Booster doses and third doses

NCL Wide

Update April 2022

COVID-19 vaccines for people with a weakened immune system download added. 

Update March 2022

From Monday 21 March, a spring booster of Covid-19 vaccine is being offered to:

  • people aged 75+
  • residents in care homes for older adults
  • those aged 12+ who have weakened immune systems.

Residents over 75 and those with weakened immune systems are advised to wait to be invited before booking an appointment. Invitations are being sent by SMS, email and letter during the week commencing 21 March, with the goal of having all invitations delivered by Friday 25 March.

Appointments will be offered at around six months (and not before three months) since the last dose of vaccine. Appointments can be made on the National Booking Service from Monday 21 March and the offer is also available at all walk-in clinics in NCL.

Roving teams will visit care homes for older people to vaccinate residents on site. Not all types of care homes are included in this offer; only those homes which are for older adults.


The NCL CCG website has updated public-facing information about booster doses and third doses for people with weakened immune systems.

New clinical guidance about third doses was published on 16 December 2021, see downloads section. 

What is the difference between booster doses and third primary doses? 

The primary course of the Covid-19 vaccine doses creates the immune response. For most people, two doses is enough to create an immune response but, for people who are immunosuppressed, a third primary dose is needed.  

Third primary doses are given as a full dose of either the Pfizer vaccine or Moderna vaccine from eight weeks after the second dose. AstraZeneca can be used as an option for patients who received it previously where this would facilitate delivery.

A booster dose is given to prolong the protection already created by the primary course. Booster doses are given as either a full dose of Pfizer or a half dose of Moderna from three months after the second dose. 

Eligibility for booster doses

Booster doses are available to everyone aged 16 and over from three months after their second dose. 

How and when to refer patients for boosters

GP practices should text all patients over 16 to invite them to book a booster dose two months after they received their second dose. All walk-in vaccination sites in NCL are also offering booster doses. 

All sites in North Central London have been asked to allow health and social care workers, those who are vulnerable and those receiving a first or second dose to bypass the main queue.

Download the new social media asset showing boosters for everyone aged over 16 below.

Eligibility criteria for third primary doses

The eligibility criteria for a third primary dose are set out in Appendices A B and C of the Clinical Framework for assessing patients presenting for additional doses due to immunosuppression (see downloads).

How will patients know if they can get a third primary dose?

Individuals can self-identify as potentially eligible for a third primary dose on the basis of severe immunosuppression by booking an appointment on NBS or attending a walk-in centre. Usually these individuals would present a letter from their GP or hospital consultant stating their eligibility for receipt of the third dose. In the absence of this letter, these individuals will require an assessment of their clinical eligibility. A third primary dose should be administered eight weeks after their second dose.

How and when to refer patients for third primary doses

NCL trusts have written to eligible patients in their care, copying their GP, to confirm that the individual is eligible for a third dose and to specify the optimal timing. GPs should follow up with these patients to invite them to book their third primary dose in line with the consultant’s advice. Patients aged 18 or over who have a letter from a GP or hospital consultant confirming their eligibility for a third dose can also go to a walk-in vaccination site.

GP teams should also identify their eligible patients. If you have eligible patients who have not received a third dose recommendation letter from their consultant, please contact the consultant to check that they have not been overlooked. 


Please see the other resources on this page for more information.

Clinical Framework updated 16 December 2021

Download PDF, 306.62 KB

Boost your immunity social media asset

Download JPG, 335.34 KB

Immunosuppressed third primary doses service script

Download PDF, 89.87 KB

Immunosuppressed third primary doses poster

Download PDF, 91.45 KB

Immunosuppressed Covid-19 vaccines criteria March 2022

Download PDF, 486.83 KB