Please note: Booster changes from 1 April 2023 - see here.


People who have a medical condition or are receiving therapies that affect the function of their immune system are at increased risk from severe COVID-19 illness. Vaccination is highly recommended but depending on the type and the level of immunocompromise they may not produces as good a protective response as a healthy person. This means that they are less well protected by the vaccine or their protection wanes to below protective levels faster. Extra doses of vaccine can help to overcome this reduced response.

Information for vaccination of severely immunocompromised people and eligibility is here.

Third primary doses

As part of the primary schedule, a third dose of Comirnaty (mRNA COVID-19 vaccine) is recommended for people aged from 5 years who were severely immunocompromised in proximity to their first or second primary doses. [For further detail see the Immunisation Handbook 2020 Chapter 5 (section 5.5.8)] Prescription and written consent are needed for third primary doses.

Preferably, the third dose should be administered at least eight weeks after the second dose. However, the timing also needs to consider current or planned immunosuppressive therapies. 

If there are current or planned immunosuppressive therapies, aim to delay the third dose of vaccine until two weeks after the period of immunosuppression, in addition to the time period for clearance of the therapeutic agent.

If an alternative to Comirnaty is required or requested, the second-line COVID-19 vaccine Nuvaxovid (Novovax) can be given as a third primary dose to those aged 18 years or older with a prescription.

Booster doses

Everyone aged from 16 years is recommended to receive a booster dose after their primary series. This includes people who had three primary doses. Individuals who are not eligible for a third primary dose but have moderately immunocompromising conditions are particularly recommended a booster dose.

Additional booster doses

An additional booster dose is recommended for severely immunocompromised people, aged 16 years and above, who received a three-dose primary course. Those aged over 30 years with moderate immunocompromise are also recommended an additional booster dose with bivalent Comirnaty, regardless of the number of previous doses received.

Booster eligibility can be found here or Immunisation Handbook Table 5.2.


Evusheld is a pre-exposure prophylaxis (PrEP) therapeutic treatment containing two long-acting monoclonal antibodies (tixagevimab and cilgavimab). It was indicated for protection of highly immunocompromised people but is now not recommended as it does not provide adequate protection against most of the currently circulating SARS-CoV-2 variants.

Further information

Ministry of Health information on third primary doses and immunocompromise.

Last updated: 10 May 2023