Efficacy of vaccination against influenza in patients with MS

Treatment, therapies and management:
People with MS are exposed to an increased risk of infection from communicable diseases, which may lead to severe disease relapses. Vaccination represents a mainstay in the prevention of communicable infectious diseases among patients with MS. Vaccination, however, in MS as in many other diseases, raises concerns of safety and efficacy.
Several studies have analysed the issue of vaccination of MS patients. These studies, however, deal mostly with safety-related issues documenting that most vaccines have been proven to be safe in MS patients and that vaccination is not associated with an increased risk of relapses. The authors reviewed the literature and assessed the effects of the therapy for MS on vaccine efficacy. They focused on the vaccine against influenza as information on other vaccines is limited. Efficacy responses to vaccines may be measured with several tests.

In this review the authors chose in the majority of the cases the ones suggested by the EMA guidelines. As many of the MS drugs do not share a common mechanism of action, the authors explored the efficacy of vaccination in each of them separately. The results indicate that the influenza vaccine is effective in MS untreated patients and several studies concurred indicating a comparable efficacy of the influenza vaccine between MS patients treated with beta-interferon and healthy controls. Among MS patients treated with glatiramer acetate, the influenza vaccine may determine a grade of protection lower than in healthy individuals. Some data suggest that mitoxantrone can interfere with influenza vaccine efficacy as well. The efficacy of influenza vaccine in patients treated with natalizumab was evaluated in two studies that yielded conflicting results: one reporting a lower rate of protection in patients treated with natalizuamab, the other no significant differences. These conflicting results may be attributed to the relative small sample size of these studies.

Further analyses are therefore required to solve this issue. In fingolimod-treated patients, the data showed that patients may mount a vaccine-specific adaptive immune response which is comparable to the response observed in healthy controls. These observations may indicate that the efficacy response to the influenza vaccine is not impaired by fingolimod treatment.
To date, only one study, the Teriflunomide and Vaccination (TERIVA), has analysed the effect of this drug on influenza vaccine efficacy. The results of the TERIVA studies demonstrate that patients treated with teriflunomide are able to mount effective immune responses to seasonal influenza vaccination. An assessment of the efficacy of influenza vaccine in patients treated with alemtuzumab, rituximab and daclizumab have not yet been reported, and the available information is on other vaccines. All these data showed that vaccination impacts on patients afflicted by MS depending on their therapeutic regimen. Untreated patients or patients in treatment with interferon beta appear capable of mounting a normal vaccine response. Likewise, patients treated with fingolimod, teriflunomide and alemtuzumab may be able to mount a proper response to vaccination. These results, however, require further validation, as they arise from single or few studies. Likewise, the analysis of data on natalizumab did not yield concordant evidence about the efficacy of vaccination in patients treated with this drug, and analyses on larger samples are needed to confirm this datum. Patients in treatment with mitoxantrone and glatiramer acetate appear to have a poor response to the vaccine against influenza and this may suggest the opportunity of a second dose of vaccine; further studies are however required to assess the real clinical benefit of this option.

For other drugs, such as rituximab or daclizumab, there is not enough evidence from patients affected by MS. The extension of results from other pathological setting warns about a possible lower response to vaccination. These observations, however, need to be confirmed by specific analyses in the MS setting.

Pellegrino P, Carnovale C
Source: Vaccine. 2014 Jul 4. pii: S0264-410X(14)00869-X. doi: 10.1016/j.vaccine.2014.06.068. [Epub ahead of print]
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