New Data Presented at ACTRIMS Forum 2021 Indicate MAVENCLAD®-treated RMS Patients Mount Protective Antibody Response to Common Vaccines

Darmstadt, Germany (ots/PRNewswire) - MAGNIFY-MS retrospective analysis
demonstrates patients develop protective antibody levels for at least six months
following seasonal influenza and varicella zoster vaccines, irrespective of
vaccine timing relative to MAVENCLAD dosing

Initial findings from the CLOCK-MS vaccine sub-study show protective influenza
antibody levels at four weeks post-vaccination in MS patients taking MAVENCLAD

In both studies, protective antibody levels were maintained or increased
independent of lymphocyte counts

Not intended for UK and U.S. based media

Merck, a leading science and technology company, today announced the
presentation of a new analysis from the MAGNIFY-MS study on MAVENCLAD®
(cladribine tablets) in patients with relapsing multiple sclerosis (RMS) at the
Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS)
Forum 2021, being held virtually 25-27 February 2021. The data indicate that RMS
patients receiving MAVENCLAD are able to mount a response to seasonal influenza
and varicella zoster vaccination.

"Understanding vaccine efficacy in MS patients is particularly important in the
face of the current pandemic and the growing availability of COVID-19 vaccines,"
said Klaus Schmierer, Professor of Neurology at Queen Mary University of London
and The Royal London Hospital, UK. "Whilst this new information is based on a
small cohort of patients receiving influenza and varicella zoster vaccines, it
provides physicians with preliminary evidence that patients taking MAVENCLAD are
able to mount and maintain effective vaccine responses."

The retrospective analysis was conducted to evaluate the protective antibody
response to seasonal influenza (n=12) and varicella zoster virus (VZV)
vaccination (n=3) in patients treated with MAVENCLAD. Blood samples taken before
and after vaccination were examined. In patients who received the seasonal
influenza vaccine, protective antibody levels were maintained or increased for
at least six months independent of lymphocyte counts measured at the time of
vaccination in year 1 or 2 of MAVENCLAD treatment. In patients who received the
VZV vaccine before year 1 initiation of MAVENCLAD, protective VZV antibody
levels were maintained over six months post-initiation with MAVENCLAD, despite
lymphocyte depletion. These results were consistent irrespective of when the
patients received the vaccine relative to their MAVENCLAD treatment.

In the CLOCK-MS vaccine sub-study analysis, three relapsing remitting multiple
sclerosis (RRMS) patients had received at least one dose of MAVENCLAD prior to
receiving an influenza vaccine. Protective antibody levels were increased at