The U.N. health agency and some major partners have agreed to send 1 million doses of cholera vaccine to Yemen to help stanch a spiraling and increasingly deadly caseload in the impoverished country, which is already facing war and the risk of famine.

A spokesman for the World Health Organization said Wednesday that it didn't initially want to publicize last week's decision because questions remain about when and how the doses could reach the neediest people in a country sliced up along front lines and grappling with a nearly-collapsed health system.

WHO said the 1 million doses for Yemen were approved on June 15 by the International Coordinating Group, which manages vaccine stocks and includes the Red Cross, Doctors Without Borders, UNICEF, and Gavi, the Vaccine Alliance along with WHO. Such a shipment would be the largest since 1 million doses were sent to Haiti after Hurricane Matthew last fall - and would amount to about half of the usual world stockpile, which would then be replenished.

In just over two years, violence from Yemen's war involving Shiite rebels known as Houthis and the internationally recognized government backed by a Saudi-led alliance has killed over 10,000 civilians. Now, in just over two months, the cholera outbreak has taken over 1,100 lives and the caseload is rising, with peak levels unpredictable, WHO says.

Vaccines will be but part of a complex response effort.

"The fact that over a thousand people have died during this rapidly spreading cholera outbreak is shocking," said Dr. Seth Berkley, CEO of Gavi, in an e-mail. "We cannot underestimate the huge logistical challenges of delivering vaccines in a warzone where the health system, as well as basic infrastructure, has been all but destroyed."

Berkley said the doses could help slow the spread of the disease as part of a broader strategy to contain it.

-AP