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BackgroundAs SARS-CoV-2 vaccination coverage increases in the United States (US), there is a need to understand the real-world effectiveness against severe Covid-19 and among people at increased risk for poor outcomes. MethodsIn a multicenter case-control analysis of US adults hospitalized March 11 - May 5, 2021, we evaluated vaccine effectiveness to prevent Covid-19 hospitalizations by comparing odds of prior vaccination with an mRNA vaccine (Pfizer-BioNTech or Moderna) between cases hospitalized with Covid-19 and hospital-based controls who tested negative for SARS-CoV-2. ResultsAmong 1210 participants, median age was 58 years, 22.8% were Black, 13.8% were Hispanic, and 20.6% had immunosuppression. SARS-CoV-2 lineage B.1.1.7 was most common variant (59.7% of sequenced viruses). Full vaccination (receipt of two vaccine doses [≥]14 days before illness onset) had been received by 45/590 (7.6%) cases and 215/620 (34.7%) controls. Overall vaccine effectiveness was 86.9% (95% CI: 80.4 to 91.2%). Vaccine effectiveness was similar for Pfizer-BioNTech and Moderna vaccines, and highest in adults aged 18-49 years (97.3%; 95% CI: 78.9 to 99.7%). Among 45 patients with vaccine-breakthrough Covid hospitalizations, 44 (97.8%) were [≥]50 years old and 20 (44.4%) had immunosuppression. Vaccine effectiveness was lower among patients with immunosuppression (59.2%; 95% CI: 11.9 to 81.1%) than without immunosuppression (91.3%; 95% CI: 85.5 to 94.7%). ConclusionDuring March-May 2021, SARS-CoV-2 mRNA vaccines were highly effective for preventing Covid-19 hospitalizations among US adults. SARS-CoV-2 vaccination was beneficial for patients with immunosuppression, but effectiveness was lower in the immunosuppressed population.
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BackgroundThere is an ongoing critical need to improve therapeutic strategies for COVID-19 pneumonia, particularly in the most severely affected patients. Adult mesenchymal stem cell (MSC) infusions have the potential to benefit critically ill patients with acute respiratory syndrome SARS-COV-2 infection, but clinical data supporting efficacy are lacking. MethodsWe conducted a case-control study of critically ill patients with laboratory-confirmed COVID-19, severe acute respiratory distress syndrome (ARDS). To evaluate clinical responsiveness in the most critically ill patient we examined outcomes in a sub-group of those requiring extracorporeal membrane oxygenation (ECMO) support. Patients (n=9) were administered with up to 3 infusions of intravenous (IV) MSCs and compared to a local ECMO control group (n=31). The primary outcome was safety, and the secondary outcomes were all-cause mortality (or rate of hospital discharge), cytokine levels, and viral clearance. FindingsMSC infusions (12 patients) were well tolerated and no side effects occurred. Of ECMO patients receiving MSC infusions, 2 out of 9 died (22.2%; 95%CI: 2.8%, 60.0%) compared with a mortality of 15 of 31 (48.4%; 95%CI: 30.2%, 66.9%; p = 0.25) in the ECMO control group. Isolated plasma exosomes containing the SARS-COV-2 Spike protein decreased after MSC infusions between day 14 or 21 after administration (p=0.003 and p=0.005, respectively) and was associated with a decrease in COVID-19 IgG Spike protein titer at same time points (p = 0.006 and p=0.007, respectively). Control ECMO patients receiving convalescent plasma did not clear COVID-19 IgG over the same time frame. InterpretationTogether these findings suggest that MSC IV infusion is well tolerated in patients with a broad range of severity including the most severe COVID-19 ARDS requiring ECMO. These data also raise the possibility that MSCs, in addition to exerting an immunomodulatory effect, contribute to viral clearance and strongly support the conduct of randomized placebo-controlled trial.
