Yellow Fever Vaccines 2022

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Last reviewed
May 22, 2022

Yellow Fever Vaccines For 2022

Safe and effective yellow fever vaccines have been available for more than 80 years. Yellow Fever vaccination is recommended for people aged nine months or older and traveling to or living in areas at risk for the yellow fever virus, such as in regions of Africa and South America

And the U.S. CDC suggests speaking with a healthcare provider to determine if you need a yellow fever vaccination or a booster shot before traveling to an area at risk for yellow fever.

As of May 22, 2022, the YF-VAX vaccine was available in the U.S. at travel vaccine-certified pharmacies, and the Stamaril vaccine remains available internationally.

Yellow Fever Vaccines - Approved For 2022

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, lyophilized, and hermetically sealed under nitrogen. No preservative is added. YF-Vax is licensed in the USA and is available in 2021. STN:  BL 103915

Stamaril Vaccine: Stamaril is a live, attenuated yellow fever vaccine containing the active 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. However, it is considered investigational in the U.S.

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

Yellow Fever Vaccine Candidate in 2022

RegaVax is a vector vaccine candidate that uses the yellow fever vaccine virus's genetic code as a carrier (or vector) for the coronavirus spikes' genetic code. RegaVax is a platform technology to design and produce live-attenuated recombinant vaccines vectored by the original yellow fever vaccine (YF17D).

Najít Technologies HydroVax-002 YFV is a Novel Inactivated Yellow Fever vaccine candidate conducting phase 1 clinical research with the NIH, evaluating dosages of 1 mcg and 5 mcg given intramuscularly on Day 1 and Day 29.

Yellow Fever Monoclonal Antibody Treatment

The TY014 treatment candidate is directed against the envelope protein on the surface of the Yellow Fever virus and prevents viral replication by limiting viral fusion to host cells. Tysana Pte Ltd is currently conducting a phase 1 study on humans.

Yellow Fever Vaccination Requirements For 2022

In the U.S., it's easy to search for a Yellow Fever Vaccination Clinic at this CDC webpage. In addition, you should receive a yellow card called the International Certificate of Vaccination to prove that you have had a yellow fever vaccine. The U.K. government published a standardized pre-vaccination checklist for 2022 to ensure the yellow fever vaccine is indicated for the destination and to identify vaccine contraindications.

As of May 2022, an interactive world map showing travel recommendations by destination and yellow fever vaccination requirements for specific countries is available on the CDC Travelers' Health webpage. Forty-seven countries in Africa (34) and Central and South America (13) are either endemic or have yellow fever endemic regions, reported the WHO on March 25, 2022.

The U.S. CDC recently issued yellow fever Travel Advisories for Ghana and Nigeria and suggested pre-trip vaccinations before visiting Brazil. In addition, since September 2021, nine countries in the WHO African Region (Cameroon, Chad, Central African Republic, Côte d'Ivoire, the Democratic Republic of Congo, Ghana, Niger, Nigeria, and the Republic of Congo) have reported human laboratory-confirmed cases of yellow fever. And proof of yellow fever vaccination is required to visit areas in Argentina, AngolaBoliviaBrazil, the CaribbeanCosta Rica, GhanaJamaica, Kenya, Paraguay, Rwanda, and Uganda.

Yellow Fever Outbreak and Vaccine News For 2021 - 2022

May 4, 2022 - The U.S. CDC issued an Alert - Level 2, Practice Enhanced Precautions, regarding a yellow fever outbreak in Nigeria. Furthermore, the December 2021 Alert for Yellow Fever in Ghana continues to be in effect.

April 25, 2022 - The WHO reported seven suspected cases in Uganda that tested positive for yellow fever antibodies by plaque reduction neutralization test. 

April 13, 2022 - Tocantins State Health Department reported a recent yellow fever death, an unvaccinated tourist in the south of the Brazilian state. Since 2018, Tocantins has not recorded cases of Yellow Fever in humans.

April 7, 2022 - Emergex Vaccines Holding Limited announced an agreement with ATCC to progress the preclinical development of its T-Cell Yellow Fever booster vaccine candidate.

March 25, 2022 - The WHO reported 53 suspected yellow fever cases, including six deaths in the Republic of Kenya in early 2022. Kenya's last reported yellow fever outbreak was in 2011. Furthermore, the WHO-UNICEF estimated coverage through routine yellow fever immunization is 7% of the target population in the central area of Kenya. The WHO assesses the public health risk as high at Kenya's national and regional levels.

March 18, 2022 - Rwanda's Ministry of Health announced all residents and visitors traveling to yellow fever endemic countries should be vaccinated at least ten days before traveling.

March 14, 2022 - The U.K. reported Kenya's Ministry of Health confirmed a yellow fever outbreak in Isiolo County. The first case was detected on 12 January 2022, and as of 5 March 2022, a total of 15 cases, with three deaths, are reported.

March 13, 2022 - The WHO Africa reported eight villages in three Kenya sub-counties had been affected. The detection of yellow fever cases is concerning as Kenya has negligible population immunity in the districts reporting confirmed cases. In addition, the overall national immunity is thus far below the threshold necessary to provide herd immunity.

March 8, 2022 - BMC Public Health published new research: Changing epidemiology of yellow fever virus in Oyo State, Nigeria. While the Eliminating Yellow fever Epidemic strategy launched in Nigeria in April 2018, substandard vaccination coverage continues to be a cause for concern.

February 11, 2022 - Paraguay's authorities confirmed proof that yellow fever vaccination is required for travelers arriving from or leaving for Bolivia, Brazil, Peru, and Venezuela.

