Gaps persist in global yellow fever vaccination coverage, Aug 2017

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August 24, 2017

Notable gaps in vaccination persist in areas at risk of yellow fever virus transmission, with approximately 393.7 million to 472.9 million people still in need of immunization to reach 80% population coverage recommended by WHO, according to recent findings.

“In many yellow fever risk areas, vaccine coverage remains too low to prevent outbreaks,” Freya M. Shearer, DPhil candidate from the Big Data Institute at Li Ka Shing Center for Health Information and Discovery, and colleagues wrote inThe Lancet Infectious Diseases. “The course of the Angolan outbreak and international response reiterates the need for a sustained policy of preventive vaccination of at-risk populations to reduce the risk of epidemics.”

Researchers examined global yellow fever vaccination coverage from 1970 through 2016 to calculate how many individuals still require vaccination to reach the population coverage thresholds for outbreak prevention recommended by WHO. They performed an adjusted retrospective analysis using data compiled from WHO reports and health-service-provider registries that included yellow fever vaccination information between May 1, 1939, to Oct. 29, 2016. Shearer and colleagues calculated three population coverage values representing alternative scenarios to account for any uncertainty in how vaccine campaigns were targeted. They then combined that information with demographic data and tracked vaccination coverage through time across countries at risk of yellow fever transmission.

Their analysis revealed significant increases in yellow fever vaccine coverage since 1970. However, prominent gaps still exist in coverage within risk zones in Africa and Latin America. An assessment of yellow fever vaccination coverage by age group in 2016 showed improvement of routine infant vaccination programs in protecting children at the country level, but also revealed gaps in adult populations for most countries. Many individuals (between 393.7 million and 472.9 million) require vaccination in areas at risk of yellow fever virus transmission to reach WHO’s recommended 80% population coverage threshold, the researchers said. This represents between 43% and 52% of the population within the areas at risk, compared with between 66% and 76% of the population who would have needed immunization in 1970.

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“The results of this study highlight both important progress and gaps in yellow fever vaccination coverage within risk zones and provide credible estimates of the doses required for supplementary campaigns,” Shearer and colleagues wrote. “The risk of a yellow fever epidemic can be eliminated if effective vector control, vaccination and disease surveillance are enforced and maintained.”

Annelies Wilder-Smith

In a related commentary, Annelies Wilder-Smith, MD, PhD, MIH, professor of infectious diseases at Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, and president of the International Society of Travel Medicine, wrote that this study provides policymakers with the data crucially needed to control yellow fever.

“Absent or erratic control of proof of yellow fever vaccination at entry, falsified vaccine certificates, flawed risk assessments in travel medicine clinics, changing travel patterns and attitudes of travelers and inadequate information by travel medicine providers have led to preventable cases of yellow fever in travelers, which contributes to the spread into new areas,” she wrote. “Although the pre-emptive protection of endemic populations should be the main thrust, efforts should also be enhanced to contain outbreaks rapidly and to stop international spread. The onus is on the world to avoid vaccine shortfalls in the future.” – by Savannah Demko

Disclosures : Shearer reports no relevant financial disclosures. Please see the study for all other authors’ relevant disclosures. Wilder-Smith reports no relevant financial disclosures.

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Extreme Shortage of Yellow Fever Vaccine YF Vax in USA, Aug 2017 - CDC

15/08/2017
Announcement: Temporary Total Depletion of US Licensed Yellow Fever Vaccine Addressed by Availability of Stamaril Vaccine at Selected Clinics

Sanofi Pasteur, the manufacturer of the only yellow fever vaccine (YF-Vax) licensed in the United States, has announced that YF-Vax for civilian use is now totally unavailable from the manufacturer until mid-2018 because of delays in the production process. However, YF-VAX might be available at some clinics for several months, until remaining supplies at those sites are used up. Sanofi Pasteur applied and received approval from the US Food and Drug Administration (FDA) to make another yellow fever vaccine available in the United States under an investigational new drug (IND) program.*Manufactured by Sanofi Pasteur in France, this vaccine, Stamaril, is registered and distributed in more than 70 countries. It is comparable in safety and efficacy to YF-Vax.

In order to meet the requirements of the IND program, Sanofi Pasteur can provide Stamaril to only a limited number of clinics. Sanofi has identified sites throughout the United States to include in the program so patients can have continued access to yellow fever vaccine.

Travelers and health care providers can find locations that can administer Stamaril, and those clinics with remaining doses of YF-VAX, by visiting theyellow fever vaccination clinic search page. For information about which countries require yellow fever vaccination for entry and which countries the CDC recommends yellow fever vaccination, visit the CDC Travelers’ Health website (www.cdc.gov/travel).

For more information, contact Sanofi Pasteur at 1-800-VACCINE (1-800-822-2463).

*Although the name of the FDA program is "investigational new drug," Stamaril is not investigational or experimental. Stamaril has been used in European and other countries for decades but is not licensed in the United States. IND is the mechanism through which FDA gives approval for Stamaril to be imported.

