Do you ever feel in a strange position because you're a woman in a male-dominated field?
It's more the reaction of other people. When I say, "I'm a scientist," you can see them blinking. I did an outreach event at a school in Camden, where I dressed up as a scientist and explained the whole point of science and a girl said to me, "Wow -- you're a woman and you're a scientist!" And that's in London.
How did you get involved in Aids research?
In a roundabout way, because I trained as a neuroscientist. I enjoyed it and yet there was always a niggle that I wanted to interact with women and children and be out in the field.
So what's your job description now?
I'm an epidemiologist, working as a consultant for a children's foundation.
You've been involved with antimicrobial gels to combat HIV. Why are they important?
It's almost a kind of chemical condom that will allow women to protect themselves against HIV but also keep options open for them. So if they want to have babies they could do so with far less risk of catching HIV, because most women catch HIV in long-term relationships and they can't always negotiate condom use. It gives women that agency in their lives.
And when you talk about your fieldwork, which countries have you been to?
Uganda, Tanzania, Zambia, Mozambique. I've done a lot of work in South Africa. That's where the burden, the bulk, of the epidemic is.
What's that experience like?
You don't get that many African women travelling around on their own, staying in hotels, so people often come up to me and ask me what I'm doing. I went through Johannesburg [airport] so often that I got to know some of the people there. There was a woman and I told her what I do. I noticed she didn't look very well. She said: "I have a friend who might have HIV. Is it true people die of that?" I said yes but it doesn't need to happen now; tell your friend to go to the hospital for drugs. A couple of months later, I walked through the airport and saw her and she looked so well. We had this interaction and I just hugged her. It was as if I knew her.
Because presumably the drugs were for her?
Yeah, it was a way of having the conversation with her. And when you see that, you see the fruits of the research.
Did any other individuals you met stand out?
The community stood out. You ask the women why they do this and they come out with all sorts of reasons. One of them might say: "I'm doing it for my sisters and my children."
Why are we so bad at dealing with Aids?
It requires a lot of commitment. It requires an investment. It goes beyond an election term. The time and effort haven't quite matched up to the scale of the problem.
Have we avoided an "Aids epidemic" by making HIV manageable rather than fatal?
There are countries such as Zimbabwe, which is where I'm from, where you can see declines in the epidemic because fewer people are getting [infected]; more people are getting treatment. But we can treat HIV yet we can't cure it. We need to find new methods of prevention.
What was life like in Zimbabwe?
I grew up there until I was 17, then I came to the UK to do my studies and I stayed. I went to a convent school; most girls didn't do science. When I was at school, I loved history and all these other subjects. I remember one of the nuns saying to me, "You're good at science, so you must do science." And my parents always encouraged me.
How is the situation in Zimbabwe now?
Things are in flux. People are hopeful that it will get better. In terms of HIV, I think it's a good sign that fewer people are dying than five years ago but it's anybody's guess what's going to happen next.
Since your marriage to the Channel 4 News presenter Jon Snow, has the focus on your personal life overshadowed your work?
Only in the past year, because if you'd googled me ten months ago, you'd have seen all my professional stuff. But when I'm interacting with people, it doesn't come up. Perhaps they're all very polite and don't mention it. I don't google myself so I don't know.
Will you always be a scientist?
Yes, but what sort of science I'll be doing in ten years' time, I don't know.
Is there anything you'd like to forget?
Loads. But when you try to forget something, you remember it.
Are we all doomed?
No. Saying we're all doomed is fatalistic and, by nature, I'm an interventionist. If I think something is not going well, there must be a way of fixing it: that's my approach to life.
1974 Born in Bulawayo, Zimbabwe
1998 Gains first-class degree in neuroscience at Edinburgh University
2003 Is awarded PhD in neuroscience at Cambridge University, where she captained the women's karate team
2005 Starts work for the Medical Research Council, focusing on HIV/Aids
2008 Becomes a Yale World Fellow
2011 Joins the Children's Investment Fund Foundation