Models show omicron may have peaked in US
Crest of infections has passed, but hospitalizations, deaths lag
Omicron hit the USA hard and fast in the past month, but modeling by several universities shows the wave of infections may have crested – and hospitalizations and deaths should follow.
COVID-19 infections peaked Jan. 6, according to researchers at the Institute for Health Metrics and Evaluation at the University of Washington's School of Medicine.
“We peaked at 6.2 million infections,” said professor of epidemiology and health metrics Ali Mokdad.
That's close to estimates by the University of Texas, Austin COVID-19 Modeling Consortium, which puts the peak somewhere between Jan. 9 and 13.
“That's a range between the most pessimistic and optimistic scenarios,” said Lauren Ancel Meyers, director of the consortium.
The crest came more quickly than the University of Washington group estimated last month, when they anticipated it would hit Jan. 27.
“Omicron came in and spread so fast it infected everybody who could be infected. Also, it was the holidays, so people were traveling, which increased the spread,” Mokdad said.
Mokdad's group estimated that by Jan. 3, at least 57% of Americans had COVID-19 at least once. The model presumes for every one reported case of COVID-19, there are five actual cases.
Because hospitalizations lag infections by about two weeks, the University of Washington team estimated the daily U.S. hospital census, including incidental admissions with COVID-19, will peak by Jan. 25 at 273,000.
Omicron has proved to be milder: 7 in 1,000 infections, or 0.7%, result in hospitalization, according to Mokdad's group. The rate on Nov. 4, while delta was the dominant strain, was 33 of every 1,000, or 3.3%.
Though less severe than delta, omicron is much more contagious, so the numbers will still be high, said Jeffrey Shaman, an infectious disease modeler and epidemiologist in the department of environmental health sciences at the Mailman School of Public Health at Columbia. His team built one of the first COVID-19 models.
“A lower percentage of people become severely ill, but so many more people are being infected that it comes out to large numbers nonetheless,” Shaman said.
Because of that, U.S. hospitals are in for a rough January.
“What we've found in prior waves of COVID, during these periods when hospitals are at or above capacity, patients don't fare as well, they're more likely to die,” Meyers said. “There isn't the level of equipment, there just aren't enough health care workers to provide the level of care we want to provide.”
Reported deaths will rise to 1,930 per day by Jan. 24, the Washington team's model predicts.
That's much lower than last winter's 3,400 daily peak death rate, when vaccinations had just begun and treatments were being figured out, Mokdad said. The model predicts total U.S. COVID-19 deaths at 905,000 by April 1. As of Tuesday, more than 840,000 Americans had died from the virus, according to Johns Hopkins University.