What are vaccines?
When the body is infected by a virus, bacterium or other invader, the immune system responds to fight it off. Once an infection is over, some of the antibodies developed to fight it remain in the immune system. This creates an ‘immune memory’, which means that should the same organism invade again, the body is already prepared to combat it. This is why diseases such as mumps or chicken pox usually only occur once.
Vaccination uses this idea to forewarn the immune system. A small amount or part of the organism that causes the infection is injected into the body so the immune system mounts a reaction against it to produce antibodies. When the person comes into contact with the real disease in the future, the immune system will recognise it and attack it with the antibodies, preventing infection.
There are two main types of vaccine: killed and live. Killed vaccines, such as the flu jab, use dead or inactivated organisms, which the body can still recognise as the disease causing invader but cannot cause the illness. Live, or attenuated, vaccines, such as MMR, contain organisms that have been weakened so they cannot cause disease in a healthy people. As a live vaccine is the closest thing to a natural infection it produces a strong immune response and often gives lifelong protection.
Vaccines and the risk of developing MS?
In the past there has been concern over the potential effect of vaccinations on the risk of people developing MS. Research has failed to find evidence to support these concerns.
In 2011, researchers reviewed previous studies on a range of vaccines. They found that the risk of developing MS remained unchanged after vaccinations for BCG (which causes tuberculosis), hepatitis B, influenza, MMR (measles, mumps, rubella), polio and typhoid fever. Their results suggested that diphtheria and tetanus vaccination may even be associated with a decreased risk of MS.
A US study from 2014 looked at the vaccination records of more than 4,500 people, with particular interest in hepatitis B and the human papillomavirus (HPV) vaccines. This found no increased risk of MS in the three years following vaccination.
A Scandinavian study published in January studied the records of almost 4 million women and found that the risk of MS was no greater in those who had had the HPV vaccination, which protects against cervical cancer, than in those who had not.
Do MS drugs affect how vaccines work?
A review of previous research looked at how the disease modifying drugs affected the effectiveness of the flu vaccine. For people on one of the four beta interferon drugs (Avonex, Betaferon, Extavia and Rebif) or teriflunomide (Aubagio) the vaccination protected them against flu. The evidence for natalizumab (Tysabri) was mixed with differing results from two trials. Small studies of glatiramer acetate (Copaxone) and fingolimod (Gilenya) suggested that the vaccine was less effective, though the numbers of people involved was too low to be certain. A more recent study of fingolimod found that almost half were protected by the flu vaccine compared to three quarters of people not taking the drug.
Should people with MS have vaccinations?
While there are rare complications with vaccinations, the risk of these occurring are the same for people with MS as in the general population. On the other hand, there is strong evidence that infections can worsen MS symptoms and increase the risk of a relapse.
There has been controversy around the use of the hepatitis B vaccine with occasional case reports of people experiencing symptoms or a relapse after the injection. This risk has not been seen in larger scale studies, which suggests that hepatitis B vaccination is probably safe for most people with MS.
In the vast majority of cases the benefits of vaccination greatly outweigh any risk and people with MS are encouraged to have any recommended vaccinations, such as the annual flu jab.
There are a few exceptions to this guidance. People who are experiencing a relapse may be advised to wait until this has passed before having a vaccination. Similarly, someone with an infection may need to wait until this has cleared up.
As there is a risk that a live vaccine may still cause symptoms or develop into the disease, these are generally not recommended for people with MS, particularly those on drugs that supress the immune system such as natalizumab (Tysabri) or steroids. If you are not sure if the vaccination you are being offered is live or not, talk to your doctor or your MS nurse.
Farez MF, Correale J.
Immunizations and risk of multiple sclerosis: systematic review and meta-analysis.
Journal of Neurology 2011;258(7):1197-1206.
Farez MF, Correale J.
Yellow fever vaccination and increased relapse rate in travelers with multiple sclerosis.
Archives of Neurology 2011;68(10):1267-1271
Langer-Gould A, et al.
Vaccines and the risk of multiple sclerosis and other central nervous system demyelinating diseases.
JAMA Neurology 2014;71(12):1506-1513.
Scheller NM, et al.
Quadrivalent HPV Vaccination and Risk of Multiple Sclerosis and Other Demyelinating Diseases of the Central Nervous System
Pellegrino P, Carnovale C, Perrone V, et al.
Efficacy of vaccination against influenza in patients with multiple sclerosis: The role of concomitant therapies.
Kappos L, et al.
Randomized trial of vaccination in fingolimod-treated patients with multiple sclerosis.
Coustans M, et al.
Demyelinating disease and hepatitis B vaccination: survey of 735 patients seen at an MS clinic.
Confavreaux C, et al.
Vaccinations and the risk of relapse in multiple sclerosis.
New England Journal of Medicine 2001;344:319-326.