Nigeria, Aug. 8 -- Under the harsh April sun, the heat was oppressive in Fagge Local Government Area of Kano State. But 56-year-old Uma Usman kept walking from one compound to another, calling out familiar names, knocking gently on half-open doors and asking after children she had come to know over the years.

She is not an employee of the local Galadima Primary Health Centre. Her name does not appear on any government payroll. Yet, she has become one of the most important links in the community's immunisation system.

Her job is to find children who missed their routine immunisation appointments.

"I know the community very well, so I follow them house by house," Mrs Usman told PREMIUM TIMES. "If the parents don't come, we check the regi...