© 2024 Milwaukee Public Media is a service of UW-Milwaukee's College of Letters & Science
Play Live Radio
Next Up:
0:00 0:00
Available On Air Stations

Studies Show Coronavirus Spread Earlier Than We Knew


One million - that's almost how many people have tested positive for the coronavirus here in the United States so far. But even that staggering number is almost certainly an underestimation because last week, we learned that the virus was present and spreading in the U.S. weeks earlier than we were told. NPR's Nathan Rott has this report.

NATHAN ROTT, BYLINE: The established timeline of when the coronavirus outbreak took off in this country got a few shocks last week. Two came in the form of serology tests. That is tests that look to see if people have antibodies to an infection. Preliminary results from one study found that 1 in 5 residents who were tested in New York City already had antibodies, meaning they may have had the coronavirus. Statewide, the results indicate that more than 2 million people could've had it. Here's New York Governor Andrew Cuomo.


ANDREW CUOMO: This basically quantifies what we've been seeing anecdotally and what we have known, but it puts numbers to it.

ROTT: A similar survey in Miami-Dade County in Florida found that 6% of those tested also had antibodies. Now, health officials stress these results are preliminary, and way more antibody testing needs to be done. But they weren't the only new signs last week that the pandemic may have taken off here in the U.S. earlier than believed.


SARA CODY: Good morning. I'm Dr. Sara Cody. I'm the health officer for the county of Santa Clara. Thank you all...

ROTT: In California, health officials made a stunning announcement last week. Autopsies of two people who died in early and mid-February, weeks before the first believed coronavirus death in the U.S., had tested positive for COVID-19. The first death, a 57-year-old woman, happened on February 6, when the CDC said there were only 11 known cases in the entire country.


CODY: What these deaths tell us is that we had community transmission, probably to a significant degree, far earlier than we had known.

ROTT: Community transmission meaning the virus was being spread silently through the Bay Area before anyone knew it.

ALESSANDRO VESPIGNANI: What we call the invisible stage of the disease.

ROTT: Dr. Alessandro Vespignani is the director of the Network Science Institute at Northeastern University in Boston. He and a team of other researchers have created a model that simulates and forecasts the virus spread. He compares it to tracking an invisible hurricane. And looking back at that hurricane's path, their model shows...

VESPIGNANI: While we had a few case detected in the United States, actually, we already had hundreds and then thousands of transmission events across the country.

ROTT: A lot of the discussion about when the virus spread and to what degree has been centered on the politics of the situation. Did stay-at-home orders come soon enough? Did the Trump administration take the threat as seriously as they should have? But Vespignani and other health officials say the real value in knowing when things happened is so they can better forecast what might happen as different parts of the country start opening back up.

VESPIGNANI: The first question is, yes, I want to reopen. It's crucial. I can't wait to go out and finally resume my social life. But what are we doing so that we are not falling in the trap of February?

ROTT: A trap where the virus spreads through the population, invisible and undetected, another time.

Nathan Rott, NPR News, Los Angeles. Transcript provided by NPR, Copyright NPR.