Influenza Vaccine Efficacy 'Undiminished' in MS

Bruce Jancin

July 13, 2020

The efficacy of the influenza vaccine when given to patients with multiple sclerosis (MS) is similar to that in healthy controls, Jackie Nguyen reported at the virtual annual meeting of the Consortium of Multiple Sclerosis Centers (CMSC). She presented a systematic review and meta-analysis of nine published cohort studies including 417 MS patients and more than 500 healthy controls, all of whom received inactivated seasonal influenza vaccine.

The impetus for this project was a recognition that the great majority of the research on the impact of influenza vaccine in patients with MS has focused on safety and MS relapse rates. In contrast, the nine studies included in the meta-analysis contained data on influenza vaccine efficacy as reflected in the ability to mount an adequate immune response.

This was defined in standard fashion either by seroconversion, which required at least a fourfold increase in antibody titers following vaccination, or seroprotection, with a postvaccination antihemagglutination immunoglobulin G titer of at least 40. The analysis included patients with MS irrespective of disease duration or severity or treatment regimen, noted Ms. Nguyen, a third-year medical student at Nova Southeastern University College of Allopathic Medicine in Davie, Fla.

The researchers found that there was no significant difference between patients with MS and healthy controls in the rates of an adequate immune response for influenza H1N1, H3N2, or influenza B virus. "The vaccine should thus continue to be recommended for MS patients, as the data shows it to be efficacious," she said.

Her conclusion is consistent with guidance provided in the American Academy of Neurology’s 2019 practice guideline update on immunization in MS, highlighted elsewhere at CMSC 2020 in a presentation by Marijean Buhse, PhD, of Stony Brook University in New York.

The guideline, updated for the first time in 17 years, states that all MS patients should be advised to receive influenza vaccine annually: "With known risks of exacerbation and other morbidity with influenza infection and no identified risks of exacerbation with influenza vaccines, benefits of influenza vaccination outweigh the risks in most scenarios."

The exception involves the relatively few MS patients having a specific contraindication to the influenza vaccine, such as a previous severe reaction, noted Dr. Buhse, who wasn’t involved in developing the evidence-based guidelines.

The available evidence indicates that some but not all disease-modifying therapies for MS reduce the effectiveness of vaccination against influenza.

According to the guideline, "it is possible" that persons with MS being treated with glatiramer acetate have a reduced likelihood of seroprotection from influenza vaccine, a conclusion the guidelines committee drew with "low confidence in the evidence." Further, the guideline states that "it is probable" MS patients on fingolimod have a lower likelihood of obtaining seroprotection from influenza vaccine than patients not on the drug, with moderate confidence in the evidence.

Also, it is deemed probable that patients with MS who are taking mitoxantrone have a reduced likelihood of response to influenza vaccination, compared with healthy controls. But it is probable that patients with MS who are receiving interferon-beta have no diminution in the likelihood of seroprotection. According to the guideline, there is insufficient evidence to say whether patients with MS who are on natalizumab, teriflunomide, or methotrexate have a diminished response to influenza vaccination.

Dr. Buhse noted that rituximab is off-label therapy for MS, so there are no data available regarding the likelihood of seroprotection in response to influenza vaccination in that setting. However, rituximab profoundly decreases the immunogenicity of influenza and pneumococcal vaccines in rheumatoid arthritis patients. It is therefore recommended that inactivated influenza vaccine be given to patients with MS at least 2 weeks prior to starting rituximab or 6 months after the last dose in order to optimize the humoral results.

Ms. Nguyen reported having no financial conflicts regarding her presentation. Dr. Buhse reported having received honoraria from Genzyme and Biogen.

This article originally appeared on MDedge.com.

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