29th May 2021
A study from the University of Birmingham has been published looking at antibody response to covid vaccinations in 299 people with chronic lymphocytic leukaemia (CLL) who had two doses of either the Pfizer or AstaZeneca vaccine. 13 of these people had their first and second vaccines three weeks apart and the rest waited 12 weeks. The team found that after one dose of the vaccine, 34% of people with CLL had an antibody response to vaccination which rose to 75% after the second vaccination. In comparison, 100% of healthy donors had an antibody response after the two doses of the vaccine. Whilst 75% of people developed an antibody response, the actual quantity of antibodies produced was lower compared to those who were healthy. Those who were receiving a BTK inhibitor as treatment for their CLL were less likely to develop antibodies, as were those who had an “IgA deficiency” which is a deficiency of one kind of antibody that is characteristic of CLL. Having said this, 83% of people on “watch and wait” developed antibodies.
This is the biggest study we’ve seen in people with CLL and the results are similar to the CLL study from the Memorial Sloan Kettering Cancer Center, New York but there are still a number of unanswered questions. First, this study looked at antibodies using “dried blood spots” which is a technique that involves people pricking their own fingers and sending a spot of blood to be analysed. This technique isn’t as accurate as taking fresh blood from people. It’s also important to remember that this study didn’t look at the number of T cells people had, which are also thought to be important in protecting people from covid. It is possible that people who didn’t produce antibodies may have produced a T cell response which could be beneficial.
Lastly, in those who did produce antibodies, we don’t know what the quality of those antibodies are and we don’t know how much protection they give you. It could be that even though the quantity of antibodies produced was lower compared to healthy participants, the ones that are produced could be really efficient at fighting covid. Equally, it could be that the antibodies produced aren’t effective and this something we need to continue to study and will take time to answer. The Blood Cancer UK Vaccine Research Collaborative will continue to try and find answers to these questions over the coming months. As we wait to get answers to these questions, it’s important for all people with CLL, whether on treatment or not, to remain cautious.
You can find the full results here.
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