A majority of Americans who are diagnosed with COVID-19 don't know who passed the virus to them, two new government reports show.
In the first study, researchers found that only 27 percent of more than 360 Colorado residents diagnosed with COVID-19 knew of any contact with someone who had coronavirus in the two weeks before they were tested.
That percentage was higher in a second study, with 46 percent of 350 people diagnosed certain about who might have infected them. But both studies suggest that most people infected with coronavirus don't actually know who exposed them.
"This just emphasizes the fact that while we know how COVID-19 is transmitted we do not have a good idea of how to assess our risk when interacting with other people," said Dr. Eric Cioe Pena, Director of Global Health at Northwell Health, New Hyde Park, NY.
He wasn't involved in the new study, but said it shows how, "important it is that we maintain distance from people that are not in our household, wear a mask, and keep up our vigilance so that we can protect our communities from this virus."
Among those in the study who knew they had come into contact with an infected person, the most commonly reported relationship was a family member (27 percent) or a coworker (25 percent) in the Colorado study. In the second study, it was most often a family member (45 percent) or a work colleague (34 percent).
Both reports were published June 30 by researchers from the U.S. Centers for Disease Control and Prevention in the agency's publication Morbidity and Mortality Weekly Report.
"Fewer than one-half of patients were aware of recent close contact with someone with COVID-19, highlighting a need for increased screening, case investigation, contact tracing and isolation of infected persons during periods of community transmission," the researchers of the second study wrote. "A majority of COVID-19 patients reported working during the two weeks preceding illness, and few had the ability to telework, underscoring the need for enhanced measures to ensure workplace safety."
Those measures should include social distancing and more widespread use of face masks, they added.
In the Colorado study, the most commonly reported activities in the two weeks before becoming ill included attending gatherings of more than 10 persons (44 percent), traveling domestically (29 percent), working in a health care setting (28 percent), visiting a health care setting not as a health care worker (23 percent), and using public transportation (22 percent).
"These findings highlight the need for anyone with COVID-19 compatible symptoms to avoid public settings and isolate from other persons, even within their own household, when possible," the Colorado researchers wrote. "Because workplaces are common locations of potential exposure to persons with COVID-19, it is important that company officials and managers refer to CDC's guidance for workplaces during the COVID-19 pandemic to minimize risk for exposure for their employees and customers."
The CDC reports come as many states across the country are battling surges in coronavirus infections and hospitalizations as they try to reopen for business.
At least a dozen states and cities have slowed reopening plans, the Washington Post reported Tuesday.
Not only case counts are climbing: COVID-19 hospitalizations are spiking in seven states, the Post reported. In Texas, Arizona, Nevada, South Carolina, Montana, Georgia and California, seven-day averages are up at least 25 percent from last week.
"Because ongoing data indicates that asymptomatic and pre-symptomatic transmission makes up the majority of spread of COVID-19, it's vital that everyone wear a mask in public settings and when around people outside of their household, specifically when they are unable to adhere to social distancing," said Dr. Robert Glatter, an emergency room doctor at Lenox Hill Hospital in New York City.
"As the pandemic worsens, we need a stronger federal response," Glatter added. "This means, first and foremost, a federal law mandating wearing of masks in public settings when social distancing is not possible."
Visit the U.S. Centers for Disease Control and Prevention for more on COVID-19.
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