16 BriefingThe pandemic The EconomistMarch 21st 2020
21France had seen 2,281 covid cases and suf-
fered 48 deaths. Six days later, on March
18th, those numbers had more than tripled,
to 9,043 and 148 respectively. In Spain they
were 13,910 and 623, in Italy 35,713 and 2,978.
Over the week to the 18th the euand Britain
acknowledged around 62,000 new cases of
covid-19, 2.6 times the number seen in the
rest of the world. Europe’s cumulative
caseload now exceeds China’s. In terms of
its rapidly evolving responses, too, Europe
seems now to lead the world. And it is lead-
ing it into lockdown.
But if general exponential whiplash was
the bulk of the explanation, in Britain a
model of the epidemic produced by epide-
miologists at Imperial College in London
played a particular role. Earlier versions
had been circulating in the corridors of
power for a while (as covid-19 may have
been doing, too; on March 18th the study’s
lead author, Neil Ferguson, isolated him-
self with a cough and a fever). Published on
March 16th, it is now proving influential
elsewhere, too.
The Imperial modellers adapted a mod-
el originally developed for influenza out-
breaks. They assumed that the time from
infection to symptoms, among those who
showed symptoms, would be about five
days; that people without symptoms
would be somewhat infectious, but less so
than people with symptoms; that people
would vary in how infectious they get.
They assigned covid-19 a “basic reproduc-
tion number” of 2.4. This means that in a
population not taking any precautions,
and where no one is immune, each case
leads, on average, to 2.4 secondary cases.
Under those conditions the model
showed the disease infecting 80% of the
British population in three to four months.
If 4.4% of the people infected became ill
enough to be hospitalised and 30% of those
deteriorated to the point of needing inten-
sive care, then by mid-April demand for
beds in intensive-care units (icus) would
outstrip the health service’s “surge” capaci-
ty. In May the number of critical patients
would be more than 30 times the number
of icubeds available. Estimates of the fatal-
ity rate in China range from 0.5% to 1.5% of
infections. Using a conservative 0.9% for
Britain, the model put the death toll by the
end of the summer at over half a million.
The 4.4% hospitalisation rate was gen-
erated by breaking figures from China
down by age cohorts and applying those
age-specific rates to Britain’s population
structure. This makes the numbers bigger.
In China only 12% of the population is over
65; in Britain the proportion is 19% (in
America, which the team also looked at, it
is 17%). In continental countries you would
expect the number to be bigger still; 23% of
Italians are over 65, as are 22% of Germans.
The model’s most striking message,
though, was not this worst-case scenario: itwas how small the effects of less-than-
wholehearted interventions appeared to
be. Imposing isolation on people with
symptoms of the disease, quarantine on
their households and protecting the elder-
ly through social distancing—broadly
speaking, the sum of British government
advice as of last week—cut the height of the
epidemic’s peak by two-thirds and pushed
it from May to June. But the demand for
beds still outstripped the supply by a factor
of eight, and the death toll still reached the
hundreds of thousands.
Extending social distancing from the
over-70s to the whole population,
though—a lockdown along the lines of Mr
Macron’s, or of what is being seen in Italy—
made a big difference. The peak of the dis-
ease outstripped the nhs’s surge capacity
by just a factor of two. And it was delayed
until July or August. That is a time-frame
over which increasing that capacity is
clearly plausible. It might also allow the
change of the seasons to nibble away at the
disease’s reproductive number.¡No pasarán!
Because cases of covid-19 have already ap-
peared in hot places such as Saudi Arabia
and Singapore—not to mention Australia,
where it is currently the end of summer—
some experts have dismissed the idea that
it may be at its worst in winter. But there re-
mains hope that the change in the seasons
may slow its spread. In early March Chi-
nese scientists circulated a preprint look-
ing at how air-temperature and humidity
influenced transmission in 100 Chinese
cities, and controlling for population den-
sity and wealth, they concluded that trans-
mission became a little less likely when the
weather was hotter and more humid. Sum-
mer and rainy seasons may not help a lot—
but they could help a bit.
The Imperial results shaped the British
government’s new plans: everyone to work
from home if they can, no travel for fun, no“unnecessary” visits to care homes, avoid
pubs, restaurants, theatres and the like,
quarantines of 14 days for households
where someone develops symptoms.
This still did not put Britain quite on a
par with its neighbours (see chart 1 on next
page). In Spain the state of emergency has
closed all schools and universities, and al-
most all non-food shops except dry-clean-
ers, pharmacies and, again, tobacconists.
The number of travellers on the Madrid
metro on March 18th was 15% of what it
usually is, and parks and promenades in
the capital are sealed off. Thousands of ma-
drileños who, given lovely weather and
clear indications of restrictions on the way,
had headed for their beach houses at the
weekend promptly found themselves con-
fined by the regional government of Mur-
cia. The state of emergency—which will
need parliamentary approval to continue
for more than 15 days—allows the govern-
ment to requisition the facilities of private
hospitals and to take over hotels, too. It has
already taken over two in Madrid.
Mrs Merkel’s guidelines of March 16th
called for most retail outlets to close and
for the shops staying open to do so on Sun-
day, when trading restrictions normally
keep almost everything shut. Bars and
clubs are closed. In Berlin police went
door-to-door in Neukölln and Kreuzberg
ordering patrons to drink up. Theatres,
concert halls, museums, cinemas, exhibi-
tion halls, gymnasiums, swimming pools
and casinos have all been closed, as have
Germany’s many legal brothels. Hairdress-
ers, though, remain open.
The hairdressers of Spain were initially
granted the same privilege, but it was re-
voked. That said, the Spanish can still go to
church services, though with precautions,
whereas Germany’s churches and mosques
are closed. The Church of England has vo-
luntarily brought an end to public worship,
too. As for secular religions, all Europe’s
major football leagues have put games onHubei
67,
5,20,1PeopleinfectedShareofcasesthat
occurredinthepast
week,%1050901000What the pandemic looks likeSource: Johns Hopkins CSSEConfirmed covid-19 cases, to March 18th 2020