More than 3 million people in U.S. estimated to be contagious with the coronavirus

More than 3 million people in U.S. estimated to be contagious with the coronavirus

More than 3 million people in the United States have active coronavirus infections and are potentially contagious, according to a new estimate from infectious-disease experts tracking the pandemic. That number is significantly larger than the official case count, which is based solely on those who have tested positive for the virus.

The vast — and rapidly growing — pool of coronavirus-infected people poses a daunting challenge to governors and mayors in hard-hit communities who are trying to arrest the surge in cases. Traditional efforts such as testing, isolation of the sick and contact tracing can be overwhelmed when a virus spreads at an exponential rate, especially when large numbers of asymptomatic people may be walking around without even knowing they are infectious.

To put the 3 millionplusfigure in perspective: It is close to 1 percent of the population. It is about equal to the number of public school teachers in the entire country, or the number of truck drivers. If the University of Michigan’s football stadium were packed with a random selection of Americans, about a thousand of them would be contagious right now.

Columbia University epidemiologist Jeffrey Shaman said his team’s model estimated that 3.6 million people are infected and shedding enough virus to infect others. That’s a 34 percent week-to-week increase that followed a 36 percent increase in the previous seven-day average, he said.