Quote from the 'Avian Influenza Preparedness' webpage at the US Embassy in
Tunisia.
http://tunis.usembassy.gov/avian_influenza.html

"...The U.S. Department of State is recommending that its overseas employees
and their families prepare for the possibility of "sheltering in place" for
an extended period of time - up to twelve weeks..."

NOTE - U.S. Embassies around the world have offered similar advice, even if
some have since changed the 12 weeks to 2 weeks. Do a Google search to
confirm whether or not the Embassy/Consulate in YOUR country is advising the
3 months/12 weeks supply or not.

...And should you think the '12 weeks' bit is a typographical error of '2
weeks'...

Quote from the 'Ambassador's letter To American Citizens' webpage of the US
Consulate in Vietnam...
http://hochiminh.usconsulate.gov/letter.html

"...All staff and families have been advised to stockpile non-spoilable food
and safe water for up to a month, in case there is need to remain at home in
social isolation..."

Rhetorical Question - How much have you got stored away for you and yours?

Some clarification re time to stokpile for in this message from the US
Embassy In
Ottawa, Canada...

http://ottawa.usembassy.gov/content/textonly.asp?section=issues&document=avi
an_influenza_advice

"...Depending on the severity of a pandemic, commercial airlines might
drastically curtail or even cease operations. Travel restrictions could also
impede people from returning to the U.S. or fleeing to other countries. For
these reasons, it may make more sense to shelter-in-place (i.e., stay home
and practice "social distancing" to avoid contagion) for a period of
time..."

The message goes on to define two different 'stockpiling situations'...

"...U.S. Residents: The Department of Health and Human Services suggests
that U.S. residents prepare emergency supplies (food, water, medicines,
etc.) to shelter-in-place for two weeks during an influenza pandemic..."

"...American Citizens Abroad: Due to varying conditions overseas, Americans
abroad should evaluate their situation and prepare emergency supplies (food,
water, medicines, etc.) to shelter-in-place for at least two and up to
twelve weeks..."