Is vaccination safe in MS?
Recent outbreaks of measles at Disneyland in California, other U.S. states, Quebec and Ontario are an indicator of the inadequate levels of immunization against common diseases, and the susceptibility of unvaccinated populations to epidemics. The interconnected world provides no quarantine.
The issue of vaccination is especially pertinent for people with multiple sclerosis. Preventing infections is important because a number of studies have found that they can increase a person’s likelihood of having a relapse (Correale and colleagues. Neurology 2006;67:652-659; Buljevac and colleagues. Brain 2002;125:952-960). However, because vaccination introduces a foreign substance (an antigen) into the body to induce an immune response, there is a concern that this may accidentally trigger a worsening of MS. In addition, the disease-modifying medications used to treat MS modify or suppress the immune response. So there is the further concern that vaccination may fail because the person’s body isn’t able to mount a sufficient immune response, or that vaccination will actually cause the disease.
There are two general rules of thumb when it comes to vaccination. The first is that vaccines containing live attenuated virus should generally be avoided. The second is that it’s best to have any vaccinations before starting MS treatment.
Let’s look at the different types of vaccines that are commonly used and whether they’re advisable in people with MS.
DTPT (diphtheria, tetanus, poliomyelitis and pertussis): Vaccination against these four illnesses is recommended for everyone, including people with MS (Loebermann and colleagues. Nat Rev Neurol 2012;8:143-151). The tetanus vaccine has been most studied in MS, and a meta-analysis found that people who had received a tetanus vaccination had a lower risk of relapses (Hernan and colleagues. Neurology 2006;67:212-215). There also doesn’t appear to be a higher risk of MS relapse after receiving the combined tetanus-diphtheria vaccine, according to the Vaccines in MS (VACCIMUS) Study (Confavreux and colleagues. N Engl J Med 2001;344:319-326; free full text at www.nejm.org/doi/pdf/10.1056/NEJM200102013440501). The polio vaccine typically uses inactivated virus and booster shots are recommended if travelling to a region where polio is endemic. There doesn’t appear to be an increased risk of relapse with the polio vaccine.
Influenza. The safety of influenza vaccines was extensively reviewed by the U.S. Institute of Medicine (free full report available at www.ncbi.nlm.nih.gov/books/n/nap10822/pdf/). The conclusion was there was no evidence to indicate that the flu vaccine worsened MS. Two recent studies also reported that the risk of relapse wasn’t increased after receiving the H1N1 vaccine (Farez and colleagues. Mult Scler 2012;18:254-256; Auriel and colleagues. J Neurol Sci 2012;314:102-103).
MMR (measles, mumps, rubella): Many studies over the years have noted that people with MS have an altered immune response to measles and rubella (Persson and colleagues. J Clin Virol 2014;61:107-112; Ahlgren and colleagues. J Neuroimmunol 2011;235:98-103). In fact, a characteristic of MS is high antibody production against measles, rubella and varicella (chickenpox) in cerebrospinal fluid, the so-called MRZ reaction. This reaction is found in over 80% of people with MS and is correlated with inflammatory lesion activity in the brain (Rosche and colleagues. PLoS One 2012;7:e28094).
MMR vaccination uses live attenuated virus so it should be avoided by people with MS, especially if they are taking an MS medication that suppresses the immune response (Esposito and colleagues. Vaccine 2014;32:5893-5900). People with MS who didn’t get measles, mumps and rubella in childhood who are exposed to one of these diseases should talk to their doctor about how best to protect themselves (e.g. passive immunization with immunoglobulins) (Loebermann 2012).
Varicella zoster virus: This causes chickenpox, after which the virus remains dormant in the body; if reactivated, it causes shingles. For people who have never been exposed to VZV, immunization is generally recommended before starting a course of an immunomodulatory therapy for MS. In particular, VZV antibody testing (to determine if there has been prior exposure to the virus) is advised for anyone planning to take Gilenya; if there has been no prior exposure, VZV vaccination is recommended at least one month before starting Gilenya. People with no prior VZV exposure should also consider vaccination before starting Lemtrada.
Yellow fever: One small study found that MS relapses became more frequent after this vaccine (Farez and colleagues. Arch Neurol 2011;68:1267-1271), so it is not recommended, especially in people with medication-related immune suppression.
Bacterial diseases. Vaccines against bacterial diseases, such as pneumonia, meningitis, typhoid fever and cholera, have generally not been studied in MS. One meta-analysis found no worsening of MS in people receiving the BCG vaccine for tuberculosis (Farez 2011). But this is an area that needs more research.
Because MS medications modulate or suppress the immune response, it is usually best to have any vaccinations done before starting on treatment. In Part 2 we’ll look at the impact of different MS medications on the effectiveness of vaccines.
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