A plain language summary of the impact of vaccines against flu and chickenpox in people with multiple sclerosis treated with cladribine tablets

This is a summary of an article originally published in the Multiple Sclerosis Journal. Cladribine tablets (MAVENCLAD®) are an oral (taken by mouth) medication, approved for the treatment of people with relapsing forms of multiple sclerosis (MS, with episodes of new or worsening symptoms). They are administered for a maximum of 10 days per year, over a period of 2 years. Cladribine tablets work by temporarily reducing the number of lymphocytes, which are immune cells that help to fight off infections. Because of this, people with MS (also called PwMS) may have concerns about the effect of cladribine tablets on vaccines, as these work via immune cells to build protection against infection. A study called MAGNIFY-MS investigated how long it takes for cladribine tablets to begin to work in people with a type of MS called highly active relapsing MS. During the study, some participants received their usual vaccinations against flu (influenza) and against the chickenpox virus (also called varicella zoster virus) as part of their routine medical care. The MAGNIFY-MS study gave the researchers an opportunity to look at how cladribine tablets affect the way the flu and chickenpox virus vaccines work in the body. Cladribine tablets do not affect how well the body responds to flu and chickenpox vaccines. PwMS taking cladribine tablets who are vaccinated against chickenpox, flu or both can be protected against these diseases.