Clustered lot quality assurance sampling: a tool to monitor immunization coverage rapidly during a national yellow fever and polio vaccination campaign in Cameroon, May 2009
Pezzoli, L.; Tchio, R.; Dzossa, A.D.; Ndjomo, S.; Takeu, A.; Anya, B.; Ticha, J.; Ronveaux, O.; Lewis, R.F.
Epidemiology and Infection 140(1): 14-26
2012
ISSN/ISBN: 0950-2688 PMID: 21418714 DOI: 10.1017/s0950268811000331Document Number: 535019
We used the clustered lot quality assurance sampling (clustered-LQAS) technique to identify districts with low immunization coverage and guide mop-up actions during the last 4 days of a combined oral polio vaccine (OPV) and yellow fever (YF) vaccination campaign conducted in Cameroon in May 2009. We monitored 17 pre-selected districts at risk for low coverage. We designed LQAS plans to reject districts with YF vaccination coverage <90% and with OPV coverage <95%. In each lot the sample size was 50 (five clusters of 10) with decision values of 3 for assessing OPV and 7 for YF coverage. We 'rejected' 10 districts for low YF coverage and 14 for low OPV coverage. Hence we recommended a 2-day extension of the campaign. Clustered-LQAS proved to be useful in guiding the campaign vaccination strategy before the completion of the operations.