There are too many unknowns at the moment, and a nice outbreak of porcine flu would send already jittery markets all over the shop. I see the airlines are already taking a battering off the back of it - down 10% today already.
I trade emerging market indices, and they don't trade even 24 hours during the week. There's great profit potential, but I've already decided to go flat for a day or two until the impact of the latest round of news has settled in. I know it's a slim possibility, but if we have a major pandemic which infects the UK, at the very least there will be rabid panic, nevermind actual casualties.