Third vaccine dose improves COVID-19 immune response in blood cancer patients

New research has found that the weakened immune systems of blood cancer patients can improve after a third COVID-19 vaccination.

Patients with lymphoma have defects in their immune system that restrict its response to vaccination. Despite this, this new study found improvements after a third vaccine dose, except in patients receiving a certain antibody treatment for their cancer.

The study, led by Southampton researcher Dr Sean Lim, has been published in the journal Nature Cancer.

Greater risk of severe COVID-19

Dr Lim, Associate Professor and Honorary Consultant in Haematological Oncology, said:

“Despite the gradual lifting of COVID-19 restrictions worldwide, a cloud continues to hang over immunosuppressed patients, who may not develop protective immune responses after vaccination.

“In particular, people with haematological malignancies are at greater risk of severe COVID-19 disease even if they have been vaccinated.”

Dr Lim and her team collected blood samples from 457 adult lymphoma patients.

Scientists measured the ability of antibodies in samples to prevent the viral spike protein from binding to ACE2 proteins, which are the virus’s key point of entry into the human body.

They also measured the response of T cells – which form part of the body’s immune system - when stimulated by the viral spike.

Antibodies tackling the virus

The results showed that just over half of patients undergoing active cancer treatment had no detectable antibody levels after the second vaccination. T cell responses could be detected in about two thirds of all patients.

After a third dose, 92% of patients who were not undergoing anti-CD20 treatment for their cancer showed improved antibody responses. This compared to 17% who were receiving that treatment.

Dr Lim explained: “We observed a good link between the level of antibodies in the blood samples and how well these antibodies blocked the virus from binding to the ACE2 protein. This suggests that the antibodies induced in patients with lymphoma perform similarly to those in healthy donors.”

Next steps for research

A key question for patients with suppressed immunity systems is whether there is a connection between antibody and cellular responses and the risk of infection, hospitalisation and death from COVID-19. The research team will follow up this research with further analysis into the clinical outcomes of patients in this study who were infected with COVID-19.

The study was funded by the Blood Cancer UK Vaccine Research Collaborative.