News & Media > Update on JCVI recommendations for 3rd COVID vaccine doses and boosters: 24 September 2021

Update on JCVI recommendations for 3rd COVID vaccine doses and boosters: 24 September 2021

This guidance was updated on 17 December 2021; click here to see that update

Friday 24 September 2021

We recommend all clinics have clear, accessible patient information on third doses vs boosters and the differences in terms of timing and access.

A third primary dose is conceptually different to a booster:

  • A third dose is intended to improve response to the initial vaccine course in people who are less likely to ever have responded optimally. It is therefore described as being part of the “primary” vaccine course.

  • A booster enhances immunity in those likely to have experienced an optimal response to the initial vaccine but whose immunity has naturally waned over time, estimated by the JCVI to be between 6 and 8 months following the second vaccination in the primary course.

Third doses

On the 1st September 2021 the Joint Committee on Vaccination and Immunisation (JCVI) produced advice on third primary dose COVID vaccination for people with immunosuppression at the time of their first two vaccine doses [1]. The guidance applies to all people aged 12 or older.

People who receive a third dose will likely be eligible for booster doses (6 months after their most recent primary dose). The JCVI has not yet decided if people eligible for a 3rd dose will definitely need a booster and further advice will be provided on this.

It is not recommended to routinely measure immune responses after vaccination to determine the need for a third dose.

There are several indications for a third COVID vaccine dose [1]. JCVI recommends a third dose for people with HIV if their CD4 was less than 200 cells/mm3 at the time of initial vaccination. However, there is room for clinical judgement in deciding who should have a 3rd dose.

People with HIV who do not have an HIV-related need for a third vaccine but have another relevant immunosuppressive condition should be offered a third dose.

Evidence to guide specific advice for people with HIV is scant, and the relative impact on natural and vaccine-induced immunity of current CD4, CD4:8 ratio and detectable viral load is unknown.

We recommend, in line with JCVI, a third COVID vaccine dose for all people with a CD4 less than 200 cells/mm3 at the time of initial vaccination.

We suggest that the following groups are also offered a third vaccine dose:

1) People with clinical manifestations of HIV-related immune suppression, regardless of CD4 (e.g. AIDS-defining conditions, tuberculosis);

2) People with persistent or recurrently detectable plasma HIV-RNA after more than 12 months on antiretroviral therapy;

3) People not on recommended antiretroviral therapy (this does not apply to people who are maintain good immune markers off ART e.g. elite controllers).


On 14th September 2021 the JCVI produced guidance on booster doses for several groups, including all people living with HIV, which are summarised in The Green Book [2]. Essentially, everyone who was in priority groups 1-9 for initial COVID vaccine are eligible for a booster. This includes all people living with HIV.


Third doses

The logistics and a template invitation letter have been communicated by letter [3].

It is down to specialist services and/or GPs to identify and inform people who are eligible for a third vaccine dose - there is no planned central mechanism.

  • HIV services should proactively identify, and contact, people with HIV who need a third dose.

  • HIV clinics are advised to inform GPs where someone should have a third dose, and any specific related to timings (see below).

  • GPs have been informed of the need to offer third doses.

  • There is no central booking mechanism – for people not registered with a GP, or who have not shared their HIV status with their GP, please explore local options for referring directly to a vaccine hub. If you work within a Trust that does run a vaccine hub this should be relatively straightforward, if not we suggest liaising with other centres in your network who may be able to assist. Otherwise contact your local ICS or CCG lead.


Full details are pending but self-referral or online booking will be available for those who receive a letter notifying them that they are eligible for a booster. It is likely that the options to receive a booster will be broader than the options to receive a third dose and they are currently being considered.

Boosters and third doses will be coded differently. Ultimately, as long as people in need of a third dose get a third vaccine, it’s not overly important whether that is coded as a third dose, or a booster. However, assuming the JCVI do eventually recommend a booster for people with immunosuppression we recommend services keep a record of patients eligible for a third dose so that they can be contacted again should the need for a booster arise.


Based on JCVI advice:

  • The third dose, if required, should be given at least 8 weeks after the second and as soon after that time point as possible;

  • Boosters should be given at least 6 months after the second vaccination in the primary course.

This is where advice to patients and GPs must be particularly clear; there is a risk that people who need a third dose, but access it as a booster, will have their third dose delayed inappropriately.

Of note, some people with HIV are being offered a third dose when they do not meet the criteria – this vaccine will, in effect, be their booster. The only issue here is that they could receive their booster dose early (i.e. less than 6 months after their second vaccine); but this should be fine as long as it is more than 8 weeks after their second vaccine.

Vaccine type

JCVI recommends that the third dose should be an mRNA vaccine. People whose initial course was AstraZeneca can have a third AstraZeneca dose where this would facilitate delivery. Only exceptionally should someone whose initial course was mRNA be given an AstraZeneca booster; there are no specific circumstances where this would be recommended for someone with HIV unless there are at high risk of reinfection and unable to access an mRNA booster.



2) Greenbook COVID-19 chapter 14a (

3) C1399-Updated-JCVI-guidance-for-vaccinating-immunosuppressed-individuals-with-third-primary-dose.pdf (

For further information, please contact [email protected] or for media enquiries, please contact Jo Josh at [email protected] or +44 (0)7306 391875.