The National (level 1), State (L2), and Local government vaccine cold stores (L3) as well as some vaccination centres (L4) were physically inspected in Lagos State, Nigeria and the potency of the live-attenuated measles vaccine was tested. Both the L1 and L2 storage facilities were formally adequately equipped and maintained. This was also reflected in the potency of the vaccines. However, many vaccines at L1 were within weeks from expiration. Considerable problems with refrigeration and delayed forwarding became apparent at level L3 causing loss in potency both at L3 and L4: although, all L4 stores check-listed met all the EPI/NPI accreditation criteria, ¾ of the vaccines were sub-potent and this situation did not improve over the three year study period (1996-98). Time to expiration did not seem to be the main cause of loss of potency but rather poor and delayed handling. It is recommended that vaccines are moved more rapidly through the system and used well before expiration. Because of frequent power failures despite standby generators, we further recommend to include in the WHO criteria, book-keeping of periods of power failures, running time of generators and a complete recording of fuel consumption. Attitudes among vaccinating staff and handling of vaccines should also be improved by continued training.
Keywords: Measles vaccine; cold stores; potency
African Journal of Clinical and Experimental Microbiology Vol. 8 (1) 2007: pp. 1-7
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