- STUDY HIGHLIGHTS
- * Most vaccine reactions were mild and resolved quickly, with no MS-specific safety concerns identified.
- * Reactions peaked after the second dose and decreased with boosters, mirroring patterns in the general population.
- * Moderna recipients reported slightly more reactions than Pfizer recipients, though both vaccines were well tolerated.
As the COVID-19 pandemic unfolded, people in the MS community faced an urgent question: What will these new vaccines mean for me? To help answer it, participants in the iConquerMS people-powered research network stepped forward to share real-world information about their vaccination experiences. Their contributions formed the foundation of the original COVER-MS study—research that has now grown into a deeper, long-term look at how vaccine reactions unfold over time.
The new study, published in Multiple Sclerosis and Related Disorders, follows people with MS across multiple COVID-19 vaccine doses, from their first shot through subsequent boosters. Together, these findings paint a consistent and reassuring picture: while reactions to vaccination are common, they are typically mild, short-lived, and not associated with serious MS-related complications.
Across more than 1,000 participants, researchers observed that reactions such as injection-site pain, fatigue, headache, malaise, and chills were the most frequently reported—very similar to what is seen in the general population. Reaction rates tended to peak after the second dose, then decrease with later boosters. Most importantly, these reactions generally resolved quickly and did not lead to significant health problems.
The study also explored how vaccine type influenced experiences. Participants who received the mRNA-1273 (Moderna) vaccine reported slightly more reactions compared with those who received BNT162b2 (Pfizer-BioNTech). While individual factors like age, sex, and prior COVID-19 infection played a role in who reported reactions, none of these patterns suggested added safety concerns unique to people with MS.
Researchers additionally examined whether MS disease-modifying therapies affected vaccine reactions. Some treatments were associated with fewer reported reactions, but no evidence indicated that MS therapies made reactions more severe or more dangerous.
These findings strengthen what COVER-MS participants helped show early in the pandemic: people with MS tolerate COVID-19 vaccines well, and their experiences closely mirror those of the broader population. By continuing to share their lived experiences over multiple years, study participants have helped create one of the most detailed real-world pictures of vaccine safety in MS to date.
This work highlights the power of a community coming together to answer urgent questions—especially when evidence is limited and people need clear, trustworthy information to make decisions about their health.
iConquerMS is grateful to every participant who contributed their experiences. Your willingness to share continues to drive research that is grounded in real life and shaped by the people it is meant to serve. To learn more about the iConquerMS community and the research we power together, visit iConquerMS.org.