There also is the issue that we have a massive global shortage, right now the people most at risk from this virus are frontline health workers who are exposed to the virus every second of every day. The thought of them not having masks is horrific.

Mike Ryan

Obviously, there are many people around the world who are very sick with this disease and we want to ensure that everybody has access to the necessary lifesaving interventions, we are fully committed as an organization, and with our partners to equitable access to life saving interventions.

It is exceptionally important in this case, that the drug is reserved for use in severely ill and critical patients who can benefit from this drug clearly.

I'm absolutely convinced that that is occurring. The question is how much.

Whatever proportion of disease is transmitting from asymptomatic individuals, as Maria said, that is unknown, i'm absolutely convinced that that is occurring. The question is how much.

Let me also emphasize, if you are sick with a fever, with a cough and are sneezing, you should not be in public, you should be seeking the care of a medical professional and seeking a Covid-19 test, we need to be very, very, very careful that masks are not seen as an alternative to the other public health measures that are so desperately needed.

South America has become a new epicentre of the disease.

We don't know what the impact of this will be in undernourished children with chronic malnutrition, we don't know what the impact of this will be in in overcrowded refugee camps. So, there's a lot still to be learned.

This virus just may become another endemic virus in our communities and this virus may never go away. HIV hasn't gone away, i'm not comparing the two diseases but I think it is important that we're realistic. I don't think anyone can predict when or if this disease will disappear.

This idea that... so what if we lose a few old people along the way ? This is a really dangerous, dangerous calculation.

We will be engaging in discussions with Gilead and the U.S. government as to how this drug may be made more widely available as further data emerges on its effectiveness.

We are very, very keen to stress that IT tools do not replace the basic public health workforce that is going to be needed to trace, test, isolate and quarantine.

So if that data and evidence is available, then it will be for the United States government to decide whether and when it can be shared.

The scientific question is, ´To what extent does having had that infection offer you protection against another infection?' that is the question that still needs to be addressed.

Many people are asking, 'Well why do we have to test the vaccines? Why don't we just make the vaccines and give them to people?' Well the world has learned many lessons in the mass use of vaccines and there's only one thing more dangerous than a bad virus, and that's a bad vaccine, we have to be very, very, very careful in developing any product that we're going to inject into potentially most of the world population. We have to be very, very, very careful that we first do no harm. So that's why people are being careful.

A lot of preliminary information coming to us right now would suggest quite a low percentage of population have seroconverted (to produce antibodies), the expectation that ... the majority in society may have developed antibodies, the general evidence is pointing against that, so it may not solve the problem of governments.

We take thousands of samples every single week, and we will continue that active surveillance right the way through.

And in that sense, maybe that's our lesson for COVID-19, there is no exit strategy until you are in control of the situation, and you must always be ready to go back again and start again.

It takes anything up to six weeks to recover from this disease, people who suffer very severe illness can take months to recover from the illness.

We have a massive global shortage, right now, the people most at risk from this virus are front-line health workers who are exposed to the virus every second of every day. The thought of them not having masks is horrific.

Saturdays I try and take time off, but then on Sunday I try to do maybe a nine - or 10-hour day.