More Information

• Yellow Fever
• http://www.sanofipasteur.us/vaccines/yellowfevervaccine

How to avoid yellow fever, August 2017

Dr Zubair Khaled Huq

Yellow fever is a viral disease of typically short duration. The disease is caused by the yellow fever virus and is spread by the bite of an infected female mosquito. It infects humans, other primates and several species of mosquitoes. In cities, it is spread primarily by Aedes aegypti, a type of mosquito found throughout the tropics and subtropics. Aedes aegypti also transmits the viruses that cause dengue fever, West Nile fever, chikungunya, eastern equine encephalitis and Zika virus.

In areas where yellow fever is common and vaccination is uncommon, early diagnosis of cases and immunisation of large parts of the population is important to prevent outbreaks. Death occurs in up to half of those who get severe disease.

Avoid mosquito bites    

When you go outdoors, use oil of lemon eucalyptus on exposed skin. Wear proper clothing to avoid mosquito bites. When weather permits, wear long-sleeves, long pants and socks when outdoors. Mosquitoes may bite through thin clothing, so spraying clothes with repellent containing Permethrin gives extra protection. Mosquito repellents containing Permethrin are not approved for application directly to skin. Be aware of peak mosquito hours. The peak biting time for many mosquito species is dusk to dawn. However, Aedes aegypti feeds during the daytime.

Get vaccinated if recommended              

Yellow fever vaccine is recommended for persons aged ≥ 9 months who are travelling to or living in areas at risk for yellow fever virus transmission in South America and Africa. Mosquitoes acquire the virus by feeding on infected primates (monkeys), and then can transmit the virus to other primates (human or non-human). People infected with yellow fever virus are infectious to mosquitoes (referred to as being ‘viraemic’) shortly before the onset of fever and up to 5 days after onset.

Symptoms

The majority of persons infected with yellow fever virus have no illness or only mild illness. In persons who develop symptoms, the incubation period is typically 3–6 days. The initial symptoms include sudden onset of fever, chills, severe headache, back pain, general body ache, nausea, vomiting, fatigue and weakness. Most persons improve after the initial presentation. Roughly 15% of cases progress to develop a more severe form of the disease. The severe form is characterised by high fever, jaundice, bleeding and eventually shock and failure of multiple organs.

Treatment

No specific treatments have been found to benefit patients with yellow fever. Whenever possible, yellow fever patients should be hospitalised for supportive care and close observation. Treatment is symptomatic. Rest, fluids, and use of pain relievers and medication to reduce fever may relieve symptoms of aching and fever. Yellow fever patients should be protected from further mosquito exposure (staying indoors and/or under a mosquito net) for up to 5 days after the onset of fever.

Outcome

The majority of infected persons will be asymptomatic or have mild disease with complete recovery. In persons who become symptomatic but recover, weakness and fatigue may last several months. Those who recover from yellow fever generally have lasting immunity against subsequent infection.

The writer is a physician, public health specialist & a gerontologist.

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New Yellow Fever Virus Recombinant Protein for Diagnostic Testing Launched, August 2017

Aalto Bio Reagents have announced the availability of its first-to-market recombinant Yellow Fever virus (YFV) protein (code CA 6325) for diagnostic test manufacturers, vaccine developers and researchers globally. This His-tagged, recombinant protein is expressed in HEK293 cells and is derived from strain 17D. YFV, a potentially fatal mosquito-borne flavivirus, is prevalent in tropical and subtropical locations in South America and Africa.

YFV is transmitted to humans mainly by sylvatic mosquito vectors of the genera Haemagogus and Sabethes, but has also been known to be spread by the sinister Aedes aegypti mosquito which is responsible for the current Zika virus epidemic. In humans, the majority of YFV infections are asymptomatic; however approximately 15% of infected patients enter what is known as the toxic phase and this can lead to severe complications such as jaundice, multi-organ failure and even death.

Laboratory diagnosis is generally accomplished by means of serological testing for the detection of antibodies during the postviremic phase of the disease (i.e. from the 5th day since the onset of symptoms). YFV is difficult to diagnose, especially in the early stages, as cross-reaction with other flavivirus infections is common. There are no validated IgM ELISA kits commercially available at present and in order for YFV infection to be confirmed by serologically techniques, a differential diagnosis with other flavivirus infections must be carried out.

Philip Noone, CEO of Aalto Bio Reagents, said “Brazil is currently experiencing its largest YFV outbreak in decades. There is an urgent need for a specific and sensitive serological YFV assay in countries such as Brazil, where co-circulation with other flaviviruses is high. Our industry has an unrelenting requirement for access to the most scientifically proven raw materials, a broader range of flexible controls and faster diagnostics. With our Zika, Chikungunya, Dengue Triplex and now our Yellow Fever solution we are truly building a comprehensive tropical product listing to meet this need. We envisage that our YFV protein will provide the critical element to further diagnostic companies’ research and development of IgG and potentially IgM assays. We will continue to focus on the expansion of our tropical disease products with even more additions in 2017-18 to enable our customers to bring superior, best-in-class diagnostic products to market faster, and aid in the development of life-saving vaccines.”

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