Pandemic H7N9 flu would probably be much like a nuclear bomb exploding, not much you can do about except not to be around when it goes off.

The disease vector is other folks. Staying away from the crowds is the key so just bug out to areas where there isn't any other folks. Planning for 3+ to 6 months at the BOL would be probably be required.

Getting out of the City could prove to be difficult though when marshal law restrictions to movement are enforced.