Yellow fever control: current epidemiology and vaccination strategies

Abstract

Yellow fever (YF) outbreaks continue, have expanded into new areas and threaten large populations in South America and Africa. Predicting where epidemics might occur must take into account local mosquito populations and specific YF virus strain, as well as ecoclimatic conditions, sociopolitical and demographic factors including population size, density, and mobility, and vaccine coverage. Populations of Aedes aegypti and Aedes albopictus from different regions vary in susceptibility to and capacity to transmit YF virus. YF virus cannot be eliminated today because the virus circulates in animal reservoirs, but human disease could be eliminated with wide use of the vaccine. WHO EYE (Eliminate Yellow Fever Epidemics) is a welcome plan to control YF, with strategies to be carried out from 2017 to 2026: to expand use of YF vaccine, to prevent international spread, and to contain outbreaks rapidly. YF vaccination is the mainstay in controlling YF outbreaks, but global supply is insufficient. Therefore, dose-sparing strategies have been proposed including fractional dosing and intradermal administration. Fractional dosing has been effectively used in outbreak control but currently does not satisfy International Health Regulations; special documentation is needed for international travel. Vector control is another facet in preventing YF outbreaks, and novel methods are being considered and proposed.

Innate Immune DNA Sensing of Flaviviruses

“…YFV is also transmitted by Aedes aegypti mosquitoes and was first isolated from the blood of a patient in Ghana in 1927, and an effective vaccine (17D strain) was subsequently made available in 1937 [7]. Despite this, YFV infections have remained a threat to global health, with outbreaks expanding into new areas that put large populations in South America and Africa at risk [1,132]. YFV is currently endemic in over 45 countries globally and causing around 200,000 severe cases and up to 60,000 deaths every year according to a WHO estimation [132].…”

Activation of an Effective Immune Response after Yellow Fever Vaccination Is Associated with the Genetic Background and Early Response of IFN-γ and CLEC5A

“…Yellow fever (YF) is a potentially fatal mosquito-borne disease caused by the neurovirulent and viscerotropic YF virus (YFV), from the genus flavivirus, family Flaviviridae . The mainstay of YF control involves control of the mosquito vectors Aedes Albopictus and Aedes aegypti , and vaccination [ 1 ]. The attenuated YF vaccine was developed in 1937 by Theiler and Smith through serial passages of the YFV wild-type Asibi strain in mice and chick minced embryo culture, generating the non-neurovirulent strain 17D which protected monkeys from challenge with a virulent strain of the virus with production of neutralizing antibodies [ 2 ].…”

A Yellow Fever Virus 17D Infection and Disease Mouse Model Used to Evaluate a Chimeric Binjari-Yellow Fever Virus Vaccine

“…Large outbreaks have occurred in recent years in Angola, Democratic Republic of Congo and Brazil [ 2 ]. A revised strategy to Eliminate Yellow Fever Epidemics (EYE) was launched by the World Health Organization (WHO) in 2017, with affordable vaccines and a sustained vaccine market representing key objectives [ 3 , 4 ]. Yellow fever (YF) is prevented by an effective live attenuated vaccine (17D), with a single dose able to confer life-long protection in most people.…”