Wendy Zuckerman

After the cruise ship travellers were brought back to the States, his team went back and asked them a bunch of questions.

Like, soon after you were tested, did you have symptoms?

So, we started with around 50% who seemed to be asymptomatic.

Where did we land?

So that drops the number from 50 to 20%.

A pretty big drop.

And while Mateus' study just looked at the Americans on the Diamond Princess cruise, other researchers used models to expand this out to the other passengers from other countries.

And they got similar figures, estimating that now 18% were truly asymptomatic.

So for now, the evidence suggests that most people who get this virus will go on to get symptoms.

And the best study we have, this Diamond Princess study, suggests that the number of people who won't is maybe 20%.

A caveat here is that a lot of people on that cruise ship were older folks, the cruise-loving crowd, which means that we don't know if this 20% figure applies across the board.

It's possible that the younger, not so cruise-loving crowd could be more likely to be asymptomatic.

And there is another wrinkle to this story.

Research is starting to pop up to suggest that while some asymptomatic people may feel fine...

they might not be perfectly healthy.

Doctors are noticing that when hospitals actually scan these people's lungs, sometimes they don't look quite normal.

Vivek, who we heard from earlier, said, for example, doctors are finding this when people come into the hospital for something else, like, say, a broken arm.

A few small studies have found this kind of thing, like one study of 18 asymptomatic patients found seven of them had gunk in their lungs.

So that means even when people don't feel sick, the virus still might be causing trouble in their bodies.

All right, so what does this all mean for us now?