(Geovana Albuquerque)

• A recent study investigated the effects of the COVID-19 vaccine in people with multiple sclerosis (MS) who take immunosuppressive medications.
• Researchers compared the immune responses to the vaccine of 20 participants with MS on anti-CD20 therapy against responses from volunteers without MS.
• Participants with MS on anti-CD20 therapy were able to mount an immunity response to the virus due to the strong impact of T-cell reactions — though not as strong a response as members of the control group.

A new study has found that people living with MS who take CD20 immunosuppressive medications are able to mount antibody responses to the COVID-19 messenger RNA (mRNA) vaccination. Their responses were not as strong as the study participants without MS, however.

Researchers from Penn Medicine found people undergoing anti-CD20 therapy — which depletes immune cells known as B cells — were able to mount a T-cell response to mRNA COVID-19 vaccines, the types offered by Pfizer and Moderna.

“The message from this study is clear — it is worthwhile for patients with MS receiving a CD20 treatment to get a COVID-19 vaccine, which will prevent severe illness,” said senior author Dr. E. John Wherry, ​​director of the Penn Institute for Immunology, in a news release about the study. “Based on this body of evidence, we urge patients with MS receiving a CD20 treatment to get a COVID-19 vaccine if they haven’t already.”

The Centers for Disease Control and Prevention have recommended booster shots of the Pfizer mRNA COVID-19 vaccine at least six months after a second dose for certain groups, including people ages 50 to 64 with underlying medical conditions that place them at high risk for severe COVID-19. A third dose of the Pfizer and Modern mRNA COVID-19 vaccinations may be recommended for people who did not develop an adequate immune response after the two-dose vaccination series.

Blocked B Cells Affect Vaccine Efficacy

People with multiple sclerosis sometimes take medications like Ocrevus (ocrelizumab), which blocks the protein CD20 on special immune cells known as B cells. B cells have been found to contribute to the development and advancement of MS.

B cells are responsible for making antibodies that help fight infection and give people immunity to viruses. Vaccines — like the ones for COVID-19 — activate B cells specifically to do this. However, if a person’s B cells are being blocked by anti-CD20 medications like Ocrevus, they may be unable to mount a typical antibody response after receiving the vaccine.

People with autoimmune diseases (such as MS) and those taking immunosuppressive medications to treat them did not participate in the clinical trials for the COVID-19 mRNA vaccines. Because of this, researchers wanted to study how anti-CD20 medications affect immunity to the COVID-19 mRNA vaccine.

Study Results: T Cells Step Up

The study followed 20 participants with MS who were treated with anti-CD20 therapy and 10 healthy volunteers. Blood samples were collected immediately before and after the first dose of vaccine, and again before and after the second dose. The researchers then analyzed the blood samples for antibodies and immune cells to see how well the participants’ immune systems responded to the COVID-19 vaccine.

All 10 of the healthy volunteers had a response to the vaccine and made antibodies. However, only 50 percent of the participants with MS made antibodies. This was most likely because the MS group had little to no B cells in their blood due to the Ocrevus treatment. However, another part of the immune system driven by special cells, known as T cells, responded well to the vaccine.