BBC Science Focus - 02.2020

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WHEN DID THE OUTBREAK START?

On 31 December 2019, China contacted the World Health

Organization (WHO) to inform them of an outbreak of

‘pneumonia of unknown cause’ in Wuhan, a city in the

country’s central Hubei province.

A week later, on 7 January 2020, the Chinese authorities

investigating the outbreak confirmed that a previously

unknown strain of coronavirus was to blame. It was

believed to have originated in one of Wuhan’s animal

markets, where it had jumped species from an as-yet-

unidentified animal into humans.

By 11 January the coronavirus, temporarily designated

2019-nCoV, had claimed its first life. Over the next 10

days, the news broke that human-to-human transmission

of 2019-nCoV was possible. The virus killed two more

people, and cases of it turned up in Thailand, Japan, South

Korea, Vietnam and the US. WHO met to determine

whether the situation constituted a global emergency.

As of Monday 27 January, less than a month after the

initial alert, 10 cities in Hubei are in a state of lockdown

and airports around the globe are screening passengers

arriving from Wuhan. The virus has reached Australia

and France, the number of confirmed cases is up to

almost 3,000 and rising.

BUT HOW SERIOUS IS IT?

The 2019-nCoV virus presents with flu-like symptoms but

is capable of causing respiratory distress, pneumonia and

potentially death. Furthermore, it’s contagious before the

symptoms show.

“It’s a serious situation. We’re approaching it with

caution but I don’t think alarm,” says Prof Mark Fielder, a

medical microbiologist at Kingston University. “What we

need to remember is that most of the cases – in fact, I’m

going to say all of the cases as things stand now – have

come from people with direct links to Wuhan or other

local cities where the virus is known to be present.”

According to Fielder, the virus hasn’t moved into people

without direct links to Wuhan – it will be more

concerning if that happens. Many people, once they are

given supportive care, seem to fight the virus off and get

better. “A number of the patients who unfortunately lost

“Most of the cases have come from people with

direct links to Wuhan or other local cities where

the virus is known to be present”

LEFT

Colourful

lanterns

decorate a

Beijing park,

but the Lunar

New Year

festivities

were

cancelled to

reduce risk of

infection

ABOVE In

Zhongnan

Hospital,

Wuhan, a

doctor and a

patient bid

each other

greetings

for the Lunar

New Year

their lives have also had other diseases, so they’ve perhaps

not been quite so fit in the first place,” says Fielder.

At the time of writing, the coronavirus is still spreading.

But despite the seemingly steep rise in the number of cases,

the outbreak remains within estimates of its expected

incidence. WHO has put the total number of expected cases at

4,000, with a margin for error from 1,000 to 9,700.

“[The reason] we’ve seen a rise in the number of cases is, I

think, a conglomeration of factors. If it did emerge from this

market, which does seem likely, then obviously quite a lot of

people attended that market, especially as people were

probably getting provisions for the New Year celebrations in

China,” explains Fielder. “But we can’t tell how many people

were in that market and where they went afterwards or where

they’d come from before. Also, it takes about five days for the

symptoms to appear, so there would have been a delay from

exposure to symptom formation. And perhaps we’re now

seeing relatives of those infected, and people who have been

caring for them, succumbing themselves.” The length of

2019-nCoV’s incubation period explains the sudden jump in

the number of confirmed cases. Transmission may be slowing

but cases will continue to appear due to the time it takes for

the infection to present. Ensuring China has sufficient

capacity to deal with the cases that are still to appear is why

it’s currently rushing to build new hospitals.

WHY IS THERE SUCH A WIDE MARGIN OF ERROR?

The wide margin for error associated with WHO’s estimate 2

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