Nick Beeching

So you would test somebody who's infectious and test those around them.

If you then had antibody tests as well, you could test those around them to see if they've already had the infection.

So another way of, if I came into, you know, let's say a village and wanted to know who had had infection, then I would normally do an antibody testing and you'd see what proportion of the people at different ages had had infection from that test.

And you could ask them if they ever had any symptoms and work out how many

had the infection without having any symptoms.

And that's a common approach for many infections.

Well, as I said, looking for the virus, you want sensitivity, looking for the antibodies

in a sense, specificity is better.

You don't want false positives.

You want to be sure that a positive result is there.

You want it to be pretty sensitive as well, but the specificity is more important.

There are a lot of key workers, health care workers and others, people working in the community who are off work.

They're self-isolating because they might have symptoms or they might be at risk or somebody in the house has a cough.

It would be marvellous to have a blood test that said you've had this infection and we think it's safe for you to go back to work and look after other people.

There is one caveat to that is that we don't yet know.

If immunity is solid, in other words, if you've had the infection, we have a positive antibody test.

We assume that you have quite good immunity, at least in the short term.

But we won't know that, of course, until we follow people up for a few years.

But even so, it would provide me with reassurance if I had a positive antibody test that at least I had some degree of immunity.

I would return to work and I would still have to take appropriate precautions.