麻豆传媒

Human-to-human transmission of novel coronavirus was reported within a family in Vietnam, as evidence of transmission of the virus outside of China continued to mount.

A family cluster of novel coronavirus infection included a Chinese man who traveled from Wuhan to Vietnam, and the man's adult son who stayed with his parents for three days after the father's return from China, reported Thuong V. Nguyen, MD, PhD, of Pasteur Institute in Ho Chi Minh City, Vietnam, and colleagues in the

This is the most detailed of at least four reports of transmission outside of China. Also on Tuesday, news reports from Germany indicated that four people who had come for a business meeting; the colleague tested positive for the coronavirus on his return to China, according to Reuters, and now so have the four co-workers.

Japan also documented a case of person-to-person transmission on Tuesday, which was not linked to recent travel in China. According to The Japan Times, from Nara prefecture, southeast of Osaka, who "drove buses with tour groups from [Wuhan] twice this month."

On Monday, Canadian authorities said a , who had returned from Wuhan and tested positive for the virus.

But not all domestic transmission is the same. Prior to the NEJM publication, Amesh Adalja, MD, spokesperson for the Infectious Diseases Society of America, cited cases of "family clusters" of novel coronavirus in both China and Vietnam.

"When we talk about human-to-human transmission, family members often have intimately close contacts," he told 麻豆传媒 on Monday. "It's not taken to be representative of the general public."

Coronavirus is transmitted through respiratory droplets, meaning exposure is within six feet of the patient, Adalja said, but that is not the same thing as a virus with sustained human-to-human transmission, such as influenza.

"We're still learning a lot about the transmission of [novel coronavirus]," he noted.

Nguyen and colleagues detailed the case of a Chinese man, age 65, with a history of hypertension, type 2 diabetes, a stent for coronary heart disease, and lung cancer. He was admitted to a hospital in Vietnam on Jan. 22 with low-grade fever and fatigue after feeling ill four days after he flew to Hanoi from Wuhan with his wife.

In addition, the man's adult son, age 27, accompanied his father to the hospital on Jan. 22 with symptoms of his own -- fever, vomiting, and loose stools -- after sharing a hotel room with his parents several days earlier in central Vietnam. The son had not traveled anywhere the coronavirus was known to be circulating.

However, the man's wife was healthy as of January 28, Nguyen's group said.

Noting that the son's symptoms developed on Jan. 20 after meeting his parents on Jan. 17, the authors said, "this suggests the incubation period for 2019-n-CoV may have been three days or less in this case."

The man was isolated, treated with broad-spectrum antibiotics, antiviral agents, and supportive therapies, the authors said. A chest radiograph revealed an "infiltrate" in the man's lung and he was given supplemental oxygen. His fever disappeared as of Jan. 25, with his clinical condition improving the next day.

His son, meanwhile, showed no laboratory abnormalities except for an elevated C-reactive protein level, and no abnormalities on a chest radiograph and was in stable condition after Jan. 23. Both father and son tested negative for influenza and dengue, and tested positive for novel coronavirus.

But researchers noted that while the father is presumed to be the source of the son's infection, "sequencing of strains from the two patients to ascertain transmission of 2019-nCoV from the father to the son has not been performed."

They added that they are currently following 28 close contacts of the family, but none have developed infection.

"This family cluster of 2019-nCoV infection that occurred outside China arouses concern regarding human-to-human transmission," Nguyen and colleages concluded.

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