"The sudden outbreak of a lethal virus that spreads quickly, killing millions, is a nightmare scenario that haunts many of us - especially those who have been watching BBC One's apocalyptic new drama Survivors.
Viruses have indeed wiped out 90 per cent of a human population. We've seen that in the Democratic Republic of Congo in 1976 with Ebola, an unspeakably nasty affliction caused by a haemorrhagic fever virus that has one of the highest case fatality rates of any human disease. It's one of a family of viruses that you definitely don't want to have, which also includes those responsible for Lassa fever and Marburg fever. But this event did take place in a very isolated area in a small population, with almost no access to medical help.
The lethality of these viruses limits their spread. People become so ill so quickly that they cannot travel far before dying. Ah yes, you say, (if you are the scriptwriter of Survivors), but what if someone boarded an aircraft immediately after infection but before symptoms appeared. Couldn't they spread it halfway across the world and kill 90 per cent of the population that way? No. Sorry to be a Survivors killjoy, but these viruses are pretty much stopped in their tracks by effective isolation and infection-control measures.
On the other hand, a candidate for a really good apocalypse virus is one that can be transmitted by droplet infection in the air, is infectious before a person has any symptoms and is not so lethal that people who have it can't spread it about by travelling. Something like flu, for instance. Pandemic flu is perfect.So would - could - pandemic flu wipe out 90 per cent of the population?
Categorically not, and for a number of reasons. One is logistics. You can't infect everyone at the same time, which means that we would have warning of potential infection and could prepare against it."