In general, the answer to that question is “yes,” but there are some details to take into consideration, according to Amit Bar-Or, MD, chief of the multiple sclerosis division at the University of Pennsylvania in Philadelphia. “There’s no reason to consider the flu shot as riskier for people with MS,” Dr. Bar-Or says. “Just having MS does not increase risk for adverse outcomes with the vaccine.” In fact, in guidelines updated in 2019, the American Academy of Neurology (AAN) recommended that people with MS get vaccinated against the flu annually, unless there’s a specific reason they can’t get it, such as an allergy to the vaccine. However, certain types of flu vaccine — there are more than a dozen formulated each year, according to the Centers for Disease Control and Prevention (CDC) — aren’t recommended for people on specific MS treatments, according to the National MS Society. This is because the vaccines may not be as effective at preventing the flu in people taking these drugs, the society says. Still, because there are many different flu vaccines available, you can find one that offers protection against the seasonal virus, Bar-Or notes. Here’s an overview of the types of flu vaccines and which ones may be impacted by your MS treatment. Antibodies are proteins created by your immune system that provide protection against infection with the virus that’s targeted by the vaccine. The vaccine’s formulation can vary from year to year based on what research suggests will be the most common flu variants during the winter season, the agency says. A few different processes are used to make flu vaccines: Inactivated (Killed) Flu Vaccines These are the injections most often called “flu shots,” the CDC says. The candidate vaccine viruses are grown in chicken eggs then inactivated (or killed) and purified. The inactivated flu vaccine therefore contains no live flu virus and cannot cause the flu. Some inactivated flu vaccines are made using mammalian cells to grow the flu virus instead of eggs. Live-Attenuated Influenza Vaccine This type of vaccine is made from weakened influenza viruses. These weakened viruses stimulate your immune system to create sufficient antibodies to fight off stronger forms of the virus. In the United States, live-attenuated flu vaccines are available in a nasal spray and are made in an egg-based process. Recombinant Flu Vaccines These vaccines aren’t made using candidate vaccine virus samples. Instead, they’re made synthetically, based on the RNA of naturally occurring flu viruses. They may be made in egg-based manufacturing processes, or using cell-based approaches, according to the CDC.
How MS Treatment May Impact Live and Live-Attenuated Flu Vaccine
Live and live-attenuated vaccines, including the live-attenuated flu vaccine, aren’t recommended for people with MS who take certain types disease-modifying therapies (DMTs), because the vaccines’ effectiveness may be reduced by these drugs, according to the National MS Society. However, this isn’t a reason to avoid vaccination altogether, Bar-Or says, if live and live-attenuated vaccines are your only option, as some protection is better than no protection. In some cases, however, DMTs may weaken the immune system, meaning those people injected with live or live-attenuated vaccines may be at risk for getting sick from the viruses the vaccines are designed to prevent, the society adds.
MS Drugs That May Reduce Live Vaccine Effectiveness
According to the AAN guidelines, research suggests that certain MS drugs, including dimethyl fumarate (Tecfidera), diroximel fumarate (Vumerity), fingolimod (Gilenya), glatiramer acetate (Copaxone, Glatopa), interferon beta-1a (Avonex, Rebif), interferon beta-1b (Betaseron, Extavia), mitoxantrone (Novantrone), natalizumab (Tysabri), and teriflunomide (Aubagio) may reduce the effectiveness of the live and live-attenuated flu vaccine. This doesn’t make the vaccine dangerous — it just means that it may not offer as much protection against the flu, Bar-Or says. Additionally, the reduction in vaccine protection caused by these medications may be small, so the shot will still offer significant protection against the flu virus, even while taking them, he says.
MS Drugs That May Weaken Your Immune System
However, the DMTs alemtuzumab (Lemtrada), cladribine (Mavenclad), ocrelizumab (Ocrevus), ozanimod (Zeposia), and siponimod (Mayzent) may weaken your immune system enough that live and live-attenuated vaccines, including the live-attenuated flu vaccine, shouldn’t be used or should only be used after taking precautions, the National MS Society advises. This is because even the weakened forms of the virus could make you sick. For this reason, people with MS taking alemtuzumab, or who have recently taken the drug, shouldn’t receive any live vaccines, including the flu vaccine, the society says. In addition, people taking ozanimod and siponimod shouldn’t get these vaccines. People with MS also shouldn’t start treatment with cladribine until four to six weeks after receiving a live or live-attenuated vaccine. And treatment with ocrelizumab shouldn’t be initiated until at least four weeks after you’ve received one of these vaccines — although it can be initiated two weeks after receiving an inactivated vaccine.
MS B Cell Therapies
B cell therapies used in the treatment of MS — including ocrelizumab, ofatumumab (Kesimpta), and rituximab (Rituxan) — may partially limit effectiveness of the flu vaccine, according to Bar-Or. He notes that these medications are designed to kill immune cells called B cells which, on one hand, are believed to play a role in the development of brain lesions in people with MS, but on the other hand, also serve as the cells that help the immune system make protective antibodies as part of the immune system’s ideal response to infection or vaccination. By leading to the death of B cells, these drugs can therefore make the vaccine less effective, at least as far as generating the antibody response is concerned. Bar-Or explains that “antibodies are generated through the activation of B cells, hence MS treatments that remove these cells result in a substantial decrease in the ability of the vaccine to generate antibodies.” “Since the effectiveness of vaccines is typically assessed based on their ability to generate an antibody response (such as anti-flu antibodies), it may appear that patients vaccinated while on B-cell-depleting therapies cannot mount any useful vaccine response,” he says. “However, assessing vaccine responses based only the antibody response in patients treated with B cell therapies likely underestimates the utility of the vaccines, since cellular immune responses to the vaccines (which are more important than antibody responses for many vaccines) are likely to be minimally impacted by the B cell therapies.”
The Best Flu Vaccines for People With MS
According to Bar-Or, all recombinant flu vaccines — those made synthetically, without use of the flu virus — are safe for people with MS, even those on DMTs. Similarly, inactivated vaccines are generally considered safe for people with MS, including those taking a disease-modifying therapy, according to the Cleveland Clinic. Other commonly used drugs in the treatment of MS — including the muscle relaxant baclofen, the stimulant modafinil (Provigil), and low-dose naltrexone — don’t affect the flu vaccine, or its safety, in any way, according to the National MS Society. Still, you should talk to your doctor about which flu vaccine is best for you, given the medications you take for your MS or for any other medical condition you may have. In addition, although it’s fine to get the vaccine at a doctor’s office, pharmacy, or clinic — just like anyone else — you should mention to whoever is administering the vaccine that you have MS to make sure you get the correct product, Bar-Or advises.
