COVID-19 Vaccine Timing After Rituximab Can Decrease Hospitalization in MS

People with multiple sclerosis (MS) should receive messenger RNA (mRNA) SARS-CoV-2 vaccines or boosters more than 6 months after their last rituximab treatment to decrease the risk for COVID-19-related hospitalization, according to the findings of a retrospective cohort study published in JAMA Network Open.

Rituximab is a monoclonal antibody therapy that works by depleting B-cells. It is known to reduce humoral responses following SARS-CoV-2 vaccination, leaving individuals with MS who received these infusions more susceptible to severe COVID-19 infection, hospitalization, and potentially death.

Researchers in the United States conducted a retrospective cohort study from January 1, 2020 to February 15, 2022, using the Kaiser Permanente Southern California’s (KPSC’s) electronic health records to identify 3974 people with MS who had been vaccinated against COVID-19. Most patients (75%) were women with an estimated mean age of 55 years.

The researchers analyzed the influence of SARS-CoV-2 vaccination timing following rituximab treatment on the incidence of hospitalization and death related to COVID-19 in this patient population.

The researchers discovered that patients with MS treated with rituximab (n=1516) had a higher likelihood of hospitalization from COVID-19 infection compared with the 2458 individuals who were not treated with disease-modifying therapies (DMTs) or used DMTs other than rituximab (27 people vs. 7 people, respectively; adjusted odds ratio [aOR], 7.33; 95% CI, 3.05-17.63). No deaths occurred in either group.

The researchers noted a trend of decreasing hospitalizations in patients with MS when there was a bigger gap in the timing of SARS-CoV-2 vaccination following rituximab infusion. In particular, those who received SARS-CoV-2 vaccines or boosters more than 6 months following their last rituximab dose had reduced risk for COVID-19-related hospitalization (aOR, 0.22; 95% CI, 0.10-0.49).

The researchers confirmed that mRNA SARS-CoV-2 vaccines (aOR, 0.36; 95% CI, 0.15-0.90; P =.03) and booster vaccines (aOR, 0.31; 95% CI, 0.15-0.64; P =.002) demonstrated independent associations with decreased hospitalization risk from COVID-19 infection.

The findings revealed patients with MS treated with rituximab, when possible, should receive mRNA SARS-CoV-2 vaccines or boosters more than 6 months following their last rituximab infusion.

The researchers concluded that “The low risk of hospitalization for COVID-19 among mRNA-vaccinated individuals with MS receiving rituximab should not preclude rituximab use. Instead, expanding access to SARS-CoV-2 vaccines for individuals receiving rituximab therapy in low- and middle-income countries should be prioritized.”

Study limitations included the small number of hospitalizations and no deaths in the cohort group, requiring caution when interpreting effect size. Possible use of antivirals and a small number of patients in this cohort with more than 1 booster may have influenced results and made it difficult to ascertain the protective impact of these variables. Lastly, these findings may not necessarily apply to future strains or the Omicron variant, which was becoming more widespread by the conclusion of the study.