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A leading medical journal says the world could boost its blood supply from young donors by tapping into social networks like Facebook.
In an editorial last week, the Lancet calls for doctors to encourage young people to donate blood, including recruitment drives on Facebook or running advertisements for national blood donation agencies on Google.
Blood transfusions save millions of lives every year, but demand far outstrips supply.
This year, the World Health Organisation has decided to focus on young donors in its search for blood, with the slogan "new blood for the world".
By recruiting young people to donate, officials hope they will then give blood regularly in the future.
"By recruiting a new generation of those in their late teens or 20s, the hope is to boost supplies of blood from a healthy pool of donors, who will then continue to give blood regularly all year round," Lancet's editorial said.
It suggested blood donor rates could be improved by campaigns at universites or by Google carrying free advertisements for national blood donor organisations, for example.
"If every blood donor used their Facebook wall to recruit friends ... the mismatch between demand and supply could be eliminated."