Anti-Spike IgG in multiple sclerosis patients after BNT162b2 vaccine: An exploratory case-control study in Italy

Background: Patients with neuroimmunological conditions such as multiple sclerosis (MS) often receive disease-modifying therapies (DMTs) or immunosuppressants which may reduce the response to vaccines. BNT162b2 (Pfizer-BioNTech) is the first COVID-19 vaccine authorized in Italy. Its clinical efficacy and serological response were not evaluated in MS patients receiving DMTs or immunosuppressants. This early multicenter study evaluated serological response to BNT162b2 and safety in these patients. Methods: From February 2021 we enrolled consecutive MS patients, treated with at least one DMT and all healthcare workers (HCWs), having received or being scheduled to receive the first dose of BNT162b2. Blood samples were collected after the second vaccine dose and analyzed to quantitatively detect the presence of anti-Spike antibodies. Serological response was compared to the one from a control population of HCWs, with neither neuroimmunological conditions nor receiving immunosuppressants. Patients receiving treatments associated with a possible reduced response (Under-scrutiny treatment group) were also compared to those undergoing other treatments. Anti-Spike levels were described as median and interquartile range (IQR). Comparisons were performed with Wilcoxon-Mann-Whitney test. Solicited and unsolicited adverse events (AEs) were collected. Results: 39 MS patients and a control population of 273 HCWs were included. One patient, under treatment with ocrelizumab, did not respond to BNT162b2, while all the remaining patients and all controls developed a serological response to the vaccine. Median anti-Spike levels were similar between patients (1471.0 BAU/ml; IQR 779.7 to 2357.0) and controls (1479.0 BAU/ml; IQR 813.1 to 2528.0) (p = 0.53). Patients included in the Under-scrutiny treatments group showed reduced anti-Spike levels (156.4 BAU/ml; IQR 33.4 to 559.1) compared to those receiving other treatments (1582.4 BAU/ml; IQR 1296.5 to 2219.0) (p = 0.001). Solicited AEs were all mild to moderate in severity, generally reported in the first days after vaccination, and resolved in the following days. Two MS patients reported a clinical relapse after the second vaccine dose. Conclusion: BNT162b2 induced a serological response in MS patients treated with DMTs similar to controls not receiving DMTs or immunosuppressants. Some treatments were associated with reduced levels of anti-Spike antibodies in patients. These observations have relevant implications for treated patients receiving BNT162b2 and the community.