GENEVA, May 7 (Xinhua) -- The World Health Organization (WHO) said Monday that the largest cholera vaccine campaign in history has been launched in Africa to help more than 2 million people in five countries to get access to oral cholera vaccine (OCV).

The vaccines, funded by Gavi, the Vaccine Alliance, were sourced from the global stockpile and are being used to carry out five major campaigns in Zambia, Uganda, Malawi, South Sudan and Nigeria.

The OCV is recommended to be given in two doses. The first gives protection for six months, the second for three to five years. All five campaigns should have completed their second round of vaccinations by mid-June.

It's the world's largest cholera vaccine drive ever, which is scheduled to use over 15 million doses in the first four months of 2018, the WHO said. In comparison, in the 15 years between 1997 and 2012, just 1.5 million doses of cholera vaccines were used worldwide.

According to the latest WHO figures, the burden of cholera remains high in many African countries.

"Every rainy season, cholera springs up and brings devastation to communities across Africa," said Dr. Matshidiso Moeti, WHO's regional director for Africa. As of May 7 many countries are facing cholera outbreaks, with at least 12 areas or countries reporting active cholera transmission in sub-Saharan Africa.

"With this historic cholera vaccination drive, countries in the region are demonstrating their commitment to stopping cholera from claiming more lives," Dr. Matshidiso Moeti said.

Though the OCV is a key weapon in the fight against cholera, many other aspects are no less important, such as, according to WHO Director-General Dr. Tedros Adhanom Ghebreyesus, clean water and sanitation, treatment centers, supplies, public health guidance, training of health workers, and working with communities on prevention.

"This is an unprecedented response to a spike in cholera outbreaks across Africa," said Gavi CEO Dr. Seth Berkley, but "the only long-term, sustainable solution to cholera outbreaks" is still "improved water and sanitation."