Vaccine wastage in Nigeria: An assessment of wastage rates and related vaccinator knowledge, attitudes and practices.

Introduction: The introduction of new vaccines highlights concerns about high vaccine wastage, knowledge of wastage policies and quality of stock management. However, an emphasis on minimizing wastage rates may cause confusion when recommendations are also being made to reduce missed opportunities to routinely vaccinate children. This concern is most relevant for lyophilized vaccines without preservatives [e.

Spatial Dynamics and High Risk Transmission Pathways of Poliovirus in Nigeria 2001-2013.

The polio eradication programme in Nigeria has been successful in reducing incidence to just six confirmed cases in 2014 and zero to date in 2015, but prediction and management of future outbreaks remains a concern. A Poisson mixed effects model was used to describe poliovirus spread between January 2001 and November 2013, incorporating the strength of connectivity between districts (local government areas, LGAs) as estimated by three models of human mobility: simple distance, gravity and radiation models. Potential explanatory variables associated with the case numbers in each LGA were investigated and the model fit was tested by simulation.

Characteristics of persons refusing oral polio vaccine during the immunization plus days - Sokoto, Nigeria 2011.

Introduction: Nigeria, the only African country endemic for wild poliovirus, adopted Immunization Plus Days (IPD) to eradicate polio. Refusal of oral polio vaccine (OPV) by heads of households is a significant challenge. In Sokoto state, we determined characteristics of heads of households refusing OPV during IPD in 2011.

Determinants of routine immunization coverage in Bungudu, Zamfara State, Northern Nigeria, May 2010.

Introduction: Immunization is a cost-effective public health intervention to reduce morbidity and mortality associated with infectious diseases. The Nigeria Demographic and Health Survey of 2008 indicated that only 5.4% of children aged 12-23 months in Bungudu, Zamfara State were fully immunized.

Using geographic information systems to track polio vaccination team performance: pilot project report.

The application of geospatial data to public health problems has expanded significantly with increased access to low-cost handheld global positioning system (GPS) receivers and free programs for geographic information systems analysis. In January 2010, we piloted the application of geospatial analysis to polio supplementary immunization activities (SIAs) in northern Nigeria. SIA teams carried GPS receivers to compare hand-drawn catchment area route maps with GPS tracks of actual vaccination teams.

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.

Key issues in the persistence of poliomyelitis in Nigeria: a case-control study.

Background: The completion of poliomyelitis eradication is a global emergency for public health. In 2012, more than 50% of the world's cases occurred in Nigeria following an unanticipated surge in incidence. We aimed to quantitatively analyse the key factors sustaining transmission of poliomyelitis in Nigeria and to calculate clinical efficacy estimates for the oral poliovirus vaccines (OPV) currently in use.

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.

Multiple independent emergences of type 2 vaccine-derived polioviruses during a large outbreak in northern Nigeria.

Since 2005, a large poliomyelitis outbreak associated with type 2 circulating vaccine-derived poliovirus (cVDPV2) has occurred in northern Nigeria, where immunization coverage with trivalent oral poliovirus vaccine (tOPV) has been low. Phylogenetic analysis of P1/capsid region sequences of isolates from each of the 403 cases reported in 2005 to 2011 resolved the outbreak into 23 independent type 2 vaccine-derived poliovirus (VDPV2) emergences, at least 7 of which established circulating lineage groups. Virus from one emergence (lineage group 2005-8; 361 isolates) was estimated to have circulated for over 6 years.

Measles resurgence following a nationwide measles vaccination campaign in Nigeria, 2005-2008.

Introduction: From 1990 through 2008, routine immunization coverage of measles vaccine in Nigeria ranged from 35% to 70%. Nigeria conducted a nationwide measles vaccination campaign in 2 phases during 2005-2006 that targeted children aged 9 months to 14 years; in 2008, a nationwide follow-up campaign that targeted children aged 9 months to 4 years was conducted in 2 phases. Despite these efforts, measles cases continued to occur.

Outbreak of type 2 vaccine-derived poliovirus in Nigeria: emergence and widespread circulation in an underimmunized population.

Wild poliovirus has remained endemic in northern Nigeria because of low coverage achieved in the routine immunization program and in supplementary immunization activities (SIAs). An outbreak of infection involving 315 cases of type 2 circulating vaccine-derived poliovirus (cVDPV2; >1% divergent from Sabin 2) occurred during July 2005-June 2010, a period when 23 of 34 SIAs used monovalent or bivalent oral poliovirus vaccine (OPV) lacking Sabin 2. In addition, 21 "pre-VDPV2" (0.

Implications of a circulating vaccine-derived poliovirus in Nigeria.

Background: The largest recorded outbreak of a circulating vaccine-derived poliovirus (cVDPV), detected in Nigeria, provides a unique opportunity to analyze the pathogenicity of the virus, the clinical severity of the disease, and the effectiveness of control measures for cVDPVs as compared with wild-type poliovirus (WPV).

Methods: We identified cases of acute flaccid paralysis associated with fecal excretion of type 2 cVDPV, type 1 WPV, or type 3 WPV reported in Nigeria through routine surveillance from January 1, 2005, through June 30, 2009. The clinical characteristics of these cases, the clinical attack rates for each virus, and the effectiveness of oral polio vaccines in preventing paralysis from each virus were compared.

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.