Infection Risk and Vaccine Considerations in Multiple Sclerosis and Related Disorders

OBJECTIVE: This article provides an overview of infections, their association with specific immunotherapies, preventive strategies, diagnostic features, and management in patients with multiple sclerosis and related disorders. It reviews current guidelines and provides a practical approach to vaccinations in this population. LATEST DEVELOPMENTS: The spectrum of infections associated with the introduction of new immunotherapies is now being realized. For example, although fingolimod causes the most opportunistic infections, other drugs in this class have not been associated with similar infections; however, experience with them is also limited. Similarly, teriflunomide and dimethyl fumarate, previously considered relatively low risk, have now been associated with several infections. Evolving insights into vaccine responses in patients on immunotherapies have also helped inform discussions about their safety and utility. For example, although B-cell depletion with CD20-antibody therapies substantially reduces or even abrogates antibody responses to vaccines, the T-cell responses are quite robust, such that vaccination is still beneficial even if response cannot be documented with usual serologic testing. ESSENTIAL POINTS: Major advancements in the management of multiple sclerosis and related disorders with immunotherapies have also increased the risk for infections and raised questions about the need for and efficacy of vaccinations. Several types of infections can occur in individuals on immunotherapies; however, the vulnerability to infections depends on the specific class of treatment. Careful monitoring for infections and prompt investigations are necessary because atypical presentations and rapid progression may occur. Patient education is also key to early recognition of these infections. Immunotherapies can compromise the protective immune responses to vaccines; hence, timing the vaccines by giving them before starting or dosing of immunotherapies is important.