Background and Aims:

Since the worldwide launch of the SARS-CoV-2 vaccine campaign, several concerns apply on the response to vaccines in people with multiple sclerosis (pwMS) particularly those on high efficacy disease modifying therapies (DMTs).

We report preliminary data on humoral response to Covid-19 vaccine assessed on four pwMS treated with ocrelizumab (OCR) and compared to that measured in a sample of healthy subjects (HS) enrolled in a surveillance programme at our Clinic.

Methods:

We collected serum samples -at 0,14,21 days after the first dose and 7 days after the second dose of NT162b2-mRNA-Covid-19 vaccine of: i) 55 health-care workers, and ii) four relapsing MS patients on OCR, that were vaccinated with the same Covid-19 vaccine. All subjects did not have a history of Covid-19 infection. Sera were tested using the LIAISON®SARS-CoV-2 TrimericS-IgG assay (DiaSorin-S.p.A.), for the detection of IgG antibodies to SARS-CoV-2 spike protein. The IgG-titers were expressed in Binding Antibody Units (BAU).

Results:

Seven days after the second dose of NT162b2-mRNA-Covid-19 vaccine, all HS mounted a significant humoral response (geometric mean 2010.4 BAU/mL C.I.95%1512.7-2672), while all the four pwMS showed a very low response (range 4,9-175 BAU/mL).

Conclusions:

As expected and in agreement with previous data, we found a blunted humoral response to NT162b2-mRNA-vaccine in pwMS treated with OCR. Further data are urgently needed in order to confirm and expand these preliminary, yet significant results and to inform if there is any strategy to optimize the response to vaccines such as the count of circulating CD20 cells, time-elapsed since the last anti-CD20 drug administration.