In April 2022, ZonMw facilitated a second international webinar about people with less well-functioning immune systems. During this webinar, results about the effect of COVID-19 vaccines in people with a congenital immune disorder and haematology patients were shared.

Contribution to the vaccination strategy

Policymakers can use this knowledge to make good choices in the vaccination strategy for these patients and those treating them. Furthermore, thanks to this webinar, the results also came to the attention of international researchers who are working on related subjects.

The functioning of the immune system in patients with immune disorders

Patients with immune disorders or disruptions of the immune system suffer from disorders in the functioning of the immune system, as a result of which they have an increased risk of infections, a higher chance of becoming severely ill from infections, and often do not respond as well to vaccinations. In these people, B cells produce few, if any, antibodies after vaccination.

B and T cells are part of the specific immune response to viruses. Some T cells can attach to a virally infected cell so that it dies. B cells can produce antibodies that attach to the pathogen so that the virus can no longer penetrate the cells.

Do COVID-19 vaccines protect people with immune disorders?

During the webinar, the researchers from the VACOPID and COBRA-KAI studies shared their results. These are two of the eight studies that ZonMw has funded concerning the effect of COVID-19 vaccinations for immunocompromised patients.

VACOPID study: vaccination for people with congenital immune disorders

The VACOPID study investigated the effect of the COVID-19 vaccines in people with a congenital immune disorder. These people have congenital defects in the functioning of their immune system and therefore make few, if any, antibodies to protect themselves against infections.

Various congenital immune disorders

This group of patients can be divided into different subgroups of patients ranging from those who produce sufficient antibodies to those who produce no antibodies. During this webinar, three groups of patients with congenital immune disorders were discussed:

  • Patients with X-linked agammaglobulinaemia (XLA). These patients do not usually produce any antibodies.
  • People with Common Variable Immune Deficiency (CVID). The immune system of patients with this disease is not capable of producing appropriate antibodies when a new virus or bacteria penetrates the body.
  • People with a mild antibody deficiency (lgG SPAD). These are patients with a mild antibody deficiency or reduced function in the production of antibodies.

In this research, whether or not the immune system responded to the COVID-19 vaccine was measured at different moments. Whether these patients remained protected over the course of time was also measured.

The VACOPID study revealed that patients with congenital immune disorders generally respond well to the COVID-19 vaccinations. For example, in a group of people with CVID, the majority (80%) responded positively to the vaccine. In this group, patients with a poor response often had several complications, such as autoimmune disease, malignant diseases, or autoinflammatory complications. In general, patients with a mild antibody deficiency produced as many antibodies after vaccination as a person without an immune disorder. In both groups, the T-cell response was the same as in healthy study subjects.

People with X-linked agammaglobulinaemia (XLA) responded less well to the COVID-19 vaccinations. They did not produce any antibodies. However, the T-cell response in this group was good. Further research into this is currently underway.

COBRA-KAI study: vaccination in the case of haematology patients

The immune system of haematology patients experiences problems at various levels. This is partly due to the actual disease, but also to the use of medication. Consequently, vaccinations work less well for these patients and therefore provide less protection against infectious diseases.

Different groups of haematology patients

During the webinar, it was explained that different groups of haematology patients exist. For example, there are patients who have undergone a haematopoietic stem cell transplantation and have had immunotherapy, chemotherapy or a donor transplantation, but also patients who use immunosuppressive drugs due to their disease. The COBRA-KAI study examined the vaccination response of different haematology patients with a higher risk that the vaccination would not work.

Vaccinated with Moderna

A total of 723 immunocompromised haematology patients took part in the study. All patients were vaccinated twice with the mRNA-1273 vaccine from Moderna. The response was measured after four weeks.

The majority of patients were protected after two vaccinations

About half of the patients produced sufficient antibodies after two vaccinations. Following a third vaccination, even more patients produced enough antibodies to protect against the coronavirus. A third vaccination is therefore recommended for this group of patients.

A small group of patients, such as patients with B-cell non-Hodgkin lymphoma or patients after CD19 CAR T-cell therapy, produced few, if any, antibodies after vaccination. Unfortunately, the vaccinations did not work for these groups. Follow-up research into this is underway.

Also read: response to COVID-19 vaccine in the case of renal disorders and cancer

What is the next step?

A large proportion of the patients with congenital immune disorders and haematology patients responded well to COVID-19 vaccinations, but the studies will continue. In both studies, the effect of a third vaccination will be (further) investigated. New results from the studies will be published on our webpage about research into the coronavirus.

> Lees hier in het Nederlands

Text: ZonMw and the researchers from the VACOPID and COBRA-KAI studies
Translation: Dave from NST Science
Video: Recording in ZOOM and Fixvision
Final editing: ZonMw


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