Real-World Experience on the Use of COVID-19 Vaccination in Multiple Sclerosis Patients Treated with Cladribine Tablets Participating in the ADVEVA® Patient Support Program within the Gulf and Latin American Regions

BACKGROUND: National Multiple Sclerosis Society and other international guidelines suggest that full COVID-19 vaccination status should be completed two to four weeks before starting Year 2 of treatment with cladribine tablets (CladT). CladT is administered twice over two years, Year 1 and Year 2. There is a special interest in real-world evidence on whether vaccination status may affect initiation of CladT treatment in Year 2. The objective of this analysis was to describe the proportion of patients treated with CladT who received COVID-19 vaccination, and whether this influenced the timing of initiating treatment with CladT in Year 2. MATERIAL(S) AND METHOD(S): A vaccination questionnaire–based survey was sent to patients treated with CladT who were enrolled in the ADVEVA® patient support program (PSP), upon their consent. The survey was carried out in the Gulf region (GULF) from Jun 2021 to Sept 2021, and in the Latin American region (LATAM) from Jan 2022 to Mar 2022. Demographics, COVID-19 vaccination status, type of vaccine(s), number of doses received, and dates of vaccination were collected. In each region, patient data from the survey were linked to data routinely collected by the PSP, with cut-off dates as mentioned. Fully vaccinated status was defined as having received 2 doses of mRNA vaccine, 1 dose of Johnson & Johnson vaccine or other vaccines approved by the World Health Organization, plus 14 days. Descriptive analyses were performed and time to Year 2 treatment initiation among those with at least 18 months’ follow-up was estimated by vaccination status. RESULT(S): The survey participation rate in GULF was 87% (91 out of 105) and 19% in LATAM (152 out of 789). In total, 62 (68%) patients in GULF and 144 (95%) in LATAM were fully vaccinated against COVID-19. In both regions, among those with at least 18 months’ follow-up (GULF, n=59; LATAM, n=81), all patients initiated Year 2 of treatment with CladT, regardless of vaccination status. In GULF, the mean (standard deviation) time to treatment initiation in Year 2 was 13.8(1.6) months among fully vaccinated patients (44%) and 13.3(3.5) months among those not fully vaccinated (21%). In LATAM, the mean time was 12.8(1.4) months among those fully vaccinated (52%) and 12.4(0.02) months among those not fully vaccinated (1.3%). In each region, only 1 patient initiated Year 2 treatment after at least 18 months from the start of Year 1. CONCLUSION(S): Most patients were fully vaccinated against COVID-19 in GULF and in LATAM, which was consistent with vaccination coverage and guidelines in both regions. In LATAM, low participation rates might lead to selection bias which limits interpretation of results. In these regions, with limited data, COVID-19 vaccination status did not appear to alter the time of treatment initiation with CladT in Year 2. Almost all patients followed the label recommendations in terms of timing of Year 2 treatment initiation.