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Abstract Objective To compare “hybrid immunity” (prior COVID‐19 infection plus vaccination) and post‐vaccination immunity to SARS CoV‐2 in MS patients on different disease‐modifying therapies (DMTs) and to assess the impact of vaccine product and race/ethnicity on post‐vaccination immune responses. Methods Consecutive MS patients from NYU MS Care Center (New York, NY), aged 18–60, who completed primary COVID‐19 vaccination series ≥6 weeks previously were evaluated for SARS CoV‐2‐specific antibody responses with electro‐chemiluminescence and multiepitope bead‐based immunoassays and, in a subset, live virus immunofluorescence‐based microneutralization assay. SARS CoV‐2‐specific cellular responses were assessed with cellular stimulation TruCulture IFNγ and IL‐2 assay and, in a subset, with IFNγ and IL‐2 ELISpot assays. Multivariate analyses examined associations between immunologic responses and prior COVID‐19 infection while controlling for age, sex, DMT at vaccination, time‐to‐vaccine, and vaccine product. Results Between 6/01/2021 and 11/11/2021, 370 MS patients were recruited (mean age 40.6 years; 76% female; 53% non‐White; 22% with prior infection; common DMT classes: ocrelizumab 40%; natalizumab 15%, sphingosine‐1‐phosphate receptor modulators 13%; and no DMT 8%). Vaccine‐to‐collection time was 18.7 (±7.7) weeks and 95% of patients received mRNA vaccines. In multivariate analyses, patients with laboratory‐confirmed prior COVID‐19 infection had significantly increased antibody and cellular post‐vaccination responses compared to those without prior infection. Vaccine product and DMT class were independent predictors of antibody and cellular responses, while race/ethnicity was not. Interpretation Prior COVID‐19 infection is associated with enhanced antibody and cellular post‐vaccine responses independent of DMT class and vaccine type. There were no differences in immune responses across race/ethnic groups.

Background: School closures and distance learning have been extensively adopted to counter the COVID-19 pandemic. However, the contribution of school transmission to the spread of SARS-CoV-2 remains poorly quantified., Methods: We analyzed transmission patterns associated with 976 SARS-CoV-2 exposure events, involving 460 positive individuals, as identified in early 2021 through routine surveillance and an extensive screening conducted on students, school personnel, and their household members in a small Italian municipality. In addition to population screenings and contact-tracing operations, reactive closures of class and schools were implemented., Results: From the analysis of 152 clear infection episodes and 584 exposure events identified by epidemiological investigations, we estimated that approximately 50%, 21%, and 29% of SARS-CoV-2 transmission was associated with household, school, and community contacts, respectively. We found substantial transmission heterogeneities, with 20% positive individuals causing 75% to 80% of ascertained infection episodes. A higher proportion of infected individuals causing onward transmission was found among students (46.2% vs. 25%, on average), who also caused a markedly higher number of secondary cases (mean: 1.03 vs. 0.35). By reconstructing likely transmission chains from the entire set of exposures identified during contact-tracing operations, we found that clusters originated from students or school personnel were associated with a larger average cluster size (3.32 vs. 1.15) and a larger average number of generations in the transmission chain (1.56 vs. 1.17)., Conclusions: Uncontrolled SARS-CoV-2 transmission at school could disrupt the regular conduct of teaching activities, likely seeding the transmission into other settings, and increasing the burden on contact-tracing operations., (© 2022 The Authors. Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.)