Will the Wuhan virus become a pandemic?
Probably. But public health services can help determine how severe it turns out to be
TWO THINGS
explain why a new infectious disease is so alarming. One is that, at
first, it spreads exponentially. As tens of cases become hundreds and
hundreds become thousands, the mathematics run away with you, conjuring
speculation about a health-care collapse, social and economic upheaval
and a deadly pandemic. The other is profound uncertainty. Sparse data
and conflicting reports mean that scientists cannot rule out the worst
case—and that lets bad information thrive.
So it is with a new coronavirus, known as 2019-nCoV,
which has struck in China. The number of reported cases grew from 282
on January 20th to almost 7,800 just nine days later. In that time four
reported cases outside mainland China have multiplied to 105 in 19
territories. Doubt clouds fundamental properties of the disease,
including how it is passed on and what share of infected people die.
Amid the uncertainty, a simulation of a coronavirus outbreak by Johns
Hopkins University in October, in which 65m people lost their lives, was
put about as a prediction. It is not.
Those
are the right questions, though: will the new virus become a global
disease? And how deadly will it be? A definite answer is weeks or months
away, but public-health authorities have to plan today. The best guess
is that the disease has taken hold in China (see article)
and there is a high risk that it spreads around the world—it may even
become a recurrent seasonal infection. It may turn out to be no more
lethal than seasonal influenza, but that would still count as serious
(see article).
In the short term that would hit the world economy and, depending on
how the outbreak is handled, it could also have political effects in
China.
The outbreak began in December.
The repeated mingling of people and animals in China means that viral
mutations that infect humans are likely to arise there; and mass
migration to cities means that they are likely to spread between people.
This virus probably originated in bats and passed through mammals, such
as palm civets or ferret badgers, ending up in Wuhan’s wet market,
where wild animals were on sale. Symptoms resemble flu, but can include
pneumonia, which may be fatal. About 20% of reported cases are severe,
and need hospital care; about 2% of them have been fatal. As yet, there
is no vaccine or antiviral treatment.
The
greatest uncertainty is how many cases have gone unrecorded. Primary
health care is rudimentary in China and some of the ill either avoided
or were turned away from busy hospitals. Many more may have such mild
symptoms that they do not realise they have the disease. Modelling by
academics in Hong Kong suggests that, as of January 25th, tens of
thousands of people have already been infected and that the epidemic
will peak in a few months’ time. If so, the virus is more widespread
than thought, and hence will be harder to contain within China. But it
will also prove less lethal, because the number of deaths should be
measured against a much larger base of infections. As with flu, a lot of
people could die nonetheless. In 2017-18 a bad flu season saw symptoms
in 45m Americans, and 61,000 deaths.
Scientists
have started work on vaccines and on treatments to make infections less
severe. These are six to 12 months away, so the world must fall back on
public-health measures. In China that has led to the biggest quarantine
in history, as Wuhan and the rest of Hubei province have been sealed
off. The impact of such draconian measures has rippled throughout China.
The spring holiday has been extended, keeping schools and businesses
closed. The economy is running on the home-delivery of food and goods.
Many experts praise China’s efforts. Certainly, its scientists have coped better with the Wuhan virus than they did with SARS
in 2003, rapidly detecting it, sequencing its genome, licensing
diagnostic kits and informing international bodies. China’s politicians
come off less well. They left alone the cramped markets filled with wild
animals that spawned SARS. With the new virus, local
officials in Wuhan first played down the science and then, when the
disease had taken hold, enacted the draconian quarantine fully eight
hours after announcing it, allowing perhaps 1m potentially infectious
people to leave the city first.
That
may have undermined a measure which is taking a substantial toll.
China’s growth in the first quarter could fall to as little as 2%, from
6% before the outbreak. As China accounts for almost a fifth of world
output, there will probably be a noticeable dent on global growth.
Though the economy will bounce back when the virus fades, the reputation
of the Communist Party and even of Xi Jinping may be more lastingly
affected (see article).
The party claims that, armed with science, it is more efficient at
governing than democracies. The heavy-handed failure to contain the
virus suggests otherwise.
Outside China
such quarantines are unthinkable. The medical and economic cost will
depend on governments slowing the disease’s spread. The way to do this
is by isolating cases as soon as they crop up and tracing and
quarantining people that victims have been in contact with—indeed, if
the disease burns out in China, that might yet stop the pandemic
altogether. If, by contrast, that proves inadequate, they could shut
schools, discourage travel and urge the cancellation of public events.
Buying time in this way has advantages even if it does not completely
stop the disease. Health-care systems would have a greater chance to
prepare for the onslaught, and to empty beds that are now full of people
with seasonal flu.
Despite all those
efforts the epidemic could still be severe. Some health systems, in
Africa and the slums of Asia’s vast cities, will not be able to isolate
patients and trace contacts. Much depends on whether people are
infectious when their symptoms are mild (or before they show any at all,
as some reports suggest), because such people are hard to spot. And
also on whether the virus mutates to become more transmissible or
lethal.
The world has never responded as rapidly to a disease as it has to 2019-nCoV.
Even so, the virus may still do great harm. As humans encroach on new
habitats, farm more animals, gather in cities, travel and warm the
planet, new diseases will become more common. One estimate puts their
cost at $60bn a year. SARS, MERS, Nipah, Zika, Mexican swine flu: the fever from Wuhan is the latest of a bad bunch. It will not be the last. ■
This article appeared in the Leaders section of the print edition under the headline "Will the Wuhan virus become a pandemic?"
No comments:
Post a Comment