The CDC is now recommending that you have a 2 week stock of food and medicine because of the H1N1. http://www.cdc.gov/swineflu/
That is a good START, but I would recommend more than that. First of all, this flu is lasting longer than 2 weeks, and if a family gets it, they do not all stop and start at the same time. This pantry of groceries will mean that someone has to go out sick to pick up more, which will spread the virus.
However, if that is what you can do, please do so and quickly!
Now, for my personal recommendation....
Pandemics generally come in waves lasting about 6 weeks long. They usually have three waves. In 1918 the first wave was mild, but the second wave was very severe. The CDC says to expect this flu to wane in the summer then re-ignite in the fall. I would use this summer to make a nice pantry for yourself, have ways to manage if there is no electricity or clean water, start a garden, or have the supplies to grow things in your windowsill, etc.
If this flickers out, no harm--you can take the money you will have left over at the end of the month in the fall from not having to buy groceries and you can treat the family to something. You can still eat the food--it will not go bad if there is no pandemic. Gardening is a healthful hobby that encourages sustainable living and Christian stewardship. Adding "camping skills" such as how to purify water and how to cook over a fire are just general good knowledge items.
There is no loss if you prepare MORE. There could be a great loss if you are underprepared. There is a tendency to prepare in fear--it happens to all of us when we think our families could be in danger. However, we are not called to fear. We are given a sound mind, and a sound mind recognizes that things happen and it is wise to prepare for them. We UNDERSTAND that this does not come from us, but from the Lord--it is He who allows us to have provision, to gather when it is sunny for the times when it is rainy. He is our Provider, we just have this opportunity to take advantage of it.