Multiple sclerosis (MS) is a chronic neurological condition where the immune system mistakenly attacks the protective covering of nerve fibers, causing communication problems between the brain and the rest of the body. To manage MS, many patients use disease-modifying therapies (DMTs), which alter or suppress the immune system to reduce the frequency and severity of relapses and slow disease progression. However, because these treatments affect the immune system, a common concern is whether MS drugs influence the effectiveness of vaccines, especially important vaccines like those for COVID-19.
Vaccines work by stimulating the immune system to recognize and fight specific pathogens, often by prompting the body to produce antibodies against parts of the virus or bacteria, such as the spike protein in the case of COVID-19. For people with MS on immune-modulating or immune-suppressing drugs, the question is whether their immune systems can mount a strong enough response to vaccination to provide protection.
Research shows that the impact of MS drugs on vaccine effectiveness varies depending on the type of therapy. Some MS treatments, particularly those that strongly suppress the immune system, can reduce the body’s ability to produce antibodies after vaccination. For example, therapies like anti-CD20 monoclonal antibodies (such as ocrelizumab and rituximab) and sphingosine-1-phosphate (S1P) receptor modulators (like fingolimod) are known to attenuate the humoral immune response. This means patients on these drugs often have lower levels of protective antibodies after receiving vaccines compared to those not on such treatments.
Despite this, studies have found that even patients on these stronger immune-suppressing therapies can still generate some immune response after vaccination, especially after multiple doses or booster shots. For instance, a fourth COVID-19 vaccine dose has been shown to significantly improve antibody levels and broaden protection against various virus variants in people with MS, including those on potent immune-suppressing drugs. Boosters can increase protection by two to four times and reduce the number of individuals with no detectable protective antibodies by up to two-thirds.
On the other hand, patients on MS treatments that are less immunosuppressive, such as cladribine or other lower-efficacy DMTs, tend to have stronger initial vaccine responses and still benefit from booster doses. This suggests that while some MS drugs may dampen vaccine effectiveness, vaccination remains beneficial across all treatment groups.
It’s also important to note that vaccines used for people with MS, including inactivated vaccines and mRNA vaccines like those for COVID-19, are considered safe and are recommended. The immune response to vaccines includes both antibody production (humoral immunity) and activation of immune cells (cell-mediated immunity), and even if antibody levels are lower, cell-mediated responses may still provide meaningful protection.
Some recent research has explored adjusting the dosing schedules of certain MS drugs, such as anti-CD20 therapies, to balance disease control with immune system function. Less frequent dosing has shown promising results in maintaining disease stability without increasing relapse risk, which might also help preserve better vaccine responses, though more studies are needed to confirm this.
In practical terms, people with MS are encouraged to receive recommended vaccinations, including COVID-19 boosters, regardless of their treatment regimen. Monitoring antibody levels and immune status can help guide personalized vaccination schedules and additional protective measures. Some patients may also receive supplemental therapies, like monoclonal antibodies designed to provide passive immunity, to enhance protection if their vaccine response is weak.
Overall, while certain MS drugs can reduce vaccine effectiveness by dampening the immune response, vaccination remains a critical and effective tool for protecting people with MS from infections. Booster doses improve immune protection even in those on strong immune-suppressing therapies, and ongoing research continues to optimize treatment and vaccination strategies to ensure the best possible outcomes for people living with MS.
