With delta variant dominant, COVID-19 Simulator sees surge in deaths

As delta surges, what can we expect if vaccination and mask-wearing rates don’t change?

According to investigators who previously developed the COVID-19 Simulator — which models the trajectory of the illness in the U.S. at the state and national levels — the combination of variant’s high transmissibility, low vaccination coverage in several regions, and more relaxed attitudes toward social distancing will likely lead to a surge in COVID-19–related deaths in at least 40 states.

And if current social distancing behaviors and vaccination rates remain unchanged, the simulator predicts that in several states, daily COVID-19–related deaths could exceed the peak seen in early 2021.

The researchers applied the tool to potential scenarios in which the COVID-19 delta variant becomes dominant in every state. Its analysis, published on the preprint server medRxiv, showed an additional 157,000 COVID-19-related deaths could occur across the U.S. between August 1 and December 31. It projected approximately 20,700 delta-related deaths in Texas, 16,000 in California, 12,400 in Florida, 12,000 in North Carolina, and 9,300 in Georgia. In contrast, the projected number of COVID-19-related deaths would remain below 200 in New Jersey, Massachusetts, Connecticut, Vermont, and Rhode Island.

The team’s projections are updated weekly by incorporating vaccination rates and social-distancing measures in each state, and the latest results can be found at the simulator website.

“If we want to end this pandemic, then all Americans need to be vaccinated and at least right now, we should be masking when in public indoor spaces.”
— Benjamin P. Linas, professor of medicine at Boston University School of Medicine

“These projections should serve as a warning sign, especially in states that could have higher daily COVID-19 deaths than their previous peaks,” said lead author Jagpreet Chhatwal, associate director of Massachusetts General Hospital’s Institute for Technology Assessment and an assistant professor at Harvard Medical School. “We also hope that our projections can help policymakers bring back mask mandates and further advocate for COVID-19 vaccines.”

Senior author Benjamin P. Linas, a professor of medicine at Boston University School of Medicine, added that while there had been hopes that the pandemic was waning, additional action is needed.

“If you are not vaccinated, you are at high risk because of the delta variant. August 2021 is potentially more dangerous to you than August 2020,” he said. “If you are vaccinated, you are much safer, but you should still care about this ongoing transmission because it creates the circumstances that generate new variants. If we want to end this pandemic, then all Americans need to be vaccinated and at least right now, we should be masking when in public indoor spaces.”

Co-author Jade Yingying Xiao, a Ph.D. student at Georgia Tech, noted that if recent estimates of the delta variant’s reproduction number are correct, then the team’s model implies current levels of social distancing are reducing transmission by 30 percent to 40 percent “We can easily foresee this number dropping as we move ahead into the fall months with schools and colleges reopening,” she said.