University of South Florida



USF epidemiologist: Vaccination rate must double to slow transmission of COVID-19

The slackening of vaccinations is leading to a large resurgence of COVID-19 infections in Florida. New data provided by University of South Florida College of Public Health epidemiologist Edwin Michael and colleague Ken Newcomb shows that there’s been a 70 percent drop in the rate of people getting vaccinated in Hillsborough County since April. There are currently 2,000 people receiving the vaccine each day. Unless that figure doubles, Michael says control of the resurgence of the pandemic during the fall will not be achieved.

Edwin Michael

Edwin Michael, professor of epidemiology

“The upsurge in cases and hospitalizations is due to fewer vaccinations, relaxation of social distancing measures, greater population mobility, plus the spread of more contagious variants, which are also slightly better in evading immunity and likely cause more symptomatic disease compared to the original variant,” Michael said. “These predictions warn that until vaccination rates are ramped up to achieve herd immunity over this fall, people will still need to follow social distancing measures, such as wearing face coverings at the very least, to protect themselves and to reduce infection spread.”

Michael’s SEIRcast COVID-19 Forecast and Planning Portal shows that the slowing of vaccination since April combined with a steady reduction in the practice of social mitigation measures and the spread of the highly contagious alpha and delta variants will lead to a new spike in cases by mid-September, with 2,800 cases reported in Hillsborough County each day. The size of this spike will be three times greater than the second wave that occurred last winter.

He expects this to be the final wave of the pandemic and will primarily occur within the unvaccinated population. However, this will prompt a new surge in hospitalizations, potentially exceeding hospital bed capacity.

While there have been some infections reported by vaccinated individuals, their cases have been relatively mild, with very few requiring hospitalization. Nearly 48 percent of the population in Florida has been fully vaccinated. Michael says we will not reach herd immunity until that figure increases to 85 percent. This is higher than previous projections due to the prevalence of dominant variants. He says the next two months are crucial in trying to put an end to the pandemic.

There are many opportunities to receive the COVID-19 vaccine, including on USF’s campuses. For more information, please visit the USF Returning to Campus website.

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