Intervene before leaving: clustered lot quality assurance sampling to monitor vaccination coverage at health district level before the end of a yellow fever and measles vaccination campaign in Sierra Leone in 2009

Pezzoli L, Conteh I, Kamara W, Gacic-Dobo M, Ronveaux O, Perea WA, Lewis RF. Intervene before leaving: clustered lot quality assurance sampling to monitor vaccination coverage at health district level before the end of a yellow fever and measles vaccination campaign in Sierra Leone in 2009. BMC Public Health. 2012; 12: 415.