Skip to main content

COVID-19 vaccination: What to expect after – advice for children and young people

The NHS is offering the COVID-19 vaccine to all eligible children and young people.

This leaflet explains what to expect after your COVID-19 vaccination

Updated: 22 December 2021


― Side effects
― What to do if you are concerned about your symptoms
― Are there other more serious side effects?
― How COVID-19 is spread
― Can you catch COVID-19 from the vaccine?
― What to do next
― If you are not well for your appointment
― Will the vaccine protect you?
― What you can do after you’ve had the vaccine
― More information


Side effects

Like all medicines, vaccines can cause side effects. Most of these are mild and short-term and not everyone gets them. The very common side effects should only last a day or two. The Pfizer vaccine tends to cause more side effects after the second dose than the first dose.  

Very common side effects in the first day or two include: 

  • A heavy feeling or soreness where you had the injection
  • Feeling achy  or like you’ve  got the flu
  • Feeling tired
  • Having a headache

A mild fever may occur shortly after vaccination and last for a day or two, however a high temperature could also indicate that you have COVID-19 or another infection. An uncommon side effect is swollen glands in the armpit or neck on the same side as the arm where you had the vaccine. This can last for around 10 days, but if it lasts longer see your doctor. If you have any side effects after your vaccine, you can take the normal dose of paracetamol (follow the advice in the packaging) and rest to help you feel better.

What to do if you are concerned about your symptoms

These symptoms normally last less than a week. If your symptoms seem to get worse or if you are concerned, you or your parent or carer can look at: online, and if necessary call NHS 111 Wales on 111 or your GP surgery.  If 111 is not available in your area, call 0845 46 47. Calls to 111 are free from landlines and mobiles. Calls to 0845 46 47 cost 2p per minute plus your telephone provider’s usual access charge. If you do seek advice from a doctor or nurse, make sure you tell them about your vaccination (show them the vaccination card) so that they can assess you properly. You can report any side effects online at: or via the Yellow Card app.

Are there other more serious side effects?

Are there other more serious side effects? Recently, cases of inflammation of the heart (called myocarditis or pericarditis) have been reported very rarely after COVID-19 vaccines. These cases have been seen mainly in younger men within a few days after vaccination and are more common after the second vaccination. Most of these people recovered quickly and felt better following rest and simple treatments. You should seek medical advice urgently if you experience:

  • chest pain
  • shortness of breath
  • feelings of having a fast-beating, fluttering, or pounding heart

How COVID-19 is spread

COVID-19 is spread through droplets  breathed out from the nose or mouth, particularly when speaking or coughing. It can also be picked up by touching your eyes, nose and mouth after contact with contaminated objects and surfaces.

Can you catch COVID-19 from the vaccine?

You cannot catch COVID-19 from the vaccine but it is possible to have caught COVID-19 and not realise you have the symptoms until after your vaccination appointment. The most important symptoms of COVID-19 are recent onset of any of the following:

  •  a new continuous cough
  • a high temperature
  • a loss of, or change in, your normal sense of  taste or smell (anosmia)

Although a mild fever can occur within a day or two of vaccination, if you have any other COVID-19 symptoms or your fever lasts longer, stay at home and arrange to have a test by phoning 119 (calls are free) or online at: Get tested for Coronavirus (COVID-19).

After your vaccine, you should be given a record card. If you need a second dose your next appointment will be in about 8 to 12 weeks time. The second dose will give you longer lasting protection.

Keep your record card safe and remember to take it to your next appointment.

If you are not well for your appointment

If you are unwell, it is better to wait until you have recovered to have your vaccine. You should not attend a vaccine appointment if you are self-isolating, or waiting for a COVID-19 test or result.

Ideally you should wait at least 12 weeks following COVID-19 infection before getting your vaccine. During periods of high incidence or where there is concern about vaccine effectiveness (e.g. a new variant) this may be reduced to 8 weeks. You need to wait at least 4 weeks if you are in a group that is at greater risk of serious illness from COVID-19.

Will the vaccine protect you?

The COVID-19 vaccine that you have had has been shown to reduce the chance of you suffering from COVID-19 disease. Millions of doses of the vaccine have been given  worldwide. The vaccine is highly effective in children and young people. It may take a few weeks for your body to build up some protection from the vaccine. Like all medicines, no vaccine is completely effective, so you should continue to take recommended precautions to avoid infection. Some people may still get COVID-19 despite having a vaccination, but this should be less severe.

What you can do after you’ve had the vaccine

The vaccine cannot give you COVID-19 infection, and it will reduce your chance of becoming ill. It is still important to continue to follow current national guidance. You can continue going to school, college or work after you have had the vaccine. To protect yourself and your family, friends and colleagues, you should still:

  • think about social distancing
  • wear a face mask where advised
  • wash your hands carefully and frequently
  • open windows to let fresh air in
  • follow the current guidance at 

More information

You can find out more information about COVID-19 vaccines, including their contents and possible side effects at:

You can report suspected side effects online at: or by downloading the Yellow Card app.

To find out how the NHS uses your information, visit:

For other formats of this leaflet visit: