Pneumonia struck first. Then tonsillitis spiraled into sepsis. Malaria battered him next, and after treatment, the other illnesses flared back up again. This unvaccinated 2-year-old boy is trapped in a relentless cycle.

"I was very sad. I knew these things could be prevented by vaccines," his mother Alzhraa Fadul says through an interpreter.

"I feel guilty that I can't do anything to help my son," the 26-year-old adds. "I'm worried about my son every day. I should've gotten vaccines for my son."

But there was nowhere for Fadul to get them. Her family lives in an abandoned classroom with 10 strangers in Kosti, Sudan, where vaccination campaigns were once hailed as a "remarkable achievement" and earned the country a coveted polio-free status one decade ago.

That all changed in Ap

See Full Page