Oral cholera vaccine coverage in hard-to-reach fishermen communities after two mass Campaigns, Malawi, 2016.

ABSTRACT

CONTEXT From December 2015 to August 2016, a large epidemic of cholera affected the fishermen of Lake Chilwa in Malawi. A first reactive Oral Cholera Vaccines (OCV) campaign was organized, in February, in a 2km radius of the lake followed by a preemptive one, conducted in November, in a 25km radius. We present the vaccine coverage reached in hard-to-reach population using simplified delivery strategies. METHOD: We conducted two-stage random-sampling cross-sectional surveys among individuals living in a 2km and 25km radius of Lake Chilwa (islands and floating homes included). Individuals aged 12months and older from Machinga and Zomba districts were sampled 43 clusters of 14 households were surveyed. Simplified strategies were used for those living in islands and floating homes self- delivery and community-supervised delivery of the second dose. Vaccine coverage (VC) for at-least-two-doses was estimated taking into account sampling weights and design effects. RESULTS: A total of 1176 households were surveyed (2.7% of non-response). Among the 2833 individuals living in the 2km radius of Lake and the 2915 in the 25km radius 457 (16.1%) and 239 (8.2%) lived in floating homes or on islands at some point in the year, respectively. For the overall population, VC was 75.6% and 54.2%, respectively. In the 2km radius, VC was 92.2% for those living on the lake at some point of the year 271 (64.8%) used the simplified strategies. The main reasons for non-vaccination were absence during the campaign and vaccine shortage. Few adverse events occurring in the 24h following vaccination was reported. CONCLUSIONS: We reached a high two-dose coverage of the most at-risk population using simplified delivery strategies. Because of the high fishermen mobility, regular catch-up campaigns or another strategy specifically targeting fishermen need to be assessed for more efficient vaccines use.