have been impatient to get the vaccines (and many have voiced this disgruntlement in various avenues including social media), even I as a vaccine proponent have been somewhat mollified by the time taken for the first set of Covid-19 vaccines to arrive here in our country.

The reason for this is simple. Thanks to this delay, we now have “precious” safety data from the roll-out of vaccination across different countries, numbering into the millions of individuals – and this data is more than strong enough to convince any naysayer or conspiracy theorist as to the imagined dangers of the vaccines.

The US, the UK and many European nations have very robust reporting mechanisms for documenting side effects of medications or vaccines being given. The US, for example, has the US Vaccine Adverse Event Reporting system which reports side effects from both healthcare workers giving the vaccines as well as from people who are vaccinated themselves. The UK has a similar reporting mechanism called the Yellow Card safety monitoring system which also captures the side effects of vaccines being administered.

Data available at this time of writing shows that the US has administered more than 60 million doses of Covid-19 vaccines (consisting mostly of Pfizer-BioNTech and Moderna which are MRNA vaccines); while the UK has administered more than 15 million doses (mostly of the Oxford-AstraZeneca vaccine which consists of a modified inactivated flu adenovirus).

One of the severe side effects individuals can get when taking a medication or receiving a vaccine is anaphylaxis, a rare but severe form of allergic reaction. Anaphylaxis happens within seconds or minutes of ingesting a medication or being injected with a vaccine.

Due to the exposure to this allergic substance, your body’s immune system immediately starts flooding your body with certain chemicals that cause you to go into shock – causing a drop in blood pressure and blocking your breathing. Indeed, the condition is life-threatening.

However, anaphylaxis not only occurs from drugs or vaccines. For allergic individuals, it can happen due to exposure to any kind of substance they are allergic to including peanuts, or being stung by a bee.

Let’s put this into perspective. Documented evidence shows us that the rates of food allergies in children below 18 years old to various foods is around 6% to cow’s milk; 2.5 % to egg; 3.6% to wheat; 1.3% to peanuts; and 1.3% to fish and shellfish. In the UK, hospital admission rates due to anaphylaxis are about 2.4 per 100,000 children below 18 (rates are far lower for adults).

In terms of the Covid-19 vaccines, these are the current anaphylaxis rates.

Though this may be a slight generalisation, the risk of anaphylaxis is quite low, and the risk is likely to be higher from food allergies. The analysis of the data is also quite clear: signalling that more than 80% of those who had anaphylaxis from the Covid-19 vaccine already had a documented history of allergies or allergic reactions and close to a quarter of them previously had anaphylactic episodes.

Two other points were of importance to note from the data analysis. First, while those who had anaphylaxis were hospitalised, NO deaths resulted and all these cases recovered. Second, 90% of anaphylactic episodes occurred within 30 minutes of being injected with the vaccine – which is the time period that you will be monitored within the health facility where you are given the vaccine.

So it seems unlikely for someone to actually develop anaphylaxis from the Covid-19 vaccine if they are not allergic to anything. For those who have known allergies or allergic reactions, should they be taking the Covid-19 vaccine? Read the box below to find out.

When the vaccination programme is rolled out, it is of low probability that someone who has never had an allergic response in their life will develop anaphylaxis from being given the vaccine.

Even then to cater to that unlikely probability, safety measures are in place to monitor you during the process and to ensure that if something untoward such as anaphylaxis occurs, it will be addressed immediately.

If you would like to get caught up on previous topics covered under this series, they are available as per the link below:

INFOVAX is a community education and awareness series on Covid-19 vaccines brought to you by the Malaysian Medical Association Public Health Society (MMA PHS). Feel free to ask questions and clear your doubts about Covid-19 vaccines by putting them to us at [email protected]. Your questions and answers will be collated and answered in the following sessions.