FRIDAY, Feb. 21, 2020 — A report from doctors battling China’s coronavirus outbreak raises concern that people who have no symptoms and initially test negative on medical tests might still harbor and spread the COVID-19 virus.
The case involves an asymptomatic 20-year-old woman who appears to have spread the illness to five relatives who later became ill.
If similar reports are found elsewhere, “the prevention of COVID-19 infection would prove challenging,” warned researchers led by Dr. Meiyun Wang of Henan Provincial People’s Hospital in Zhengzhou, China.
While the rate of new cases in China appear to be slowing, outbreaks in countries such as South Korea and Iran have experts worried that COVID-19 could go global.
As of Friday, a total of more than 75,000 cases and 2,236 deaths were reported in mainland China.
For many infectious respiratory illnesses, people have to be symptomatic to transmit the infection to others. But the new report suggests that might not always be the case for COVID-19.
As Wang’s team explained, five members of a family in the Chinese city of Anyang came down with coronavirus about 10 days after meeting up with a 20-year-old female relative. The young woman had traveled to Anyang from her home in Wuhan, thought to be the origin of the coronavirus outbreak.
The woman arrived in Anyang on Jan. 10, and met with the five family members over the next three days. All of the five became symptomatic for COVID-19 between Jan. 17 and Jan. 26.
Importantly, “none of the patients had visited Wuhan or been in contact with any other people who had traveled to Wuhan” — except their 20-year-old relative.
What’s troubling about this case is that the young woman never developed symptoms of coronavirus infection, nor did any signs of infection show up on multiple tests, Wang’s group reported Feb. 21 in the Journal of the American Medical Association.
“As of Feb. 11, she had no elevated temperature measured or self-reported fever and no gastrointestinal or respiratory symptoms, including cough or sore throat, reported or observed by physicians,” Wang and colleagues noted.
Furthermore, highly sensitive throat-swab tests gave inconsistent results: One came back negative on Jan. 26, another was positive two days later, but two more (Feb. 5 and Feb. 8) came back negative.
As well, “chest CT images on Jan. 27 and 31 showed no significant abnormalities,” the Chinese researchers reported.
In contrast, all of the five symptomatic patients developed pneumonias, although none have died.
Wang’s team pointed out that a prior case of an infected but symptom-free person transmitting COVID-19 has been reported. That case involved a 10-year-old boy, but he at least gave hints of infection due to “abnormalities on chest CT,” the researchers said.
And if the young woman implicated in the new cluster of cases had no symptoms, it also begs the question of how she might have spread COVID-19 to others.
Right now, “the mechanism by which asymptomatic carriers could acquire and transmit the coronavirus that causes COVID-19 requires further study,” Wang and colleagues noted.
One expert in the United States believes more study is warranted, and he stressed it’s too early to press the panic button based on this case alone.
For example, “it’s unclear if the first [throat swab] test was falsely negative from improper sampling, a defective test kit, or an inadequate sampling of the nose and throat secretions,” noted Dr. Robert Glatter. He is an emergency physician at Lenox Hill Hospital in New York City.
“We will have to see if additional cases of asymptomatic transmission are reported, along with virologic data and contact tracing, before making any conclusions regarding the case presented in this report,” Glatter said.
The U.S. Centers for Disease Control and Prevention has more on the new coronavirus.
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