Clustered lot quality assurance sampling: a pragmatic tool for timely assessment of vaccination coverage.

OBJECTIVES: To evaluate oral poliovirus vaccine (OPV) coverage of the November 2009 round in five Northern Nigeria states with ongoing wild poliovirus transmission using clustered lot quality assurance sampling (CLQAS). METHODS: We selected four local government areas in each pre-selected state and sampled six clusters of 10 children in each Local Government Area, defined as the lot area. We used three decision thresholds to classify OPV coverage: 75-90%, 55-70% and 35-50%. A full lot was completed, but we also assessed in retrospect the potential time-saving benefits of stopping sampling when a lot had been classified. RESULTS: We accepted two local government areas (LGAs) with vaccination coverage above 75%. Of the remaining 18 rejected LGAs, 11 also failed to reach 70% coverage, of which four also failed to reach 50%. The average time taken to complete a lot was 10 h. By stopping sampling when a decision was reached, we could have classified lots in 5.3, 7.7 and 7.3 h on average at the 90%, 70% and 50% coverage targets, respectively. CONCLUSIONS: Clustered lot quality assurance sampling was feasible and useful to estimate OPV coverage in Northern Nigeria. The multi-threshold approach provided useful information on the variation of IPD vaccination coverage. CLQAS is a very timely tool, allowing corrective actions to be directly taken in insufficiently covered areas.

[Poliomyelitis eradication in areas with armed conflict: the case of Afghanistan]. / La eliminación de la poliomielitis en zonas en conflicto: el caso de Afganistán.

The aim of this study was to describe fieldwork to erradicate poliomyelitis from Afghanistan and particularly from the Mazar Region. From 1997-1999, 365 cases of acute flaccid paralysis were detected. Of these, 216 cases (59.2%) were classified as poliomyelitis. The rate of acute flaccid paralysis improved from 0.1 in 1997 to 0.8 in 1999. Fieldwork in the Mazar region revealed under-notification and the need to improve surveillance methods. However, massive use of the services of traditional healers and extreme transport difficulties reduced the efficacy of the interventions. The case of Afghanistan suggests that epidemiological surveillance systems are feasible in countries with armed conflict, although such systems require considerable resources.

Implementation of a mass measles campaign in central Afghanistan, December 2001 to May 2002.

In Afghanistan health services have been disrupted by 23 years of conflict and 1 of 4 children die before age 5 years. Measles accounts for an estimated 35,000 deaths annually. Surveillance data show a high proportion of measles cases (38%) among those >/=5 years old. In areas with complex emergencies, measles vaccination is recommended for those aged 6 months to 12-15 years. From December 2001 to May 2002, Afghan authorities and national and international organizations targeted 1,748,829 children aged 6 months to 12 years in five provinces in central Afghanistan for measles vaccinations. Two provinces reported coverage of >90% and two >80%. Coverage in Kabul city was 62%. A subsequent cluster survey in the city found 91% coverage (95% confidence interval [CI], 0.85-0.91) among children 6-59 months and 88% (95% CI, 0.87-0.95) among those 5-12 years old. Thus, this campaign achieved acceptable coverage despite considerable obstacles.