About 72% of US counties — accounting for 94% of the population — likely already have coronavirus epidemics, according to a report from researchers at the University of Texas at Austin, first reported by The New York Times.

Even in counties with only one reported case, there's a 51% chance that an epidemic is already underway, the report said. That's because of the high percentage of asymptomatic and mild cases and limited testing.

"I worry that many local officials are waiting until there is clear evidence of local transmission before taking action," one of the report's authors told the Times.

The report recommended instead that local officials in all regions implement "proactive social distancing, even before two cases are confirmed."

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The coronavirus has spread far more widely in the US than the number of confirmed cases indicates, according to a new report from a team of disease modelers at the University of Texas at Austin.

Their modeling, which was first reported on by The New York Times, suggested that 72% of the US's 3,142 counties likely already have coronavirus epidemics, even if they don't know it yet. That accounts for 94% of the country's population.

At least 360,000 Americans across all 50 states, Washington, DC, and four territories have tested positive for COVID-19. However, given that testing availability is still limited, and that experts think between 25% and 50% of infected people could spread the disease without showing symptoms, the official count probably significantly underestimates the scope of the outbreak.

To arrive at their estimates, the UT Austin researchers repurposed a tool they previously used to analyze the Zika virus, another "silent spreader." They applied the framework to calculate the risk of widespread, undetected community transmission of COVID-19 in each US county, based the number of confirmed cases in each county as of April 2.

"For counties that have not yet reported a confirmed case, the chance that there is an undetected outbreak underway is 9%," the report said, but "a single detected case of COVID-19 increases that risk to 51%."

'We should not wait'

No national lockdown has been implemented in the US, though the vast majority of states have implemented stay-at-home orders. Still, some local officials are still waiting for a spike in confirmed cases before requiring residents to limit movement. Wyoming Senator John Barrasso told Fox News on Monday that his state didn't need a statewide lockdown because "people are spread out here. We only have about five people per square mile."

The report suggests waiting too long could cost lives.

"While low population density may help to delay the emergence and subsequent spread of the disease, COVID-19 has successfully spread in other rural regions of the US," Emily Javan, one of the report's authors, told Business Insider in a statement. "Our estimates suggest that all regions should take immediate preventative measures to mitigate community spread."

Florida Governor Ron DeSantis, who was criticized for leaving the state's beaches open to spring breakers, waited until last week to enact a statewide stay-at-home order. Restrictions were initially limited to counties in southwest Florida where confirmed cases were more highly concentrated.

"I worry that many local officials are waiting until there is clear evidence of local transmission before taking action ... The message is, we should not wait," Lauren Ancel Meyers, a professor of biology and statistics at UT Austin and an author of the report, told The New York Times.

Meyers and the other authors recommended in the report that officials implement "proactive social distancing, even before two cases are confirmed."

"Early and extensive social distancing can block community transmission, avert rises in hospitalizations that overwhelm local capacity, and save lives," they wrote.