An evaluation of polio supplemental immunization activities in Kano, Katsina, and Zamfara States, Nigeria: lessons in progress.

BACKGROUND: As 1 of 3 remaining poliovirus-endemic countries, Nigeria has become key to the global polio eradication effort. We evaluated supplemental immunization activities, including team performance, communications/mobilization activities, and vaccine acceptance, in 3 high-risk states. METHODS: We used structured survey and observation instruments, document review, and stakeholder interviews. RESULTS: Observations or surveys were conducted at 1697 households. Vaccine acceptance ranged from 87%-94%; among households rejecting polio vaccine, 38% of mothers sought measles vaccine for their children. Teams performed between 4%-42% of assigned tasks. CONCLUSIONS: Acceptance is high but teams have a critical role in surmounting residual vaccine resistance.

Effectiveness of immunization against paralytic poliomyelitis in Nigeria.

BACKGROUND: The number of cases of paralytic poliomyelitis has declined in Nigeria since the introduction of newly licensed monovalent oral poliovirus vaccines and new techniques of vaccine delivery. Understanding the relative contribution of these vaccines and the improved coverage to the decline in incident cases is essential for future planning. METHODS: We estimated the field efficacies of monovalent type 1 oral poliovirus vaccine and trivalent oral poliovirus vaccine, using the reported number of doses received by people with poliomyelitis and by matched controls as identified in Nigeria's national surveillance database, in which 27,379 cases of acute flaccid paralysis were recorded between 2001 and 2007. Our estimates of vaccine coverage and vaccine-induced immunity were based on the number of doses received by children listed in the database who had paralysis that was not caused by poliovirus. RESULTS: The estimated efficacies per dose of monovalent type 1 oral poliovirus vaccine and trivalent oral poliovirus vaccine against type 1 paralytic poliomyelitis were 67% (95% confidence interval [CI], 39 to 82) and 16% (95% CI, 10 to 21), respectively, and the estimated efficacy per dose of trivalent oral poliovirus vaccine against type 3 paralytic poliomyelitis was 18% (95% CI, 9 to 26). In the northwestern region of Nigeria, which reported the majority of cases during the study period, coverage with at least one dose of vaccine increased from 59 to 78%. Between 2005 and 2007, vaccine-induced immunity levels among children under the age of 5 years more than doubled, to 56%. CONCLUSIONS: The higher efficacy of monovalent type 1 oral poliovirus vaccine (four times as effective as trivalent oral poliovirus vaccine) and the moderate gains in coverage dramatically increased vaccine-induced immunity against serotype 1 in northern Nigeria. Further increases in coverage in Nigerian states with infected populations are required to achieve the levels of vaccine-induced immunity associated with the sustained elimination achieved in other parts of the country.

Epidemiology of rotavirus diarrhea among children younger than 5 years in Enugu, South East, Nigeria.

BACKGROUND: Severe rotavirus diarrhea in children is a major cause of morbidity globally and mortality in developing countries. It is estimated to be responsible for >453,000 deaths in children <5 years of age globally and 232,000 in the African region. The aim of the current study was to determine the prevalence of rotavirus gastroenteritis among hospitalized children <5 years of age in Enugu and to support awareness and advocacy efforts for the introduction of rotavirus vaccines in Nigeria. METHODS: World Health Organization-standardized case forms were used to collect data from eligible children with non-bloody diarrhea from October 2010 to September 2012. Data collected included socio-demographic and clinical information. Stool samples were obtained from recruited children and tested for rotavirus antigen using the Oxoid Prospect ELISA Kit (Basingstoke, United Kingdom). RESULTS: Of the 615 diarrhea stool samples collected, 344 (56%) were positive for human rotavirus. Of the 344 positive samples, 329 (96%) were children <2 years of age, while 247 (77%) were <1 year of age. Peak rotavirus season occurred during the cold dry months of December to April during which 95% of all cases occurred. CONCLUSIONS: This study found a relatively high incidence of severe rotavirus-associated diarrhea disease in Nigeria and infants were the most affected. It highlights the urgent need for introduction of rotavirus vaccine into the national immunization program and the need to adequately equip health facilities to enable them administer intravenous fluids to severe diarrhea patients to reduce morbidity and mortality.