Over 3 million people in the U.S. are estimated to be contagious with COVID-19, according to a study from Columbia University.
University epidemiologist Jeffrey Shaman told The Washington Post his team’s model estimated 3.6 million people are infected in the U.S. and shedding the virus onto others.
Separate modelers from the University of Washington’s Institute for Health Metrics and Evaluation (IHME) estimated a similar number Tuesday, showing approximately 3.2 million people are infected.
Notably, the estimate also does not include an approximately equal number of dormant infections among people who caught the virus in recent days but cannot yet pass it on because it is still incubating.
The estimated figures contradict tallies from sources such as the Post, which have reported roughly 1.95 million new cases within the same period this month tracked by local health officials.
Researchers say the numbers differ because COVID-19 outbreaks have become more widespread, and some might be infected with the virus but remain asymptomatic, unknowing they even contradicted the illness.
Still, according to The Atlantic’s COVID-19 Tracking Project, the U.S. is now conducting the most extensive sum of tests daily, roughly 1.5 million new ones each day. The U.S. has performed over 170 million tests in total.
To put that in perspective, Statista reported the U.S. conducted less than half of that number of tests, 53.8 million, from March 1 to July 30.
The only period since the virus’s outset comparable to November’s reports from IHME and Columbia happened earlier this year in late March and early April, when Centers for Disease Control and Prevention (CDC) Director Robert Redfield estimated the number of infected people could be 10 times the tallies from health departments.
IHME researchers found their estimate by working backward from the known number of deaths related to COVID-19.
Ali Mokdad, an epidemiologist at IHME, said his data relies on an estimated infection fatality rate of 0.6 percent across all populations.
While mortality rates remain lower than their peak earlier in the pandemic, the rise of infections in September has seen a delayed echo in the increase of the death toll as the U.S. nears 250,000 total fatalities related to COVID-19.