What we do (and don't) know about the coronavirus | David Heymann

[As of the morning February 27, 2020,

there were at least 82,000 confirmed cases worldwide of the coronavirus

and 2,810 deaths from it.

TED invited Dr. David Heymann to share the latest findings about the outbreak.]

[What happens if you get infected with the coronavirus?]

This looks like a very mild disease, like a common cold,

in the majority of people.

There are certain people who get infected and have very serious illness;

among them are health workers.

It's a very serious infection in them,

as they get a higher dose than normal people,

and at the same time, they have no immunity.

So in the general population,

it's likely that the dose of virus that you receive when you are infected

is much less than the dose that a health worker would receive,

health workers having more serious infections.

So your infection would be less serious, hopefully.

So that leaves the elderly and those with comorbidities

to really be the ones that we have to make sure

are taken care of in hospitals.

[Who are the people who should be most concerned about this?]

Well, the most concerned are people

who are, first of all, in developing countries

and who don't have access to good medical care

and may not have access at all to a hospital,

should an epidemic occur in their country.

Those people would be at great risk,

especially the elderly.

Elderly in all populations are at risk,

but especially those who can't get to oxygen.

In industrialized countries,

it's the very elderly who have comorbidities,

who have diabetes, who have other diseases,

who are at risk.

The general population doesn't appear to be at great risk.

[What pre-existing medical conditions put people at higher risk?]

First of all,

pulmonary disease existing as a comorbidity is also important.

In general, the elderly are at greater risk,

especially those over 70,

because their immune systems are not as effective

as they might have once been,

and they are more susceptible to infections.

In addition, in some instances in China,

there's been a coinfection with influenza

and at the same time,

there have been some bacterial superinfections

on the pneumonias that are occurring.

[Where can we find up-to-date information?]

The Center for Disease Control in Atlanta keeps track

and has updates on a regular basis on its website.

Also, the World Health Organization in Geneva,

which is coordinating many of the activities

going on internationally,

also has a website with daily updates.

It's our responsibility to get that information as individuals,

so we understand

and can make sure that we can contribute in our own way

to prevention of major spread.

[You led the global response to the SARS outbreak in 2003.

How does this outbreak compare?]

That's the same problem with all new infections.

This is an infection that's coming to humans

who have never been exposed to this virus before.

They don't have any antibody protection,

and it's not clear whether their immune system

can handle this virus or not.

This is a virus that usually finds itself in bats or in other animals,

and all of a sudden, it's in humans.

And humans just don't have experience with this virus.

But gradually,

we are beginning to learn a lot, as we did with SARS.

And you know, there are certainly a larger number of deaths

than there were with SARS.

But when you divide that by a denominator of persons who are infected,

there are many, many more persons infected than there were with SARS.

The case fatality ratio,

that is the ratio of deaths to the numbers of cases in SARS,

was about 10 percent.

With the current coronavirus, COVID-19,

it is two percent or probably less.

So it's a much less virulent virus,

but it's still a virus that causes mortality,

and that's what we don't want entering human populations.

[Have we responded adequately at border crossings, such as airports?]

It's clearly understood that airports or any land borders

cannot prevent a disease from entering.

People in the incubation period can cross that border,

can enter countries

and can then infect others when they become sick.

So borders are not a means of preventing infections from entering a country

by checking temperatures.

Borders are important because you can provide to people arriving

from areas that might be at risk of having had infection,

provide them with an understanding,

either a printed understanding or a verbal understanding,

of what the signs and symptoms are of this infection,

and what they should do if they feel that they might be infected.

[What's the timeline for a vaccine?]

Vaccines are under development right now,

there's a lot of research going on.

That research requires first that the vaccine be developed,

then that it be studied for safety and effectiveness in animals,

who are challenged with the virus after they are vaccinated,

and then it must go into human studies.

The animal studies have not yet begun,

but will soon begin for certain vaccines.

And it's thought that by the end of the year,

or early next year,

there may be some candidate vaccines

that can then be studied for licensing by regulatory agencies.

So we're talking about at least a year until there's vaccine available

that can be used in many populations.

[What questions about the outbreak are still unanswered?]

It's clear we know how it transmits,

we don't know how easily it transmits in humans,

in communities or in unenclosed areas.

We know, for example,

that in the enclosed area of a cruise ship, it spread very easily.

We need to better understand

how it will spread once it gets into more open areas

where people are exposed to people who might be sick.

[What about the global response could be improved?]

A major problem in the world today is that we look at outbreaks

in developing countries

as something that we need to go and stop.

So when there's an outbreak of Ebola,

we think "How can we go and stop this outbreak in the country?"

We don't think about "How can we help that country

strengthen its capacity,

so that it can detect and respond to infections?"

So we haven't invested enough

in helping countries develop their core capacity in public health.

What we've done is invested in many mechanisms globally,

which can provide support to other countries

to go and help stop outbreaks.

But we want to see a world where every country

can do its best to stop its own outbreaks.

[Will we see more emerging disease outbreaks in the future?]

Today, there are over seven billion people.

And when those people come into the world,

they demand more food,

they demand a whole series of things

and they live closer together.

In fact, we're an urban world, where people live in urban areas.

And at the same time, we're growing more animals,

and those animals are contributing food to humans as well.

So what we see

is that that animal-human interface is becoming closer and closer together.

And this intensive agriculture of animals

and this intensive increase in human populations

living together on the same planet

is really a melting pot where outbreaks can occur and do occur.

We will eventually have more and more of these outbreaks.

So an emerging infection today is just a warning

of what will happen in the future.

We have to make sure

that that technical collaboration in the world

is there to work together

to make sure that we can understand these outbreaks when they occur

and rapidly provide the information necessary to control them.

[Is the worst behind us?]

I can't predict with accuracy.

So all I can say is that we must all be prepared

for the worst-case scenario.

And at the same time,

learn how we can protect ourselves and protect others

should we become a part of that epidemic.

[To learn more, visit: Centers for Disease Control and Prevention

World Health Organization]