Weak immune system and COVID-19 vaccines

It is important that you are vaccinated against COVID-19 if you have a weak immune system (immunosuppressed or immunocompromised).

Having a weak immune system puts you at higher risk of serious illness if you get COVID-19. Getting vaccinated will give you some protection against this.

See the weak immune system conditions list

Booster doses needed

People with a weak immune system aged 5 and older should follow the recommended vaccination below:

  • 2 doses of the Pfizer vaccine, 4 weeks apart, as your first round of COVID-19 vaccination
  • an additional dose 8 weeks after this
  • a first booster 4 months after this
  • 2 seasonal boosters per year, in spring and autumn - wait 6 months since your previous dose or COVID-19 infection

How to get your vaccine

Book your COVID-19 vaccine appointment on a day and time that suits you.

Vaccines will be given in hospital if you're an inpatient. GPs may also vaccinate some people.

Additional dose

COVID-19 vaccines may be less effective for you than other people. If you had a weak immune system at the time of your first round of COVID-19 vaccination, you should have had an additional dose to give you better protection.

Talk to your hospital team or GP if you have not had your additional dose yet and you need one because of a weak immune system.

When you should get an additional dose

You should get an additional dose 8 weeks after your second dose. But you can get it 4 weeks after your second dose if you need to be protected urgently.

If you had COVID-19 after your second dose

If your COVID-19 infection was more than 7 days after the second vaccine dose, you do not need to get an additional dose. You should get your first booster dose 4 months after your COVID-19 infection.

If you get a COVID-19 infection within 7 days of your second dose, you should get an additional dose 4 to 8 weeks after your COVID-19 infection.

Weak immune system list

People with the following conditions or treatments should follow the recommended COVID-19 vaccination on this page.

Your GP or hospital consultant will confirm if you should get an additional dose or second booster at this time.

Cancer patients

Cancer patients affected include:

  • receiving or within 6 weeks of receiving systemic cytotoxic chemotherapy, targeted therapy, monoclonal antibodies or immunotherapies
  • receiving treatment or pending treatment for a haematological cancer
  • haematological cancer - within 5 years of treatment
  • undergoing or within 6 weeks of surgery or radiotherapy for lung or head and neck cancer
  • advanced metastatic cancer

Haematological cancer includes:

  • leukaemia
  • lymphomas
  • blood dyscrasias
  • other malignant neoplasms affecting the bone marrow or lymphatic systems
Chronic kidney disease

People who have chronic kidney disease:

  • on dialysis, or eGFR less than 15ml/min
  • eGFR less than 30ml/min

People who have:

  • been listed for solid organ or haematopoietic stem cell transplant (HSCT)
  • had a solid organ transplant at any time
  • had a HSCT in the past 12 months
Genetic diseases

People who have:

  • autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED)
  • inborn errors in the interferon pathway
  • some B and T cell deficiencies

People using any of the following for treatment:

  • Cyclophosphamide
  • Rituximab
  • Alemtuzumab
  • Cladribine
  • Ocrelizumab
High dose systemic steroids

The following doses of prednisolone (or equivalent dose of other glucocorticoid) are likely to be immunosuppressive:

  • adults and children over 10kg: ≥40mg/day for more than 1 week, or ≥20mg/day for 2 weeks or longer
  • children under 10kg: 2mg/kg/day for 2 weeks or longer

People living with HIV not on treatment, or who have CD4 count less than 200/10-6L for adults

Safety and side effects of COVID-19 vaccines

All COVID-19 vaccines used in Ireland are approved by the European Medicines Agency (EMA)

Safety and side effects of COVID-19 vaccines used in Ireland

Staying safe from COVID-19

Because your immune system may not respond as well to vaccination, you could still be at risk of becoming severely ill from COVID-19. You are also at risk of COVID-19 infection lasting for longer.

Avoid situations where you could pick up the virus, such as crowded areas.

Everyone you live with who can get vaccinated should get vaccinated against COVID-19. This will help to protect both you and them from COVID-19.

How COVID-19 affects people with a weak immune system, including information on steroids

Page last reviewed: 28 April 2023