Africa now free of wild poliovirus, but polio threat remains
FILE - In this Wednesday, April 24, 2013 file photo, a Somali baby receives a polio vaccine at the Medina Maternal Child Health center in Mogadishu, Somalia. Health authorities on Tuesday, Aug. 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (AP Photo/Ben Curtis, File)

FILE - In this Wednesday, April 24, 2013 file photo, a Somali baby receives a polio vaccine at the Medina Maternal Child Health center in Mogadishu, Somalia. Health authorities on Tuesday, Aug. 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (AP Photo/Ben Curtis, File)

Aug. 25, 2020 06:01 AM EDT
FILE - In this April 14, 2014 file photo, Hamamatou Harouna, 10, who lost the use of her legs to polio, crawls to the restroom on the grounds of the Catholic Church where she and hundreds of others found refuge after fleeing violence in her village, in Carnot, Central African Republic. Health authorities on Tuesday, Aug. 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (AP Photo/Jerome Delay, File)

FILE - In this April 14, 2014 file photo, Hamamatou Harouna, 10, who lost the use of her legs to polio, crawls to the restroom on the grounds of the Catholic Church where she and hundreds of others found refuge after fleeing violence in her village, in Carnot, Central African Republic. Health authorities on Tuesday, Aug. 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (AP Photo/Jerome Delay, File)

Aug. 25, 2020 06:01 AM EDT
FILE - In this Sunday, Aug. 28, 2016 file photo, a health official administers a polio vaccine to a child at a camp for people displaced by Islamist Extremists, in Maiduguri, Nigeria. Health authorities on Tuesday, Aug. 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (AP Photo/Sunday Alamba, File)

FILE - In this Sunday, Aug. 28, 2016 file photo, a health official administers a polio vaccine to a child at a camp for people displaced by Islamist Extremists, in Maiduguri, Nigeria. Health authorities on Tuesday, Aug. 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (AP Photo/Sunday Alamba, File)

Aug. 25, 2020 06:03 AM EDT
FILE - In this Saturday, Aug. 27, 2016 file photo, a polio campaigner smiles during a polio vaccination exercise in Maiduguri, Nigeria. Health authorities on Tuesday, Aug. 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (AP Photo/Sunday Alamba, File)

FILE - In this Saturday, Aug. 27, 2016 file photo, a polio campaigner smiles during a polio vaccination exercise in Maiduguri, Nigeria. Health authorities on Tuesday, Aug. 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (AP Photo/Sunday Alamba, File)

Aug. 25, 2020 06:04 AM EDT
FILE - In this Sunday, Aug. 28, 2016 file photo, health officials administer polio vaccine to children at a camp for people displaced by Islamist extremists in Maiduguri, Nigeria. Health authorities on Tuesday, Aug. 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (AP Photo/Sunday Alamba, File)

FILE - In this Sunday, Aug. 28, 2016 file photo, health officials administer polio vaccine to children at a camp for people displaced by Islamist extremists in Maiduguri, Nigeria. Health authorities on Tuesday, Aug. 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (AP Photo/Sunday Alamba, File)

Aug. 25, 2020 06:02 AM EDT