Africa has been declared free from wild polio, a historic milestone that was announced Tuesday by the World Health Organization (WHO).

“Today we come together to rejoice over a historic public health success, the certification of wild poliovirus eradication in the African region,” Tedros Adhanom Ghebreyesus, director-general of the World Health Organization, said during a livestreamed event according to CNN.

Polio was once a common virus, and 25 years ago, it paralyzed thousands of children in Africa. Initial symptoms include fever, fatigue, vomiting and stiffness of the neck. Among the people paralyzed by the disease, 5 to 10% die when their breathing muscles become immobilized, the BBC reported.

Nigeria is the last country to be declared free from wild polio, after once accounting for more than half of all global cases less than a decade ago. (RELATED:US Health Secretary Alex Azar To Make Highest-Level Visit To Taiwan In Decades, A Move Likely To Anger China)

“The end of wild polio in Africa is a great day,” Tedros continued. “Your success is the success of the world. None of us could have done this alone.”

Polio is transmitted usually through contaminated water and can lead to paralysis by attacking the nervous system. More than 95% of Africa’s population has now been immunized, and only the vaccine-derived polio virus remains on the continent, with 177 cases in 2020, the BBC reported.

A vaccine-derived poliovirus means that the weakened virus used to make the oral vaccine can sometimes survive in under-immunized populations, and if it circulates long enough, it can become dangerous. 

Despite the risk of vaccine-derived poliovirus, however, WHO says that risk pales in significance to “the tremendous public health benefits associated with the oral polio vaccine.”

“Circulating vaccine-derived polioviruses in the past have been rapidly stopped with 2-3 rounds of high-quality immunization campaigns. The solution is the same for all polio outbreaks: immunize every child several times with the oral vaccine to stop polio transmission, regardless of the origin of the virus,” WHO said.

US Health and Human Services Secretary Alex Azar congratulated Africa on the accomplishment.

 ”Today is a historic day for global health, and it’s a cause for celebration for everyone who works to improve Africans health,” Azar said in a pre-recorded message. “Congratulations to everyone who helped make it possible.”