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COVID-19 vaccination: guide for people with a weakened immune system

Updated 24 March 2022

People who have a severely weakened immune system are advised to have a third dose of coronavirus (COVID-19) vaccine. This is to help improve any protection you may have built from your first 2 doses and is given before your boosters.

What is COVID-19 or coronavirus?

COVID-19 is a very infectious respiratory disease caused by the SARS-CoV-2 virus. It can be very serious in people who have a weakened immune system. There is no cure for COVID-19 although some newly tested treatments do help to reduce the risk of complications.

Why you are being offered a third dose of the COVID-19 vaccine

This third dose is being offered to all those aged 5 years and older who had a weakened immune system around the time they had their first 2 doses of the COVID-19 vaccine. It is possible that you may not have responded as well as other people. This third dose may help to improve your immune response and give you better protection.

Your specialist can advise whether this applies to you. By having the third dose you may reduce your chance of catching the COVID-19 infection. And, if you do, the symptoms may be less severe and the illness shorter, than if you had not had the third vaccination.

People who need a third dose

People who need a third dose are those who had a severely weakened immune system around the time they had their first 2 doses. This includes those who had or have:

• blood cancers (such as leukaemia or lymphoma)
• lowered immunity due to treatment (such as steroid medication, biological therapy, chemotherapy or radiotherapy)
• lowered immunity due to inherited disorders of the immune system
• an organ or bone marrow transplant
• diseases that affect the immune system such as poorly controlled HIV
• other diseases or treatments as advised by your specialist

Timing of third dose

You will need 1 extra dose to improve your protection. Your extra (third) dose should be given at least 8 weeks after your second dose.

After that you may also need to have booster doses to extend your protection – any booster should be given from 3 months after your extra (third) dose.

Side effects

Very common side effects include:

• having a painful, heavy feeling and tenderness in the arm where you had your injection. This tends to be worst around 1 to 2 days after the vaccine
• feeling tired
• headache
• general aches, or mild flu-like symptoms

You can rest and take paracetamol (follow the dose advice in the packaging) to help make you feel better. Although feeling feverish is not uncommon for 2 to 3 days, a high temperature is unusual and may indicate you have COVID-19 or another infection.

Symptoms following vaccination normally last less than a week. If your symptoms seem to get worse or if you are concerned, you can call NHS 111.

How to get the vaccination

You can book online or go to a walk-in clinic for your third dose. To help the clinic check that you are eligible, please bring any letters from your GP or specialist or details of medication you are taking.

People who shouldn’t have the third vaccination

If you’ve had a very severe reaction to the previous dose of the vaccine, you should discuss this with your doctor.

If you have missed a vaccination

If you have not yet had either of your first 2 doses of the vaccine you should have them as soon as possible.

If it is now more than 8 weeks from your second dose, please arrange to have your extra (third) dose as soon as possible.

If you are aged 12 years or more, you will also need a booster. Your booster should be given from 3 months after your third dose.

If you have already had your booster, you will also become eligible for another booster this spring. If not, then you can have your booster soon as part of the spring campaign.

You will probably need another booster this autumn.

Further information

Coronavirus vaccination NHS.UK.

An information leaflet on what to expect after vaccination is available to download or order.