Yellow Fever Vaccines

Yellow Fever Vaccines

Safe and effective yellow fever vaccines have been available for more than 80 years, says the U.S. CDC. The yellow fever vaccine is a live, weakened form of the virus. It is given as a single subcutaneous (or intramuscular) injection.

Yellow Fever vaccination is recommended for people aged 9 months or older and who are traveling to or living in areas at risk for the yellow fever virus, such as in Africa and South America. The CDC suggests speaking with a healthcare provider to determine if you need a yellow fever vaccination or a booster shot before your trip to an area at risk for yellow fever.

On August 1, 2019, a study published by the NEJM concluded: 'A fractional dose of the 17DD yellow fever vaccine was effective at inducing seroconversion in participants who were seronegative at baseline. Titers remained above the threshold for seropositivity at 1-year after vaccination in nearly all participants who were seropositive at 1-month after vaccination. These findings support the use of fractional-dose vaccination for outbreak control.'

Yellow Fever Vaccines

YF-VAX Vaccine: YF-VAX is prepared by culturing the 17D-204 strain of yellow fever virus in living avian leukosis virus-free chicken embryos. The vaccine contains sorbitol and gelatin as a stabilizer, is lyophilized, and is hermetically sealed under nitrogen. No preservative is added. YF-Vax is licensed in the USA and expects to become available in late 2020.

Stamaril Vaccine: Stamaril is a live, attenuated yellow fever vaccine that contains the active substance Yellow fever virus 17D-204 strain produced in specified pathogen-free chick embryos. Stamaril has been offered in Europe and other countries for decades. Stamaril yellow fever vaccine is currently distributed in over 70 countries and is available in the USA during 2020. However, it is considered investigational in the USA, as it is not a U.S.-licensed product.

Yellow Fever Vaccine News

November 2, 2020 - The Nigeria Centre for Disease Control (NCDC) reported to the WHO a cluster of deaths in Ute Okpu community in Ika North-East local government area (LGA) of Delta State. Additional cases were reported from 4 other wards of Ika North-East (Idumessah, Owa Alero, Owanta, and Umunede). A preliminary report for Delta State on November 5, 2020, notified of 48 suspected cases of yellow fever (YF) with 30 deaths (CFR 62.5%). The YF vaccination status of most of the suspected cases is unknown.

October 26, 2020 - Despite the COVID-19 pandemic, the South Sudan Ministry of Health with support from Eliminate Yellow Fever Epidemics partners including Gavi, the Vaccine Alliance, WHO, UNICEF, and other launched a reactive yellow fever vaccination campaign in Kajo, Keji, Central Equatoria State. The campaign aims to protect over 90,000 individuals aged 9 months to 60 years from yellow fever infection.

October 24, 2020 - Case Report: Invasive aspergillosis complication in yellow fever vaccine-induced viscerotropic disease.

August 23, 2020 - The WHO announced the Africa country of Senegal confirmed a yellow fever case. A larval survey of water sources near the patient's home found mosquito infestation rates and a high proportion were Aedes aegypti, a known carrier of the yellow fever virus.

August 1, 2020 - The WHO stated Yellow fever is endemic in French Guiana. This new case report illustrates the importance of maintaining awareness of the need for yellow fever vaccination, especially in areas with a favorable ecosystem for yellow fever transmission. The WHO recommends vaccination against yellow fever at least 10 days prior to the travel for all international travelers to French Guiana, from nine months of age. French Guiana also requires a yellow fever vaccination certificate for travelers over one year of age.

July 28, 2020 - Changing temperature and rainfall across Africa could increase yellow fever deaths by up to 25 percent by 2050. This is according to new modeling of the burden of yellow fever by scientists at Imperial College London and the WHO. It suggests that some East African countries including Ethiopia and Somalia may be increasingly impacted by yellow fever in the coming decades and that future vaccine programs will need to counteract this.

