• People with multiple sclerosis (MS) who’ve received COVID-19 vaccinations and take ocrelizumab (Ocrevus) or fingolimod (Gilenya) are more likely to develop breakthrough COVID-19 than those those who take other types of disease-modifying therapies (DMTs), according to a new study.
• Vaccinated people with MS who take ocrelizumab also have a higher risk of developing severe COVID-19 and requiring hospitalization compared to their counterparts who take other DMTs.
• Overall, people with MS who are fully vaccinated still have a lower risk of developing severe COVID-19 and of requiring hospitalization if they become infected compared to those who aren’t vaccinated.

People living with MS who take ocrelizumab or fingolimod may have a higher risk of developing breakthrough COVID-19 infections, compared to those taking other types of disease-modifying therapies. Breakthrough infections refer to instances where people who’ve been fully vaccinated against COVID-19 still develop an infection.

Even though ocrelizumab and fingolimod reduced COVID-19 vaccine effectiveness compared to other DMTs, the risk of developing COVID-19 was higher in unvaccinated people with MS than those who were fully vaccinated — regardless of which DMT they were taking.

The study also found that people taking ocrelizumab who did develop breakthrough cases of COVID-19 were far more likely to require hospitalization than vaccinated people taking other types of DMTs. For those individuals, the risk of hospitalization following a breakthrough case was far lower than for their unvaccinated counterparts.

The study, published in June in Multiple Sclerosis Journal, adds important information to what is known about how DMTs affect COVID-19 vaccine effectiveness. Notably, breakthrough cases of COVID-19 have increased since the study was conducted as new variants of SARS-CoV-2, the virus that causes COVID-19, have emerged.

Nevertheless, health agencies and experts — including the Centers for Disease Control and Prevention (CDC) — report that people who are fully vaccinated are less likely to experience severe symptoms if they get a breakthrough infection, compared to people who aren’t vaccinated who contract the virus.

How Do DMTs Affect COVID-19 Vaccine Effectiveness?

Previous studies have shown that people who take DMTs develop lower antibody responses to messenger RNA (mRNA) COVID-19 vaccines compared to people who don’t take any DMTs. This means that mRNA COVID-19 vaccines from the likes of Pfizer and Moderna are still effective in people with MS who are taking DMTs — but their immune response is weaker than that of people without MS. However, scientists are still investigating how the weakened immune response affects COVID-19 outcomes in people with MS.

The new study was designed to evaluate whether the type of DMT a person took mattered in terms of their risk of a COVID-19 breakthrough infection.

MyMSTeam members have shared their questions and experiences with COVID-19 and vaccinations: “I had my first COVID-19 vaccine in February 2021 and my second in March 2021. I got COVID-19 in September 2021. I truly believe having received the two vaccines made the symptoms less severe than if I had not gotten the shots.”

Another member shared, “I had three vaccines and no adverse reactions to any of them (barely a sore arm), so I will continue to side with science.”

COVID-19 Severity Was Higher in People With MS Taking Ocrelizumab

For the study, researchers analyzed data about 19,641 people in Italy living with MS. The people enrolled in the study were fully vaccinated, meaning they received either two or three doses of Pfizer or Moderna mRNA vaccine or one vaccine dose after COVID-19 infection. Researchers also looked at which DMTs participants were taking.

Researchers found that 137 participants developed breakthrough COVID-19 infections during the study period, spanning March 1, 2021, through Dec. 24, 2021. For these individuals, researchers looked at how severe their infection was and how many required hospitalization.

Ultimately, researchers found that the chances of breakthrough infections were generally low for all people who’d been vaccinated and were taking DMTs. For those taking DMTs other than ocrelizumab or fingolimod, the rate was less than 1 percent. For those on fingolimod, the rate was 1.62 percent. Participants taking ocrelizumab had a breakthrough rate of 2 percent.

In other words, participants on ocrelizumab were 3.55 times more likely to have a breakthrough infection and people on fingolimod were 2.65 times more likely to have a breakthrough infection.

Additionally, researchers found that among participants who were taking ocrelizumab, the risk of severe COVID-19 infection requiring hospitalization was 16.7 percent. For people taking ocrelizumab who had not been vaccinated, the hospitalization rate had been 19.4 percent.

By comparison, vaccinated people taking all other DMTs had a hospitalization rate of 3.9 percent, significantly lower than the hospitalization rate for unvaccinated people taking DMTs, which had been 11.9 percent.

Vaccines Reduce Infections and Hospitalization Risks

This study adds detail to what is known about how different DMTs affect COVID-19 vaccine effectiveness. Vaccines help reduce breakthrough infections and severe COVID-19 symptoms for people with MS, but effectiveness can be lower in those taking ocrelizumab and fingolimod compared to other DMTs.

The CDC currently recommends:

• COVID-19 vaccines for everyone 6 months and older
• Boosters for everyone 5 years and older, if eligible
• Two boosters for adults age 50 and over and some people 12 and older who are moderately or severely immunocompromised

The National Multiple Sclerosis Society also encourages people with MS to get vaccinated as soon as possible. “Vaccination against COVID-19 is critical for your safety, for public safety, and, especially, for the safety of the most vulnerable among us. The risks of COVID-19 far outweigh any potential risks from the vaccines, but there may be special considerations for those living with multiple sclerosis,” the nonprofit notes on its website.

If you are taking a DMT and have questions about how it could affect the effectiveness of your COVID-19 vaccination or booster, reach out to your medical provider.

Find Your Team

Connect with others on MyMSTeam, the social support network for those living with MS and their loved ones. More than 191,000 members come together to ask questions, give advice, and share their stories with others who understand.

Are you vaccinated against COVID-19? Do you believe it’s helped protect you from COVID-19 infection or lessened the severity of breakthrough infections? Share your insights in the comments below, or start a conversation by posting on your Activities page.