The Centers for Disease Control and Prevention now estimate that about 35% of people with COVID-19 don’t exhibit symptoms, a significant jump compared to what health officials initially thought.
The CDC also estimated that 40% of transmission is believed to occur before the onset of any symptoms.
The disclosure raises serious concerns about how states and local officials can prevent outbreaks if about a third of Americans infected by the virus don’t know it.
Dr. Deborah Birx, coordinator of the White House coronavirus task force, said scientists had initially worked under the impression that around 11% to 15% of cases were asymptomatic.
She said the knowledge about potential transmission was a good reason to impose widespread testing in some communities, like nursing homes and meatpacking plants, where social distancing is difficult.
“Now we know it’s at least 35 [percent]. It may be greater than that because it may be so age dependent – that there may be a lot of people under 30 that have the virus and are shedding the virus and aren’t aware that they have the virus,” she said.
The CDC said the estimate will likely change as the agency learns more about the virus.