COVID-19 Vaccine – what are the side effects?

By now, all of us know that vaccination for COVID-19 is not too far away but should we be worried about the side effects? Well, we know that all drugs have side effects and whilst we prefer medicines that cause the least problems for the patient – this may not always be possible. Importantly, it is easy to forget about the benefits of drug therapy (immunity to COVID-19 with the vaccine) by concentrating too much on its possible adverse effects.

Interestingly, when we discuss side effects, we break it down into four basic groups depending on how often it happens – also known as “incidence” of adverse effects;

  1. Very common – side effects occur in one (or more) out of every 10 people (≥ 10%)
  2. Common – side effects occur in one (or more) out of every 100 people (≥ 1/100) but less than one in ten people (< 1/10)
  3. Uncommon – side effects occur in one (or more) out of every 1,000 people (≥ 1/1,000) but less than one in 100 people (< 1/100)
  4. Rare – side effects occur in one (or more) out of every 10,000 people (≥ 1/10,000) but less than one out of every 1,000 people (1/1,000)
  5. Very rare – effects occur in less than one out of every 10,000 people (< 1/10,000)

For example: If one out of 800,000 people suffers an extreme reaction to a new drug then this is considered to be exceedingly rare, and not very likely to increase the overall risk for the general population.

This is the case with COVID-19 Astra Zeneca vaccine in Europe where 25 reports (mostly women under 55 years of age) out of 20 million vaccinations died from unusual blood clotting problems. Whilst every death is tragic there may be unique circumstances why these patients reacted so badly to the vaccine – some may have had pre-existing blood disorders.
Even so, the European Medicines Association recommends that if a patient gets any of the following symptoms, they should see their doctor as soon as possible and definitely mention that they had the vaccine recently.

The following may be exceedingly rare and serious side effects to COVID-19 vaccine (Astra Zeneca):

  1. breathlessness,
  2. pain in the chest or stomach,
  3. swelling or coldness in an arm or leg,
  4. severe or worsening headache or blurred vision after vaccination,
  5. persistent bleeding,
  6. multiple small bruises, reddish or purplish spots, or blood blisters under the skin,

And below, we have some more common side effects from COVID-19 Vaccine, generally:

  1. Pain, redness, and swelling on the arm where you got the needle – try applying a cool wet washcloth and exercise your arm a little.
  2. General tiredness, headache, muscle pain, chills, and fever – drink plenty of fluids and dress lightly if you have a fever.


When should you call the doctor or visit the hospital?

  1. If redness or tenderness gets much worse after 24 hours
  2. If side effects don’t go away after a few days.
  3. If you suffer any severe allergic reaction (rash, breathing problems) or any of the exceedingly rare and serious side effects above.

Remember if you get the second vaccine, some of the side effects that you experienced the first time around may become more intense the second time.

Crucially, it will take a couple of weeks (or longer) to develop some good immunity to COVID-19, so it is important to protect yourself and others during that time by;

  1. Wearing a mask.
  2. Maintaining social distancing and isolating yourself when sick.
  3. Avoiding big crowds where possible.
  4. Washing your hands before eating, preparing food, before and after using public toilets, removing your mask, and touching your face.
  5. Cleaning and disinfecting all surfaces, especially if you are caring for other people.
  6. Covering your mouth and nose if you cough or sneeze and getting rid of old tissues, properly (rubbish bin).
  7. Seeking medical advice if you suddenly develop symptoms such as fever/chills, cough, runny nose, sore throat, breathing problems, fatigue, aches and pains, loss of taste or smell, nausea/vomiting and or diarrhoea – and get tested for COVID-19!

In the end, it is important to realise that we need to get as many people as possible vaccinated so that COVID-19 becomes nothing more than a mild case of the “cold and flu”.

Emmanuel Pippos, Consultant Pharmacist.

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