A recent review published in the BSI’s official journal Clinical & Experimental Immunology looked to address health concerns about the influence of immunotherapies, used to treat some patients with autoimmune conditions, on their risk of infection with SARS-CoV-2.
Autoimmune diseases occur when our body’s immune response attacks our own healthy cells and tissues. The immune response is directed against antigens (proteins on cells) in our own organs and this drives persistent inflammation that disrupts the normal function of the tissue. Examples include multiple sclerosis (where the immune system attacks the cells making the myelin coating around nerves) and rheumatoid arthritis (where the immune system attacks the lining of the joints). Immunosuppressive treatments (immunotherapies) that block and reduce the immune response are effective and important in controlling some autoimmune diseases. This includes rituximab, oblinutuzumab, and ofatumumab that are used in cancer and rheumatoid arthritis, and ocrelizumab in multiple sclerosis.
Severe COVID-19 is associated with a reduced level of white blood cells and this has caused great concern for patients using immunotherapies who already have weakened immune systems. It is therefore important to understand how immunotherapies for autoimmune diseases influence susceptibility to infection with SARS-CoV-2, how they affect immunity to re-infection and the potential response to a vaccine for SARS-CoV-2 when it becomes available. Knowledge of how COVID-19 interacts with the body and immune system is increasing all the time and this new understanding may help guide treatment options for patients in the future.
B cell depleting therapies do not increase risk of getting severe COVID-19 for patients with autoimmune disease.
The authors looked at cases of COVID-19 in people with multiple sclerosis and rheumatoid arthritis who received immunotherapy that reduces the number of specialised white blood cells called B cells. Evidence shows that most of these people can clear SARS-CoV-2 infection without developing significant illness due to SARS-CoV-2. This suggests that B cells may not be an absolute requirement for recovery, and that low B cell numbers are unlikely to be a risk factor for major complications of COVID-19. This evidence suggests that it’s important for people with autoimmune diseases to continue their beneficial immunotherapy treatments during the pandemic.
B cell depleting therapies inhibit a vaccine response in patients with autoimmune disease.
An effective vaccine against SARS-CoV-2 will need to induce an immune response that generates protective neutralising antibodies, which are made by B cells. The reviewers looked at data from various clinical trials of vaccines which are currently on immunisation schedule, such as tetanus, pneumococcal and influenza. These trials involved people with a range of autoimmune diseases who take immunotherapies that reduce B cell numbers. The evidence shows that these people had a weaker immune response to all vaccines tested, making the vaccine less effective.
However, weeks or months after the person stops receiving the immunotherapy treatment, the B cell populations recover enough so that an antibody response does develop to some vaccines. This provides an opportunity to vaccinate and induce a better immune response. Importantly the disease-causing B cells remain depleted for a long time, so that disease will not return if treatment is delayed. This suggests that there is a perfectly timed “window for vaccination” for people on B cell depleting immunotherapies. As studies continue and we understand more about the types of immune response that potential SARS-CoV-2 vaccines generate, we will be better placed to assess how this patient group will respond.
Baker, D., Roberts, C.A.K., Pryce, G., Kang, A.S., Marta, M., Reyes, S., Schmierer, K., Giovannoni, G. and Amor, S. (2020), COVID‐19 vaccine‐readiness for anti‐CD20‐depleting therapy in autoimmune diseases. Clinical & Experimental Immunology. doi:10.1111/cei.13495
First published 16 July 2020
Summary author Erika Aquino, BSI Public Engagement Officer