How to treat covid-19 | The Economist

published on July 2, 2020

As covid-19’s global impact mounts

so does the urgent need to stop its spread

A vaccine is what we need for life

to get back to some sort of semblance of normality

Scientists are working as quickly as they can

But that’s at least a year, a year-and-a-half, two years away

In the meantime scientists are trialling existing drugs

to treat covid-19

The coronavirus which causes covid-19

was only identified in January this year

A mysterious pneumonia outbreak in China has been identified

It’s from the same family that caused the deadly

SARS epidemic 17 years ago

But scientists have known about coronaviruses since the 1960s

Giving them a head start in understanding it

And that meant that when this current, new strain appeared

there was quite a lot of understanding of the basic biology

SARS-CoV-2, which is the new coronavirus, has a very similar

structure to previous coronaviruses

And by understanding the biology and structure of that virus

we can start to look for ways to attack it

The virus has an outer membrane made up of fatty molecules

which scientists call lipids

Spike proteins float on this lipid membrane

and provide the virus particle with the appearance of a crown

giving the coronavirus its name

Inside is a molecule of RNA

a chemical similar to DNA

on which the virus’s genome is written

When the virus gets inside the body

the spike proteins link up with proteins found

on the surface of cells in the lung’s airways

This lets the virus break into the patient’s cells

Inside it releases the RNA that carries the virus’s genes

Those genes hijack the cell’s protein-making machinery

to produce the building blocks for more virus particles

One specific gene called replicase

provides the instructions to build a molecular machine

that copies the virus’s RNA

making enough for up to 1,000 new virus particles

The new particles are then released from the cell

to attack other cells, spreading the virus

It’s this replicase system that has become a focus

for scientists searching for an effective treatment

The replicase system within the virus is actually a good target

for disrupting how the virus works

because healthy human cells don’t actually copy RNA within them

So, what you could do is if you could disrupt

the replicase system in the virus

you’d hopefully destroy the virus without harming human cells

But developing a new drug from scratch that could do this

and running the trials needed to ensure the drug

is safe for humans could take months or even years

During a pandemic every month you spend trying to do research

more people will potentially suffer or die

And so that’s why there’s a move to try and repurpose existing drugs

If you’ve already got a drug available for something else

you know that it’s probably safe for humans

and so you can speed up the whole process

One of the drugs seen as most promising

is called remdesivir

It was originally developed to treat Ebola

by blocking the replicase system

It was found to be safe for humans

but was shelved in favour of a more effective treatment

The molecules in remdesivir look like the molecules

that the replicase system uses to make RNA

When this drug gets into a cell

the virus tries to use the drug molecules to replicate

and then it basically doesn’t work

so the virus doesn’t manage to replicate properly

And there are other drugs on the market

that scientists believe could also make it harder

for the virus to replicate itself

There’s also another drug called Kaletra

which is used to treat HIV at the moment

in combination with other therapies

It was tried during the original SARS outbreak in 2003

and seemed to offer some benefits

What that does is target the enzymes that

chop up big proteins into smaller proteins

during the replication process of a virus

So, if you can disrupt that

perhaps that’s another way to stop it from replicating within cells

Both remdesivir and Kaletra are now being tested

as part of a global mega-trial

set up by the World Health Organisation in March

The WHO study will also put the anti-malarial chloroquine to the test

President Donald Trump has built up a lot of hype

around hydroxychloroquine, a similar drug which works in the same way

We’re going to be able to make that drug available almost immediately

Based on what I see it could be a game-changer

But the president’s enthusiasm is damagingly ill-informed

In the lab it seems chloroquine may reduce the virus particle’s ability

to get into cells and to reproduce

But in patients there is no strong evidence as yet

that the drug can treat covid-19

The WHO study should provide a definitive answer

on chloroquine and the other drugs it’s testing

What the World Health Organisation is trying to do

is speed up the process by just trialling more people

and that will hopefully allow them to pick up

even very marginal benefits of the drugs

pick up very small side-effects as well

And then using all of that information

it might just help these systems understand how to reduce

the number of days someone is infected

Reducing the number of days someone is ill for

can prove vitally important

Even very small differences in the length of time

someone’s ill can have an enormous knock-on

benefits for a health system

If you can knock five days off the amount of time

someone needs to be in hospital, or needs a ventilator

you can treat more people with the same number of ventilators

with the same number of doctors

An effective vaccine is the only definitive

way to halt the spread of coronavirus

But while the world waits for that

repurposing existing drugs could help doctors treat it

Allowing patients, health systems, and countries

that are coming under intolerable strain to find a little respite

We’re dedicated to bringing you the most up-to-date reporting

and analysis on this rapidly changing story

So, clicking on the link opposite it will take you to

all of our coronavirus coverage

Thank you for watching

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