June 25, 2020 - Sanofi Pasteur, the manufacturer of the only yellow fever vaccine (YF-Vax) licensed in the United States, has announced a total depletion of YF-Vax as they transition to a new production facility. They are reassessing the timing of YF-Vax return to supply and expect to provide an update in December 2020.

April 2020 - Sanofi Pasteur’s new U.S. YF-VAX® (Yellow Fever Vaccine) production facility has been licensed by the U.S. Food and Drug Administration (FDA) and doses continue to progress through manufacturing. We expect to have more information on the return of YF-VAX in December 2020. The Expanded Access Investigational New Drug Application Program (EAP) is expected to continue through 2020. In the U.S., Sanofi Pasteur has worked with the FDA to provide access to another yellow fever vaccine through this EAP. Manufactured by Sanofi Pasteur in France, this vaccine, STAMARIL® (Yellow Fever Vaccine [Live]), is registered and distributed in more than 70 countries.

September 30, 2019 - Oregon Health & Science University spinoff Najít Technologies, Inc., of Beaverton, Oregon, will test a yellow fever version of the HydroVax vaccine platform licensed from OHSU. A $3.1-million grant from the National Institutes of Health to Najít will enable Duke University to lead the Phase 1 human clinical trial, and OHSU to study how trial participants’ immune systems respond to the yellow fever vaccine. The trial is expected to take up to a year to complete.

July 19, 2019 - A Randomized Phase I Clinical Trial of HydroVax-YFV, a Novel Inactivated Yellow Fever Vaccine.

July 26, 2019 - Characterization of recombinant yellow fever-dengue vaccine viruses with human monoclonal antibodies targeting key conformational epitopes.

Yellow Fever Vaccine Indication

For most people, a single dose of yellow fever vaccine provides protection, and a booster dose of the vaccine is not needed. However, travelers going to areas with ongoing virus outbreaks may consider getting a booster dose of yellow fever vaccine if it has been 10 years or more since they were last vaccinated. Certain countries might also require a booster dose of the vaccine prior to granting entry.

Some people may have an increased risk of developing a reaction to the vaccine, but may still benefit from being vaccinated, says the CDC. Contraindications include severe hypersensitivity to egg antigens and severe immunodeficiency. 

Yellow fever vaccines provide effective immunity in about 10 days for 80-100% of people vaccinated, and within 30 days for more than 99% of people vaccinated, says the WHO.

Yellow Fever Virus Epidemics

Large epidemics of yellow fever occur when infected people introduce the virus into heavily populated areas with high mosquito density and where most people have little or no immunity, due to lack of vaccination. In these conditions, infected mosquitoes of the Aedes aegypti species transmit the virus from person to person.

Forty-seven countries in Africa (34) and Central and South America (13) are either endemic for, or have regions that are endemic for, yellow fever, said the WHO, as of May 2019.

The U.S. CDC publishes a list of epidemic countries on this webpage. And the WHO publishes its list on this webpage.

Yellow Fever Virus Overview

Yellow fever is an acute viral hemorrhagic disease transmitted by infected mosquitoes. The "yellow" in the name refers to jaundice that affects some patients, says the WHO.

Symptoms of yellow fever include fever, headache, jaundice, muscle pain, nausea, vomiting, and fatigue. A small proportion of patients who contract the virus develop severe symptoms and approximately half of those die within 7 to 10 days.

Yellow Fever Diagnosis

Yellow fever is difficult to diagnose, especially during the early stages. A more severe case can be confused with severe malaria, leptospirosis, viral hepatitis, other hemorrhagic fevers, infection with other flaviviruses, and poisoning says the WHO.

Polymerase chain reaction testing in blood and urine can sometimes detect the virus in the early stages of the disease. In later stages, testing to identify antibodies is needed.

Yellow Fever FAQs

The U.S. CDC publishes a list of frequently asked questions and answers, which can be found at this CDC webpage.

And the WHO's FAQ list is found on this webpage.

Note: The content on this webpage has been aggregated from the WHO, the U.S. CDC, research studies, and has been reviewed by healthcare providers, such as Dr. Robert Carlson.