Objectives
This report investigated the simulated effect of several vaccination scenarios on COVID hospitalizations and deaths in Jefferson County, Kentucky. Study Design: Eight scenarios were considered. First, it was assumed that the status quo scenario (∼30,000 doses of Pfizer and Moderna vaccines distributed and administered every week) would continue without Johnson & Johnson’s vaccine. Then, three scenarios of the addition of Johnson & Johnson’s vaccine (10,000, 15,000, and 20,000 weakly) were considered. Next, an expansion over the status quo scenario (∼40,000 doses of Pfizer per week) was considered with and without Johnson & Johnson’s vaccine scenarios.
Methods
An epidemic dynamics model (namely, a Susceptible-Exposed-Infectious Recovered (SEIR) model) is adopted and estimated in this study. In the model, transmission through different phases of the COVID-19 epidemic (susceptible, exposed, infectious, hospitalized, vaccinated, recovered, and dead) is regulated with transmission and clinical dynamics parameters. Key transmission parameters are the population, basic and effective reproduction factors, lengths of incubation periods, pre-infectiousness, infectiousness with and without symptoms, and vaccines’ efficacy rates and coverage. Key clinical dynamics parameters are hospitalization rate among the symptomatic, time from onset of severe symptoms to hospitalization, length of hospital stay, fatality rate among the hospitalized, recovery time among the hospitalized, the time from hospitalization to death.
Results
More intense vaccination than the status quo is expected to decrease hospitalizations and deaths in the next three months. However, the magnitude of the decrease in deaths is small, < 3 dozen. Importantly, it is expected that the COVID-19 infection continues to spread. Therefore, social distancing and other COVID-19 protection measures (for example, mask-wearing) must continue – should they be relaxed, a “during vaccination surge” will occur and should be expected in the late April-early May period.
Conclusions
Implications for Policy or Practice are Social distancing and other COVID-19 protection measures (for example, mask-wearing) must continue.
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