Autoimmune disease treatments create a paradox: They suppress the immune system to stop it from attacking healthy tissue. But they also leave people vulnerable to other germs and infections — and can impact how well vaccines work.

This issue of vaccine efficacy has taken center stage in light of the pandemic. A BRI team led by Estelle Bettelli, PhD, and Yevgeniy Yuzefpolskiy, PhD, recently made key findings about how three different medicines for multiple sclerosis (MS) impact response to COVID-19 vaccines.

“Knowing if and how these individuals respond to SARS-CoV-2 vaccines — and if part of their immune response is missing — will help us learn how to improve protection,” Dr. Bettelli says.

Impact on Vaccine Protection

For this study, people taking therapies that slow down the immune system to treat MS had their blood drawn before and after receiving the Pfizer or Moderna COVID-19 vaccine. The research team compared these blood samples to those of people who don’t have MS. Specifically, they looked at how common MS therapies impact B and T cells, which help your body recognize and attack harmful invaders. They learned:

• Anti-CD20 therapies, which eliminate several types of B cells, led to the absence of antibodies against SARS-CoV-2, the virus responsible for COVID-19. T cell response was still strong.

• Dimethyl fumarate therapy, which slows down T cells, led to a significantly lower T cell response, but only a small decrease in antibodies. Three months after the vaccine, antibody levels were comparable to those of the general population.

• Fingolimod therapy, which keeps T cells from reaching the circulation, led to a weaker response in both B cells and T cells.

“We were pleased to know that at least part of the response was still strong in many patients,” Dr. Yuzefpolskiy says. “We still need to learn exactly how much this partial response protects people. We hope we can build on these findings and support future vaccine efforts so everyone — especially those most vulnerable to complications — can get the best protection.”