Third dose of the Covid-19 vaccine

A third dose and additional booster dose (4th dose) of the coronavirus (COVID-19) vaccine is being offered to people aged 12 and over who had a severely weakened immune system.

Information on third dose Covid-19 vaccinations

The third primary dose is an extra ‘top-up’ vaccination given 8 weeks after your second dose.  The third dose will help to increase the level of protection for people who may not have generated a full immune response to the first two doses and might be less protected than the wider population.

A third dose is different from a booster dose.  A booster dose is a later dose to extend the duration of protection from the primary course of vaccinations.

If you are eligible for a third primary dose, you may also become eligible for an additional booster dose three months (91 days) after your second dose. 


You have been invited to have a third primary dose because you the NHS has identified you as someone who was severely immunosuppressed when you received your first or second dose of the COVID-19 vaccine.

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.

If you are eligible, the NHS will contact you to invite you for an appointment.   If you have not received an appointment and think you should have, please contact your GP or consultant to discuss your eligibility for a third dose.

Booster dose (4th dose) of the COVID-19 vaccine

A booster dose (4th dose) of the COVID-19 vaccine helps improve the protection you have from your first 3 doses of the vaccine.

It helps give you longer-term protection against getting seriously ill from COVID-19.

When to get your booster (4th dose)

If you've had a 3rd dose, you'll be eligible for a booster (4th dose) from 3 months (91 days) after your 3rd dose.

How to get your booster dose

A GP or your hospital specialist will invite you for your booster (4th dose) when it's due.

Most people can also book their appointment online or go to a walk-in COVID-19 vaccination site.

Book online

You can pre-book your booster dose online if you're aged 12 or over and it's been 2 months (61 days) since you had your 3rd dose.

  • You'll be offered appointment dates from 3 months after the date of your 3rd dose.
  • You’ll need to bring a letter from a GP or your hospital specialist inviting you for either a 3rd dose or a booster following your 3rd dose.
  • If you do not have a letter, contact your GP surgery or hospital specialist.

Frequently asked questions

Covid-19 Vaccination Services in Surrey

Vaccination services are running in a number of community locations.

You can find out more, including details of locations and availability of walk-in vaccination clinics with no appointments required on our Covid-19 vaccination centres page.  Please note walk-in vaccinations for Booster doses are currently limited.

Covid-19 Vaccination Resources

For a range of helpful resources, including information in community languages, research, videos and much more, visit our Covid-19 vaccination centres page.

A series of resources specific to third dose vaccinations can be found on the website.