A man in Seattle has been
confirmed as the first U.S. case of a novel coronavirus that emerged in central China, where it has killed
six people and sickened hundreds more in recent weeks, according to the U.S.
Centers for Disease Control and Prevention.
Officials are also ramping
up health screenings at U.S. airports, after Chinese public health officials said January 20
that the virus can spread from person to person — a factor that raises concerns
of an international epidemic emerging.
It’s still unclear how easily the
virus spreads between humans. The World Health Organization said it would
convene an emergency committee on January 22 in Geneva to decide whether to
declare a global health emergency.
“The confirmation that
human-to-human spread with this virus is occurring in Asia certainly raises our
level of concern,” said Nancy Messonnier,
director of the CDC’s National Center for Immunization and Respiratory
Diseases, during a telephone news conference on January 21. However, the agency
believes the risk “to the American public at large remains low at this time.”
The Seattle patient in his 30s was
diagnosed after seeing a doctor for respiratory symptoms, Messonnier said. The man had returned last week
from Wuhan, and is no longer “clinically ill,” she said.
The first people reported to have
the pneumonia-like illness became sick in December, after visiting a wild
animal market in the central Chinese city of Wuhan. Officials soon confirmed
that the outbreak was caused by a novel
coronavirus (SN: 1/10/20) — the same family of viruses that causes
severe acute respiratory syndrome, or SARS.
On January 20, China’s lead
scientist monitoring the outbreak, Dr. Zhong Nanshan, gave a statement on Chinese
state television confirming that at least two patients who had never been to
Wuhan had been infected by family members who recently had traveled to the
city. At least 15 health care workers are also among at least 278 cases
reported by China.
Scientists are still trying to understand how dangerous the virus is. Most of the six people who died had been suffering with a preexisting health condition, says Jennifer Nuzzo, an epidemiologist at the Johns Hopkins Center for Health Security in Baltimore. And it’s unclear if the recent jump in cases is due to the virus spreading further, or simply heightened surveillance, she says.
Also unclear, she says, is how
exactly the virus spreads. “Can a sick person easily transmit the disease when
they’re out in the community? Or can it only be transmitted in risky situations,
for example, when a health care worker is caring for a patient and their
personal protective equipment fails?”
Experts also need more information about
newer cases not directly tied to the Wuhan animal market, she says. Detailed
patient histories can help in tracing sources of infection, but that
information has yet to reach the international public health community, she
The severity of illness caused by the
virus also is unclear, with details about the condition of patients in China
yet to be shared widely, says infectious disease
physician Amesh Adalja, also at Johns Hopkins Center for Health Security. “Are
they requiring oxygen therapy? Intravenous fluids? Those types of questions are
really important in helping us know where to place this outbreak in terms of
risk,” Adalja says.
The CDC said
passengers arriving on direct or connecting flights from Wuhan would be
funneled through five international airports conducting health
screenings — in New York City, Atlanta, Chicago, Los
Angeles and San Francisco. Cases have also been reported in people who had
traveled from China to Thailand, Japan and South Korea. Russian and Canadian
airports are also screening some arriving passengers.
“We’re taking a
proactive approach,” the CDC’s Messonnier said. “So far CDC staff have screened
over 1,200 individuals” at airports, though none have tested positive for the
If the WHO decides
to declare the coronavirus a public health emergency, the global
health watchdog may suggest travel restrictions or other recommendations. Amid the 2014 outbreak of another coronavirus called Middle East
respiratory syndrome, or MERS, the WHO “declined to declare MERS an
international emergency,” Nuzzo says. But that was “largely because there
wasn’t evidence of sustained human transmission.”