Science 14Feb2020

SCIENCE sciencemag.org 14 FEBRUARY 2020 • VOL 367 ISSUE 6479 727

PHOTO: STR/AFP/GETTY IMAGES

T

he seeming precision of the global tal-

lies of cases and deaths caused by the

novel coronavirus now spreading from

Wuhan, China, belies an alarming fact.

The world is in the dark about the epi-

demic’s real scale and speed, because

existing tests have limited powers—and test-

ing is far too spotty. “We are underestimat-

ing how common this infection is,” cautions

Jeremy Farrar, head of the Wellcome Trust.

Within days of Chinese researchers re-

leasing the sequence of the virus on 11 Jan-

uary, scientists developed tests capable of

detecting genetic sequences that distinguish

the new agent from other coronaviruses cir-

culating in humans. By 28 January, China’s

National Medical Products Administration

had approved diagnostic test kits from

five companies. It was an astonishing pace

for the response to a pathogen never seen

before—and yet it was only a beginning.

Today, there aren’t nearly enough test kits

available to keep up with the skyrocketing

case numbers, and some parts of the world

may lack enough trained laboratory staff to

apply them. And because the genetic tests

look for snippets of viral genetic material

in nose and throat swabs or fluid collected

from the lung, they only work when some-

body has an active infection. Scientists are

still scrambling to detect antibodies against

the virus in the blood, which could help find

people who had an infection and recovered.

Hubei province, which includes Wuhan,

accounts for 75% of the more than 43,

confirmed cases of COVID-19, as the World

Health Organization (WHO) named the

new disease on 11 February. (A study group

of the International Committee on Taxon-

omy of Viruses christened the novel virus

severe acute respiratory syndrome corona-

virus 2, or SARS-CoV-2, the same day.)

But many news stories have reported

shortages of diagnostics in Hubei. “They’re

overwhelmed,” says epidemiologist Ian

Lipkin of Columbia University, who recently

returned from China and is in self-imposed

quarantine at home. Testing in Hubei has

focused on people sick enough to seek

medical care, so tens of thousands of milder

cases may not have been picked up. Outside

Hubei, testing is even patchier. “What’s the

full picture in the other parts of China?”

asks Keiji Fukuda, an epidemiologist at the

University of Hong Kong who previously led

outbreak responses at WHO.

Similar questions loom elsewhere. No

cases have been confirmed in Africa, but

there has been little testing. Initially, only

two African labs were capable of detecting

the virus, says John Nkengasong, who heads

the African Centres for Disease Control and

Prevention: “If this virus had shown up

in Africa in December, or early January, it

would have been devastating.” The conti-

nent is better prepared since a workshop in

Dakar, Senegal, last week where lab work-

ers from 15 African countries were taught

how to use one of the new viral tests, which

are based on the polymerase chain reaction

assay, Nkengasong says. (Another workshop

will follow next week.) Given that the virus

has spread so widely, however, Farrar says

he would be “very surprised” if it isn’t al-

ready in Africa.

Even in the United States, test kits are in

short supply. Regulations require that the

U.S. Centers for Disease Control and Preven-

tion (CDC) supply all tests, but that agency

only began to do so on 5 February and has

shipped a mere 200 kits so far, each able to

do at most 800 tests. U.S. officials still don’t

test most people flying in from China but

focus on those who have symptoms of the

disease. “We’re not able to do the surveil-

lance that we would want to do,” says Wendi

Kuhnert-Tallman, who heads CDC’s labora-

tory task force for the virus.

Many labs, including Lipkin’s, are rac-

ing to develop antibody tests, which will do

little to diagnose acute cases—it can take

weeks for that immune response to kick

in—but could help clarify mystifying ques-

tions about SARS-CoV-2’s spread.

Such tests use a surface protein of the

virus—or, in Lipkin’s case, an array of

peptides—to capture antibodies specific to

the virus in the blood. But a new test has to be

validated using blood from infected people.

CDC prefers to wait for 3 weeks after a per-

son becomes ill to let antibody levels build,

Kuhnert-Tallman says. So far, “We have one

single case in the U.S. that has reached the 21-

day mark.” A team led by Marion Koopmans

of Erasmus Medical Center in Rotterdam, the

Netherlands, expects to launch studies of its

first version of an antibody test next week. It

could be several more weeks before a com-

pany develops antibody kits and can churn

them out by the thousands.

Antibody tests might help pinpoint where

and when this outbreak began, and which

animal was the original source of the virus:

Researchers could search for evidence of in-

fection in stored samples of human blood

or in animals that might be a natural res-

ervoir of the virus. But the “most useful ap-

plication is to screen different age groups

of humans,” Koopmans says, to determine

how many people become infected with few

or no symptoms. If indeed scientists dis-

cover many mild cases, the rates of severe

disease (estimated at about 20%) and death

(2%) among infected people will plummet—

which would finally be a bit of good news. j

Lack of antibody tests obscures impact of the novel virus

A staffer at a Wuhan, China, hospital holds up a sample

from a suspected COVID-19 patient.

INFECTIOUS DISEASES

By Jon Cohen and Kai Kupferschmidt

Labs scramble to produce new

coronavirus diagnostics

Published by AAAS