Long-Term Benefit of Perlingual Polybacterial Vaccines in Patients with Systemic Autoimmune Diseases and Active Immunosuppression

Introduction: We have previously shown that trained-immunity-based vaccines, namely TIbV, significantly reduce the rate of recurrent infections, both of the respiratory tract (RRTI) and urinary tract infections (RUTI) in SAD patients on disease-modifying drugs (DMARDs). Objective: We evaluated the frequency of RRTI and RUTI from 2018 to 2021 in those SAD patients that received TIbV until 2018. Secondarily, we evaluated the incidence and clinical course of COVID-19 in this cohort. Methods: A retrospective observational study was conducted in a cohort of SAD patients under active immunosuppression immunized with TIbV (MV130 for RRTI and MV140 for RUTI, respectively). Results: Forty-one SAD patients on active immunosuppression that were given TIbV up to 2018 were studied for RRTI and RUTI during the 2018–2021 period. Approximately half of the patients had no infections during 2018–2021 (51.2% no RUTI and 43.5% no RRTI at all). When we compared the 3-year period with the 1-year pre-TIbV, RRTI (1.61 ± 2.26 vs. 2.76 ± 2.57; p = 0.002) and RUTI (1.56 ± 2.12 vs. 2.69 ± 3.07; p = 0.010) episodes were still significantly lower. Six SAD patients (four RA; one SLE; one MCTD) with RNA-based vaccines were infected with SARS-CoV-2, with mild disease. Conclusions: Even though the beneficial protective effects against infections of TIbV progressively decreased, they remained low for up to 3 years, with significantly reduced infections compared to the year prior to vaccination, further supporting a long-term benefit of TIbV in this setting. Moreover, an absence of infections was observed in almost half of patients.