4-in-1 booster side effects
When the 4-in-1 pre-school booster does cause side effects, they are most likely to happen within 48 hours of the injection being given.
They include the following:
Very common reactions to the pre-school booster
More than 1 child in 10 having the pre-school booster vaccine experiences:
- loss of appetite
- irritability
- restlessness
- crying
- mild fever
- pain, redness and swelling at the injection site
Common reactions to the pre-school booster
Between 1 child in 10 and 1 child in 100 who has the pre-school vaccine experiences:
Uncommon reactions to the pre-school booster
Between 1 child in 100 and 1 child in 1,000 who has the vaccine experiences:
Rare or very rare reactions to the pre-school booster
Less than 1 child in 1,000 who has the vaccine experiences convulsions (fits).
Severe allergic reactions
Severe allergic reactions can happen with any vaccine, but they are extremely rare - they happen in fewer than one in a million vaccinations.
The healthcare staff who give vaccinations are trained to deal with severe reactions and children recover completely with treatment.
To find out more, read Vaccine safety and side effects.
Monitoring the safety of vaccines
In the UK, the safety of vaccines is routinely monitored through the Yellow Card Scheme by the MHRA and the Committee on Safety of Medicines. Levels of disease and vaccine uptake are recorded by the Health Protection Agency, to measure the impact of vaccines on disease.
Most reactions reported through the Yellow Card Scheme have been minor reactions such as rashes, fever, vomiting, and redness and swelling where the injection was given.
Find out how to report a vaccine side effect.
Last Updated: 17/02/2022 15:59:45
The information on this page has been adapted by NHS Wales from original content supplied by
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nhs.uk