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Covid Vaccine Q&A

Information correct as at 14 March 2022

There has been a lot of discussion in the media of both a third dose of COVID-19 vaccine and ‘booster’ programmes. This has caused some confusion; the following aims to explain who is eligible for each programme and how they differ from each other.

Who can get the Covid vaccine and how many doses?

As of 21 February 2022, the JCVI recommends that:

  • Children aged 5 to 11 who have blood cancer should have two vaccine doses (at a reduced dose).
  • Children aged 5 to 11 who live with someone who is immunosuppressed should have two vaccine doses (at a reduced dose).
  • People aged 12 and above who have blood cancer should have five vaccine doses (three primary doses and two boosters).
  • People aged 12 and above who live with someone who is immunosuppressed should have three vaccine doses (two primary doses and one booster).

How to book your fourth and fifth doses

If you have not yet booked your fourth (booster) dose of the Covid vaccine, follow the guidance for the UK country you live in.  From 21 March you are eligible for a fifth dose and you should follow the same procedure.


You can get your fourth dose (booster) at a vaccination centre if it’s been 3 months since your third dose, and you have a letter from a doctor. You can book an appointment online or go to a walk-in vaccination site.

If you had a letter from your doctor confirming your eligibility for the THIRD primary dose, you can use this letter at a vaccination centre to get your FOURTH booster dose too.

If you think you’re eligible for a fourth dose but you do not have a suitable letter, contact your GP or hospital specialist to ask for one. Show them this letter from NHS England which explains that they need to provide you with some written evidence for your fourth dose.

Although this is not NHS advice, if you don’t have this letter, we suggest you contact your vaccination centre and ask if they will accept other evidence of your eligibility such as:

  • a doctor’s letter showing that you had blood cancer at the time of your 1st or 2nd dose
  • evidence of the medication you were taking at the time of your 1st or 2nd dose – a hospital letter that describes the medication you were prescribed, a copy of your prescription or a medication box with your name and the date on it.

Not all centres can offer fourth doses. Use the online search to check for centres that say “3rd dose for people with a weakened immune system” as they should be able to provide fourth doses.

If your third primary dose was recorded as a booster, this doesn’t matter, you are still eligible for a fourth dose, and this will be recorded as a second booster.

You could download this FAQ document from NHS England about this, to help with any conversations with your doctor or vaccination centre.


If you had your third primary dose at least 3 months (12 weeks) ago, your health board should invite you for a fourth (booster) dose.

You can also book online or phone the free Scottish Covid Vaccination Helpline on 0800 030 8013 (8am to 8pm). For more information, see this web page from the NHS in Scotland.


If you had your third primary dose at least 3 months ago, your health board should invite you for a fourth dose. See this web page for Wales about third doses and boosters.

If you haven’t been invited for your fourth dose and it’s more than 3 months since your third dose, contact your health board.

Northern Ireland

In Northern Ireland, people will be identified by their Trust clinician or GP for a fourth dose. If you have a letter from your GP or another clinician confirming that you need a booster, you should be able to book online. See this web page from NI Direct about third doses and boosters.


What is the evidence for needing a fourth dose of the vaccine if you are immunocompromised?

Blood cancer patients were prioritised for the COVID-19 vaccine last year, due to many patients being clinically extremely vulnerable to COVID-19. Research has shown that those blood cancer patients who are immunosuppressed due to their condition and/or treatments, are less likely to have responded to the vaccine people with working immune systems. More work is needed to know which blood cancer patients are most likely to benefit from this. However, some protection is better than none, so it is recommended that you get the third dose you are offered in the hope you will see some benefits.

Should I bother with a fourth vaccine if I have not made antibodies to the vaccines so far?

We would encourage everyone who is eligible to take up the offer of the fourth vaccine. There is some evidence that it increases an immune response, including in people who did not make many antibodies. Some protection is better than none.

You do not need to test for antibodies before you have the fourth vaccine. Even if you have responded to the first three vaccines, we would encourage you to take up the fourth. Antibodies are only part of the immune system and the role of other parts of the immune system isn’t yet fully understood. It is possible that the fourth vaccine may yet boost your immune response further.

Is the third dose the same as the booster vaccine?

No. The third dose for the immunocompromised is an addition to the primary course (first two doses of the vaccine) to try and raise the level of immunity among the immunocompromised to match the immunity of the rest of the population.   Fourth (booster) doses were started early in 2022, and aren given approximately three months after you received the previous dose.


When and where will I receive my fourth vaccine?

Fourth doses for immunocompromised patients commenced early in 2022, and you should have been contacted by letter. If you are still waiting for your fourth vaccination, we suggest you contact your medical team immediately to confirm that you are eligible. All CLL patients, whether on Watch and Wait, in or post treatment qualify for the fourth, booster, vaccine. It is likely that you will have the vaccine from your GP, but some walk-in centres will also give it. If you still have problems, call 119 and explain that you are immunocompromised and they should refer you to a Covid Medicines Deliver Unit (CMDU).  Please refer to ‘How to book your fourth Dose’ above.

Does the Oxford Astra Zeneca vaccine cause blood clots?

Regulators in the UK and Europe have concluded that they may be an association between the vaccine and a very small number of cases of an extremely rare type of brain blood clot. This is not yet certain and there are several investigations going on to try to find out the true extent.

Initial results seem to indicate that people under 30 are the most likely to have a blood clot following the vaccination, and the majority are female. The reasons for this are unclear, but the under 30’s so far vaccinated often have other medical conditions that may make them more vulnerable.

How many of these clots have been reported?

In the UK at the time of writing, 79 cases have been reported and 19 have died. It is not yet known if this is a higher number than would be expected under normal conditions, but it is suspected to be the case.

What changes are being made?

