This guidance was updated on 24 September 2021; click here to see that update
On the 1st September 2021 the Joint Committee on Vaccination and Immunisation (JCVI), who advise the Government about vaccines, gave advice on a third dose of the COVID vaccination . All adults in the UK have been offered two doses of COVID vaccine but a third dose will currently only be offered to people with suppressed immune systems, that is people whose immune system is weaker because of medical conditions or treatments . This guidance applies to all people aged 12 or older.
People with weak immune systems are more likely to have a lower, or even no, response to two COVID vaccine doses in responses measured by blood tests. There is some evidence to show that a third dose can lead to better responses. Studies to date have not shown a greater risk of side effects for a third dose. A third dose is advised because people who are less likely to develop strong responses to the vaccine are also at higher risk of severe COVID.
No – not everyone with HIV needs a third dose of COVID vaccine. Evidence to date from studies which include people living with HIV shows that people with HIV who are undetectable do respond as well to vaccination as people who do not have HIV. Most people in studies had high CD4 counts (above 350) and there is some evidence that shows people with a low CD4 count respond less strongly to vaccination, which is why they may be offered a third dose.
The JCVI recommends everyone living with HIV aged 12 years or older with a CD4 count less than 200 should have a third dose now. BHIVA supports this recommendation and also advises a third dose for the following people:
1) People who had a serious HIV-related illness in the 12 months before their first COVID vaccine dose (e.g. AIDS-defining illness, tuberculosis).
2) People not taking recommended HIV treatment. (However, there are a few people who are able to control the virus and maintain a high CD4 count without treatment, known as Elite Controllers, who will not need a third dose.)
3) Some people who have a detectable viral load despite treatment. Their clinic will consider other things like their CD4 count and talk to them on a one-to-one basis about whether a third dose is needed.
HIV clinics have been asked to identify and contact people who need a third dose, and then to liaise with the patient’s GP. If your HIV clinic has contacted you about a third dose, but you do not hear from your GP directly, please contact the practice to arrange a vaccine.
If your clinic has contacted you about a third dose, and you are not registered with a GP, they will refer you to a vaccine centre.
The third dose should be given at least 8 weeks after the second dose. If you have a low CD4 count, and have just started HIV treatment, your clinic may advise you to wait a few weeks for your third dose.
JCVI recommends that the third dose should be an mRNA vaccine, such as Pfizer or Moderna.
However, people who have already had two doses of the AstraZeneca vaccine can have a third AstraZeneca dose if there is no mRNA vaccine available. In exceptional circumstances, AstraZeneca can be given as the third dose after two doses of mRNA vaccine – for example, when someone has had significant side effects to an mRNA vaccine.
Blood tests have been used in research trials to measure how strongly someone has responded to the COVID vaccine. However, it is not currently recommended that blood tests are done to decide if a third vaccine is needed. This may change as we learn more about what blood results are important for protection against COVID.
The priority at the moment is for a third dose to increase the level of protection from COVID for people with a weakened immune system. Two doses are not enough to give them the same level of response to the vaccine as people who have a normal immune system.
It is likely that in the future people over 50 will also be offered a booster vaccination to top up their vaccine response, but the timing for this has not yet been decided.
People with a weakened immune system who receive a third dose now will still be eligible for these extra doses, which would likely be six months after the third dose. Guidelines on this are awaited.