It’s likely the United States will see another surge of COVID-19 this winter, warned Christopher Murray, MD, director of the Institute for Health Metrics and Evaluation (IHME) at the University of Washington in Seattle.
Speaking at the national conference of State of Reform on April 8, Dr. Murray cited the seasonality of the SARS-CoV-2 virus, which wanes in the summer and waxes in the winter. The “optimistic forecast” of IHME, which has modeled the course of the pandemic for the past 13 months, is that daily deaths will rise a bit in the next month, then decline from May through August, he said.
“Summer should be fairly quiet in terms of COVID, if vaccinations rise and people don’t stop wearing masks,” Dr. Murray said.
But he added that “a considerable surge will occur over next winter,” because the new variants are more transmissible, and people will likely relax social distancing and mask wearing. The IHME predicts that the percentage of Americans who usually don masks will decline from 73% today to 21% by Aug. 1.
With a rapid decline in mask use and a rise in mobility, there will still be more than 1,000 deaths each day by July 1, Dr. Murray said. In a forecast released the day after Dr. Murray spoke, the IHME predicted that by Aug. 1, there will be a total of 618,523 U.S. deaths from COVID-19. Deaths could be as high as 696,651 if mobility among the vaccinated returns to prepandemic levels, the institute forecasts.
Based on cell phone data, Dr. Murray said, the amount of mobility in the United States has already risen to the level of March 2020, when the pandemic was just getting underway.
If there’s one piece of good news in the latest IHME report, it’s that the estimated number of people infected (including those not tested) will drop from 111,581 today to a projected 17,502 on Aug. 1. But in a worst-case scenario, with sharply higher mobility among vaccinated people, the case count on that date would only fall to 73,842.
The SARS-CoV-2 variants are another factor of concern. Dr. Murray distinguished between variants like the one first identified in the U.K. (B.1.1.7) and other “escape variants.”
B.1.1.7, which is now the dominant strain in the United States, increases transmission but doesn’t necessarily escape the immune system or vaccines, he explained.
In contrast, if someone is infected with a variant such as the South African or the Brazilian mutations, he said, a previous COVID-19 infection might not protect the person, and vaccines are less effective against those variants.
Cross-variant immunity may range from 0% to 60% for escape variants, based on the slim amount of data now available, Dr. Murray said. In his view, these variants will be the long-term driver of the pandemic in the United States, while the United Kingdom variant is the short-term driver.
The latest data, he said, show that the Pfizer/BioNTech and Moderna vaccines are 75% effective against the escape variants, with lower efficacy for other vaccines. But booster shots may still be required to protect people against some variants.