People under 30 will now receive one of the other types of vaccine (currently Pfizer or Moderna).

I’ve been invited for a vaccine. Should I go?

Yes. The advice from all regulators is to have whatever vaccine you are offered. If you are under 30 you will be offered an alternative to the Astra Zeneca vaccine. The vast majority of CLL patients are over 30, so this will not apply. However, there are still a number of CLL patients who are between 30 and 60. Current evidence suggests that this group have an extremely low risk of getting blood clots.

What are the signs of a blood clot after being vaccinated?

The signs tend to develop between four and fourteen days after vaccination. The main sign is a severe headache which lasts for a few days and usual pain killers such as paracetamol have no effect. Another sign may be red specks under the skin away from the injection site, shortness of breath, swollen legs and bruising.

Reactions such as mild flu-like symptoms, aching muscles and joints and chills are common symptoms and usually resolve after a few days. These should not be confused with the symptoms of possible blood clots, and these should be referred to a doctor for treatment.

Are these blood clots treatable?

Yes. The British Society of Haematology says that this is very treatable if caught early. The main treatment will usually be intravenous immunoglobulin followed by blood thinners.

How do the vaccines work?

Vaccines work by preventing people from becoming severely ill and by stopping the spread of illness to others.

The advice from the Joint Committee for Vaccine and Immunisation (JCVI), the group which advises the government on vaccines, is that everyone who is offered a vaccine should have it. Our clinical advisers have also confirmed that this is the case.

However, it is not yet known whether any of these vaccines can prevent people from passing on the virus to other people who have not yet been vaccinated.

For this reason, if you do receive a vaccine, it is important you continue to observe social distancing and other actions to make sure that you do not spread COVID-19 unknowingly to non-vaccinated people. The vaccine will also take up to five weeks from the initial jab until it has become effective.

Is the vaccine safe?

Although the vaccines which will be available soon have been developed very quickly, they have to pass through a very stringent test and approval procedure. They must all be approved by the Medicines and Healthcare products Regulatory Agency (MHRA) following a thorough review of all the clinical data.
The advice from the Joint Committee for Vaccine and Immunisation (JCVI), the group which advises the government on vaccines, is that everyone who is offered the Pfizer or Oxford vaccine should have it. Our clinical advisers have also confirmed that this is the case.

None of the first three vaccines which will become available, the Pfizer-BioNTech, the Oxford – Astra Zeneca vaccine or the Moderna vaccine is a live vaccine. They are therefore suitable for CLL patients, who must not receive live vaccines.

Other vaccines are awaiting approval, and we will provide further information when approval is granted, should this be different from other vaccines in development.

If you have any concerns about receiving the vaccine, we advise that you speak to your medical team about it once you have received your invitation.


Will it work?

It is still not clear what degree of immunity CLL patients will receive from the vaccine. It is known that CLL patients do not respond as well to the flu vaccine, for example, as people with normal immune systems.
However, this does not mean that you will get no response at all, and some response, however small, would provide at least some protection. Our advice is, therefore, that you should have the vaccine if invited, provided there are no contra-indications, such as allergic response or pregnancy. Under 16s are also advised not to have it. Please check with your medical team if in any doubt.

It is important that you receive all doses of the vaccine. While some protection is provided from earlier doses, further doses will give at least some further protection, as there is evidence that the vaccine can start to gradually lose its effect over time.

Has the vaccine been tested on CLL patients?

We understand that neither the Pfizer vaccine nor the Oxford vaccine was tested in immunocompromised patients. However, our current advice is that those affected by CLL should have the vaccination when invited to do so. About 40% of the people vaccinated in the Pfizer trial were over 55, and it is thought that it works well in this population.

This study looked at 167 people with chronic lymphocytic leukaemia who had received both doses of the Pfizer vaccine 21 days apart. Of these 167 people, an antibody response was only seen in 39.5%. Those who were in remission following treatment had a better response than those who were on active treatment. While these results are worrying, it’s important to remember that antibody response is only one piece of the puzzle and other factors which weren’t measured in this study, might also be important in protecting people from covid. More research is needed to understand this.

However, it’s important to understand that your immune system worsens with age and is even more damaged in CLL patients. Any vaccine will not work as well as in the general population but may give at least some protection. Further research is required to establish what degree of protection.

I’ve had Covid – should I still be vaccinated?

It is not yet certain how much immune response will be generated by natural infection, and it’s also not clear how long this response will remain in the body.

Some studies have suggested that antibodies are short-lived after infection, and there have been cases of reinfection reported, although rare. Therefore, it is recommended that you still have the vaccination, as this has been designed to give lasting protection.

I am currently on chemo treatment – can I have the vaccine?

This is a group in which the Pfizer-BioNTech vaccine or the Oxford vaccine has not been specifically tested. We do not yet know who was tested in the trials for other vaccines in development. With other vaccines, such as childhood vaccinations or flu, there are specific times when these should be had whilst you are on chemotherapy, to give the vaccines the best chance of working. If you are invited for the vaccine during a course of chemotherapy, please speak to your team if you are unsure when is the most appropriate time to have it.

I have an allergy – is the vaccine right for me?

It has been reported that two of the first recipients of the Pfizer-BioNTech vaccine had experienced an anaphylactoid reaction after receiving the vaccine. This kind of reaction is where the person develops a range of symptoms including a rash, breathlessness, and a drop in blood pressure. It is important to note that this is not the same as an anaphylaxis reaction, which can be fatal. The two people affected had severe allergies, which meant that had to carry an epi-pen at all times. The NHS is no longer giving jabs to people with “significant” allergies; this is defined as “any person with a history of immediate-onset anaphylaxis to a vaccine, medicine or food”.

If you are unsure if this applies to you, please check with your GP or medical team before having the vaccine.