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The Economist April 25th 2020
2 scription-polymerase chain reaction (rt-
pcr). This starts by sticking a q-tip-like
swab deep into the nose or throat of the in-
dividual to be tested, to retrieve a sample of
mucus that may or may not contain the vi-
rus. This sample is then run through a pro-
cess (reverse transcription) that copies any
fragments of viral rna (the molecule in
which sars-cov-2’s genes are written) into
dna, a chemical more easily handled by es-
tablished testing methods. These first am-
plify the quantity of dna present (the po-
lymerase chain reaction), and then run it
through a detector to find out what it is.
Other tests, which look for antibodies pro-
duced when someone comes into contact
with the virus, are being devised as well.
These will also be able to find out who has
been infected in the past.
The number of tests of all kinds that
America needs in order to lift its lockdown
safely is a matter of debate. Plans floated in will need big, new labs on the scale of the
recent weeks by various think-tanks have
come up with vastly different figures. All
are large. That by a working group at the Ed- thousands of tests a day, using robotics and
mond J. Safra Centre for Ethics at Harvard
University, published on April 20th, sug-
gests America will need to test between 5m
and 20m people per day, which is 2-6% of
the population. Another, put forward on
April 21st by experts convened by the
Rockefeller Foundation, outlines ideas
that could get America to 30m tests per
week in eight months’ time.
Ignition sequence start
That would not be easy. By the time this
edition of The Economist is published,
America will have carried out more than
4.5m sars-cov-2 tests since it began the
process in February. Over the first two
weeks of April, the average number of tests
per day was around 1m a week. The country
has struggled to get to even this level of
testing, so expanding it ten or 100 times
will be a big challenge.
The Rockefeller plan suggests current
testing numbers in America can be tripled
by bringing into the programme laboratory
capacity that exists already, but which is
not being used. That would involve identi-
fying all American high-throughput lab-
oratories that can be adapted for the task,
sorting out the regulatory approvals they
will need and stumping up the money.
Some states are already doing this.
Those with big research universities, such
as Massachusetts (home to Harvard and the
Massachusetts Institute of Technology,
mit, among others), have an advantage
here. The Broad Institute, a joint mit-Har-
vard enterprise run by Eric Lander, one of
the leaders of the Human Genome Project,
has begun doing sars-cov-2 tests and
might, when up to speed, be able to manage
to do 1m of them a day. In other places com-
mercial laboratories could be put to the
task. In Wisconsin Exact Sciences, a firm
that specialises in cancer tests, has rejigged
a large part of its laboratory to process
20,000 covid-19 tests a week.
Making more use of so-called point-of-
care machines would be another way to in-
crease testing capacity. These small boxes
are already used to test for viruses in thou-
sands of hospitals and clinics around the
world, and adapted versions have recently
been introduced to detect sars-cov-2.
Point-of-care machines can process throat
swabs in around 15-30 minutes. Ramping
up production of them would be useful in
bringing testing capacity to, say, rural areas
where collecting and returning throat
swabs to a big central laboratory might take
too long. The supply chains for electronics
and reagents for these machines, however,
rely heavily on China, and so building more
of them now might not be easy.
The jump from 3m tests per week to 30m
Broad to be dotted around the country.
Each of these would process hundreds of
automation. Testing needs to become sim-
pler, too. Collecting samples for rt-pcr
tests is invasive, and the tests themselves
are complicated. Scaling the process up to
millions a day is an “impossible” mission
according Severin Schwan, the boss of
Roche, a Swiss pharmaceutical giant that
makes point-of-care testing machines.
Other testing methods are possible, but
as yet unproven. Scientists at Rutgers Uni-
versity in New Jersey recently demon-
strated a way to look for signs of the virus in trained experts—and in some states such
spit samples (which are easy to obtain) in-
stead of throat swabs (which are notorious-
ly difficult and uncomfortable to collect).
On April 13th America’s Food and Drug Ad-
ministration (fda) granted spit tests an
emergency-use authorisation. Generic spit
kits that can be tweaked to do this are al-
ready widely available and can be tran-
Better safe than sorry
Science & technology 71
Combing through haystacks
Tests per confirmed case of covid-19
To April 21st 2020*, log scale
1 10 100 1,000
Vietnam
Taiwan
New Zealand
Australia
South Korea
Russia
South Africa
India
Iceland
Canada
Germany
Japan
Philippines
Italy
Sweden
Indonesia
United States
Britain
Ecuador
Source: Our World In Data *Or latest available
sported to processing laboratories at ambi-
ent temperatures.
All this new testing infrastructure will
require trained people to run it, says Scott
Becker of America’s Association of Public
Health Laboratories. Much of the handling
of samples in laboratories is routine stuff,
so people can be trained quickly to do it.
But analysing the results needs highly
people must be licensed, too. Those an-
alysts who currently exist are already put-
ting in extended shifts, says Mr Becker, and
this cannot be sustained over a pandemic
that will be “a long, long haul”.
Swabbing the noses or throats—or even
collecting the spittle—of millions of peo-
ple a day would also require a huge number
of new hires. For now, teams from Ameri-
ca’s National Guard have been helping with
that in outbreak hotspots, such as some
prisons, and at drive-through testing sites.
And then there are the 300,000 contact-
tracers that America would need, accord-
ing to another group of experts who as-
sessed that matter recently, to get in touch
with those who have been in recent prox-
imity to people who test positive. New con-
tact-tracers can, however, be trained in a
day, so lots of those who have suddenly
found themselves without a job might be
redeployed as such. San Francisco, for ex-
ample, has put librarians to the task. The
thousands of members of America’s Peace
Corps who have had to return from duty
abroad because of the pandemic might also
usefully be deployed for this purpose.
The supply of reagents and components
needed to run millions of tests a day must
be secured, too. Until now, one of the main
obstacles to their mass production has 1