New analysis from Scripps Research has found that anywhere from 30 to 40% of people with coronavirus are asymptomatic, but that doesn't mean they aren’t impacted by the disease.
Scripps Research cardiologist Eric Topol and his colleagues looked at research on over a dozen cohorts of coronavirus patients around the world. He found many of the patients that were asymptomatic still incurred lung abnormalities.
"People can go through a whole infection and not know it at all," he said.
"But the other thing that we uncovered that was a surprise to us, and I don't think most people know this, is that even though you don't have symptoms, which is silent enough as it is, there's another level of silence, which is you can have internal organ damage and not know it."
One study looked at CT scans conducted on individuals aboard the Diamond Princess cruise ship. In that case, 54% of 76 asymptomatic individuals showed significant subclinical lung abnormalities
Topol says the study also shows that many more people are spreading coronavirus without even knowing.
For example, in a study of more than 3,000 prison inmates who tested positive for coronavirus, around 96% of those cases were asymptomatic.
"In the United States, we were very slow to get testing ramped up. Even now, it's not ideal. So some people were under the radar because they didn't get a test," he said.
Topol says a lot of cities are opening up quickly. But the research shows the need for a cautious approach and more studies on how coronavirus affects internal organs.
KPBS reached out to the California Department of Public Health (CDPH) about the safety of reopening society, given emerging research on asymptomatic patients.
The Department wrote in an email, "studies continue to suggest that a proportion of people infected with novel coronavirus show no to minimal symptoms. How much these asymptomatic individuals contribute to transmission within the community is not clear. CDPH continues to monitor the scientific literature to better understand the role of asymptomatic individuals in transmission."
The Department emphasized the need for people to continue social distancing and wearing masks.
"When social distancing is not followed, the risk of transmission can increase. Wearing a cloth face covering or mask can also reduce your risk of getting and spreading the disease," the Department wrote.
"Given the incubation period of COVID-19 can be up to 14 days, effects of transmission of COVID-19 during mass gatherings may not be seen for several weeks. In addition to the incubation period following exposure, it takes additional time for a test to be done and reported before data are available to public health agencies. CDPH continues to closely monitor cases of COVID-19 in the community in close partnership with local health jurisdictions."
