2 Citations 529 Views 125 Downloads
Background: Substantial outbreaks of yellow fever in Angola and Brazil in
the past 2 years, combined with global shortages in vaccine stockpiles,
highlight a pressing need to assess present control strategies. The aims
of this study were to estimate global yellow fever vaccination coverage
from 1970 through to 2016 at high spatial resolution and to calculate the
number of individuals still requiring vaccination to reach population
coverage thresholds for outbreak prevention. Methods: For this adjusted
retrospective analysis, we compiled data from a range of sources (eg, WHO
reports and health-service-provider registeries) reporting on yellow fever
vaccination activities between May 1, 1939, and Oct 29, 2016. To account
for uncertainty in how vaccine campaigns were targeted, we calculated
three population coverage values to encompass alternative scenarios. We
combined these data with demographic information and tracked vaccination
coverage through time to estimate the proportion of the population who had
ever received a yellow fever vaccine for each second level administrative
division across countries at risk of yellow fever virus transmission from
1970 to 2016. Findings: Overall, substantial increases in vaccine coverage
have occurred since 1970, but notable gaps still exist in contemporary
coverage within yellow fever risk zones. We estimate that between 393·7
million and 472·9 million people still require vaccination in areas at
risk of yellow fever virus transmission to achieve the 80% population
coverage threshold recommended by WHO; this represents between 43% and 52%
of the population within yellow fever risk zones, compared with between
66% and 76% of the population who would have required vaccination in 1970.
Interpretation: Our results highlight important gaps in yellow fever
vaccination coverage, can contribute to improved quantification of
outbreak risk, and help to guide planning of future vaccination efforts
and emergency stockpiling.
529 views reported since publication in 2018.