In July, the highly contagious Delta variant of SARS-CoV-2 kindled another wave of hospitalizations and deaths in several U.S. states. Most of these tragically preventable events occurred among unvaccinated adults, but the toll also includes an increasing number of children. Unvaccinated individuals face a fivefold higher rate of infection and a 29 times higher hospitalization risk than their vaccinated counterparts.
Nationally, new COVID-19 cases surged near the end of August to a seven-day average of 160,000 per day. But during September, several southern states that were hit hard during July and August started to see infections and hospitalizations ebb while other states with lower rates during the summer began to see rates pick up. The percentage of population vaccinated varies substantially among states. In some, nearly 70 percent of the population have been fully vaccinated while others have only recently achieved 40 percent. Despite the ongoing Delta wave and the imminent threat of new regional outbreaks, the pace of vaccination slowed recently to fewer than 700,000 doses per day; this could leave millions vulnerable for many months and add to the occurrence of preventable hospitalizations and deaths.
What would happen if we significantly accelerated the pace of vaccination? To forecast the impact during the next six months, we used a previously developed simulation model of COVID-19 transmission dynamics. We considered five southern states that are currently in a declining trend, past their peak number of infections in early September (Alabama, Florida, Georgia, Louisiana, and Texas) and five northern states with an upward trend in infections at the end of September (Michigan, New Hampshire, New York, Pennsylvania, and Wisconsin). We simulated a scenario in which each state would increase the daily number of vaccine doses delivered by 50 percent above their pace during the last week of August 2021. We compared that to a status quo scenario under which vaccinations continued at the August pace.