ABSTRACT
OBJECTIVE: Emerging SARS-COV-2 variants are spurring the development of adapted vaccines as public health authorities plan for fall vaccinations. This study estimated the number of infections and hospitalizations prevented by three potential booster strategies for adults (≥18 years) in the United States: boosting with either Moderna's (1) licensed first generation monovalent vaccine mRNA-1273 (ancestral strain) or (2) candidate bivalent vaccine mRNA-1273.214 (ancestral + BA.1 variant of concern [VOC]) starting in September 2022, or (3) Moderna's updated candidate bivalent vaccine mRNA-1273.222 (ancestral + BA.4/5 VOC) starting November 2022 due to longer development time. METHODS: An age-stratified, transmission dynamic, Susceptible-Exposed-Infection-Recovered (SEIR) model, adapted from previous literature, was used to estimate infections over time; the model contains compartments defined by SEIR and vaccination status. A decision tree was used to estimate clinical consequences of infections. Calibration was performed so the model tracks the actual course of the pandemic to present time. RESULTS: Vaccinating with mRNA-1273(Sept), mRNA-1273.214(Sept), and mRNA-1273.222(Nov) is predicted to reduce infections by 34%, 40%, and 18%, respectively, and hospitalizations by 42%, 48%, and 25%, respectively, over 6 months compared to no booster. Sensitivity analyses around transmissibility, vaccine coverage, masking, and waning illustrate that boosting with mRNA-1273.214 in September prevented more cases of infection and hospitalization than the other vaccines. LIMITATIONS AND CONCLUSIONS: With the emergence of new variants, key characteristics of the virus that affect estimates of spread and clinical impact also evolve, making parameter estimation difficult. Our analysis demonstrated that boosting with mRNA-1273.214 was more effective over 6 months in preventing infections and hospitalizations with a BA.4/5 subvariant than the tailored vaccine, simply because it could be deployed 2 months earlier. We conclude that there is no advantage to delay boosting until a more effective BA.4/5 vaccine is available; earlier boosting with mRNA-1273.214 will prevent the most infections and hospitalizations.
Subject(s)
COVID-19 , SARS-CoV-2 , Adult , COVID-19/prevention & control , Humans , Public Health , SARS-CoV-2/genetics , United States , Vaccines, CombinedABSTRACT
How important is the relaxation of contact restrictions for the recovery of the German economy and what conclusions can be drawn for the appropriate level of contact restrictions in the coming months? In considering these issues, an attempt will be made to assess what significance the contact restriction measures introduced by the federal and state governments since mid-March 2020 will actually have for the current slump in economic activity in Germany. In addition, the various plausible scenarios for the spread and containment of infection are presented with different options for easing contact restrictions.