Objectives: This study aimed to evaluate the effectiveness of the SARS-CoV-2 vaccination program in systemic sclerosis (SSc) patients treated by Autologous Hematopoietic Stem Cell Transplantation (AHSCT) compared to non-AHSCT SSc patients.
Methods: A French retrospective case-control study was conducted in SSc patients eligible for SARS-CoV-2 vaccination. AHSCT SSc (cases) were matched 1:1 with non-AHSCT SSc (controls) patients by age, sex, and disease duration. The primary endpoint was to assess the cumulative incidence of COVID-19 infection. Secondary objectives evaluated vaccination acceptance, the onset of severe adverse events after SARS-CoV-2 vaccination, the severity of COVID-19 infection and the serological response after vaccination or not.
Results: Seventy-two SSc patients (36 AHSCT 1:1 matched to 36 non-AHSCT, on age, sex, and disease duration on 1 January 2021) were included. The study showed a higher incidence of COVID-19 infection in AHSCT (p=0.007) versus non-AHSCT SSc patients, with respectively 11 out 36 cases and 2 out 36 controls contracting mild to moderate infections. The vaccine acceptance rate did not differ between AHSCT and non-AHSCT SSc patients, with respectively 5 out 36 cases and 3 out 36 controls who refused vaccination. No severe adverse event was reported after SARS-Cov-2 vaccination. Serological responses did not significantly differ between the two groups.
Conclusions: The incidence of COVID-19 infection was higher in AHSCT-SSc compared to non-AHSCT SSc patients, with no difference in vaccine acceptance rate. COVID-19 vaccination in AHSCT highly fragile patients appeared to provide substantial COVID-19 protection, as shown by their favourable clinical evolution and effective humoral response.