The number of suspected cases affected by the outbreak is now more than 325,000. Cholera
is an acute diarrheal illness which kills thousands of people worldwide each year.
"The situation has evolved so rapidly that vaccines are not the priority tool to use right now," Tarik Jasarevic, WHO spokesperson, said in an email.
"Now that cholera has spread to 91% of Yemen's governorates, the focus will instead be on scaling up other interventions that will have a greater effect on the evolution of the outbreak and save lives."
Those interventions include scaling up access to clean water and sanitation, treatment to people affected and working with communities to promote hygiene, sanitation and cholera prevention, explained Jasarevic.
The one million doses of vaccine were initially approved by the International Coordinating Group, an organization established in 1997 with the purpose of managing and coordinating the use of emergency vaccine supplies and antibiotics to countries in the midst of major outbreaks, according to WHO
Five hundred thousand doses were shipped to Djibouti in East Africa because of the country's close proximity to Yemen, Jasarevic said. The country is across the Bab al-Mandab Strait from Yemen.
The vaccines are still there, and they may be shipped to another country for use, he said.
"The decision to suspend was taken by the Yemeni authorities in consultation with the technical teams that are working on cholera from the United Nations side," said George Khoury, Head of Office at the UN Office for the Coordination of Humanitarian Affairs in Yemen.
WHO confirmed that they and other partners were consulted on the decision. They serve as advisers to the Yemen health authorities on vaccines and other interventions related to the ongoing cholera outbreak in the country, Jasarevic said.
"It was decided by the professionals that all the risks and the potential problems may outweigh the benefits of administering the vaccine," Khoury said. "Given the limited number of vaccines, administering the vaccines in some areas and not others may create disputes on who gets and who doesn't get the vaccine."
Between April 27 and July 12 of this year, there have been 326,082 suspected cholera cases and 1,743 deaths, according to a WHO statement
Children under the age of 15 make up 42% of suspected cases. Thirty-two percent of deaths have been people over the age of 60, according to WHO.
WHO, UNICEF and other partners that have been providing aid have established 2,924 diarrhea treatment centers in the country, and 711 oral rehydration therapy facilities, the WHO statement said.