Inactivated Vaccines Found Safe and Effective for MS Patients Treated with Natalizumab


Highly effective therapies for treating multiple sclerosis (MS) are becoming increasingly available and widely used.

However, some of these treatments, including anti-CD20 monoclonal antibodies, can increase the risk of infections, activate latent viruses, or worsen existing infections. Vaccination has been considered a viable strategy for infection risk reduction, but coordinating vaccination schedules with MS therapy initiation can be a delicate dance.

Immunosuppressants, such as anti-CD20 therapies, can suppress the immunogenicity of some vaccines. On the other hand, initiating anti-CD20 treatments without first administering appropriate immunizations can increase the risk of serious infections in people with MS.

As a result, clinicians typically tend to delay the initiation of high-efficacy therapies in people with MS until the patient has completed their vaccination schedule. Current guidelines recommend waiting at least two weeks after immunization with inactivated vaccines to begin treatment with highly effective therapies.

Unfortunately, some vaccine series, such as that for the hepatitis B virus (HBV), can require up to six months to complete the schedule. A long wait for treatment initiation could result in worse outcomes and disease progression, particularly in people with highly active MS.

A group of researchers led by René Carvajal, M.D., from the department of neurology-neuroimmunology at the Multiple Sclerosis Centre of Catalonia (Cemcat) in Barcelona, Spain, investigated the safety and immunogenicity of inactivated vaccines administered to patients with MS while receiving treatment with natalizumab, a highly effective MS therapy.

The study results were published last month in JAMA Network Open.

Natalizumab is an integrin receptor antagonist indicated for the treatment of relapsing forms of MS and Crohn’s disease. It is marketed under the brand name Tysabri (Biogen) as well as the biosimilar Tyruko (Sandoz).

Carvajal and his colleagues followed patients with MS from a study center in Spain from September 2016 through February 2022. They included adults who had received at least one of the following immunizations while receiving treatment with natalizumab: hepatitis A virus (HAV), HBV, or COVID-19. The researchers analyzed patient records during the 12 months before and the 12 months following vaccination.

The researchers evaluated vaccine antibody levels before and after vaccination. They also compared annualized relapse rates (ARR), expanded disability status scale (EDSS) scores, and new T2 lesion counts during the 12 months preceding vaccination and the 12 months post-vaccination.

Per current guidelines, John Cunningham virus (JCV) index levels were assessed before and during natalizumab treatment. Natalizumab carries a boxed warning for the risk of progressive multifocal leukoencephalopathy (PML), a potentially fatal viral infection of the brain. The presence of anti-JCV antibodies correlates with an increased risk of developing PML.

The investigators found an overall seroprotection rate of 93% (92% for HAV, 93% for HBV, and 100% for COVID-19). No differences in EDSS scores or new T2 lesions between the pre- and postvaccination periods were noted, and ARR improved. Although 65% of patients had a positive JCV index, none developed PML. After completing their vaccination schedule, 79% of participants with a positive JCV test transitioned to anti-CD20 therapy.

Carvajal and his colleagues concluded that their study findings suggest that immunization with inactivated vaccines in patients with MS receiving natalizumab treatment is safe and immunogenic. They indicate that patients with highly active MS who may need prompt initiation of highly effective therapy and immunization could benefit from natalizumab treatment while completing their vaccination schedules.

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