January 22, 2022 - The Costa Rica Ministry of Health confirmed the Yellow Fever vaccine will not be available until late February 2022.

December 13, 2021 - The U.S. CDC issued a Level 2 Travel Advisory for Ghana's ongoing yellow fever outbreak.

December 1, 2021 - The WHO reported from 15 October to 27 November 2021, there were 202 suspected cases of Yellow Fever, including 70 confirmed cases and 35 deaths [Case Fatality Ratio: 17%] reported in four regions in Ghana (Savannah, Upper West, Bono and Oti regions) in Africa.

November 16, 2021 - The U.K. published a pre-vaccination checklist to ensure the yellow fever vaccine is indicated for the intended travel destination and enable vaccinators to identify existing contraindications or precautions.

November 8, 2021 - Change in vaccination strategy averted outbreak of urban yellow fever in São Paulo, Brazil, scientists say.

November 8, 2021 - The WHO Africa reported technical officers in the National Public Health Laboratory had increased testing capacity in South Sudan to control yellow fever outbreaks.

November 5, 2021 - Local media reported residents of Belo Horizonte who plan to visit the parks in the capital of Minas Gerais, located in southwest Brazil, are required a yellow fever vaccination. The rule began to be applied in 15 other places.

September 30, 2021 - The U.S. CDC issued a Level 2 Travel Advisory for Nigeria regarding its yellow fever outbreak. All travelers nine months or older going to Nigeria should receive vaccination against yellow fever at least ten days before travel.

October 29, 2021 - Ghana Health received a notice from the Savannah Region that a disease has led to the deaths of eight people.

October 28, 2021 - Sanofi Chief Executive Officer, Paul Hudson, commented: "Sanofi has delivered outstanding financial results in the third quarter. Travel and other endemic vaccines sales increased 16.9% versus a low 2020 basis.

October 22, 2021 - The Smithsonian published an article: In 19th-Century Gibraltar, Survivors of a Deadly Virus Used 'Fever Passes' to Prove Their Immunity.

October 13, 2021 - The WHO confirmed the IHR National Focal Point for Venezuela reported seven confirmed human cases of yellow fever, which were investigated between 23 and 24 September 2021. The reverse transcriptase-polymerase chain reaction confirmed all seven patients at the Rafael Rangel National Hygiene Institute. Six of the seven reported cases were not vaccinated.

October 1, 2021 - The WHO reported since September 2017, yellow fever cases have been reported across several states in Nigeria. From January to 31 August 2021, a total of 1,312 suspected cases were reported in 367 Local Government Areas (LGAs) across 36 States and the Federal Capital Territory. A total of 45 blood samples were sent to the Institut Pasteur in Dakar, and 31 samples tested positive by Plaque reduction neutralization test (PRNT). Of these 31 PRNT positive cases, twelve had a yellow fever vaccination history. Two deaths were reported among the remaining 19 non-vaccinated PRNT positive cases (Case fatality ratio: 11%). 

September 30, 2021 - The U.S. CDC issued an Alert - Level 2, Practice Enhanced Precautions, regarding Nigeria's yellow fever outbreak.

September 30, 2021 - The Nigeria Centre for Disease Control reported yellow fever outbreaks in multiple states (Bauchi, Benue, Delta, Ebonyi, and Enugu), as confirmed by the Nigerian National Reference Laboratory. The government of Nigeria requires that all travelers nine months of age or older show proof of yellow fever vaccination to enter the country.

September 12, 2021 - People in Taiwan can get inoculated against yellow fever for free through November 2021. The Centers for Disease Control confirmed that health authorities want to use more than 9,000 doses of the vaccine before they expire. The vaccine, which normally costs NT$2,152.

September 5, 2021 - The WHO Africa Region reported from January to 9 August 2021, a total of nine presumptive cases of yellow fever in Cameron, including three deaths (case fatality rate 33 %), tested positive by plaque reduction neutralization test (PRNT) at the Centre Pasteur in Cameroun (CPC). These cases originated from six different regions with a total of nine health districts (H.D.s) affected: Adamaoua region (Ngaoundere rural H.D.), Far North region (Maga, Mogode, Yagoua HD), Littoral region (Yabassi HD), North region (Guider, Garoua 1 H.D.s), North-West region (Bamenda H.D.), and Centre region (Eséka HD).

August 10, 2021 - The WHO Africa posted a video on YouTube - Documentary: Yellow fever preventive mass vaccination campaign, Democratic Republic of Congo, 2021.

June 30, 2021 - The U.S. CDC issued a Level 2 Travel Alert regarding an outbreak of yellow fever in Nigeria. The episode is currently in Bauchi, Benue, Delta, Ebonyi, and Enugu states. Unless vaccinated, travelers should not visit these areas. In addition, travelers to Nigeria should take steps to prevent yellow fever by getting vaccinated at least ten days before travel and taking steps to avoid mosquito bites.

June 16, 2021 - The Ministry of Health, with support from Eliminate Yellow Fever Epidemics (EYE) partners, including WHO, GAVI, the Vaccine Alliance, UNICEF, and other health implementing partners, have completed a pre-emptive yellow fever vaccination campaign. The campaign targeting 57,443 individuals aged nine months to 60 years was conducted in Morobo, Lainya, and Yei River Counties in Central Equatoria State neighboring Kajo-Keji, where Yellow Fever was confirmed in 2020. At the end of the campaign, 56,640 (98.6%) of individuals aged nine months to 60 years received the yellow fever vaccine in Morobo, Lainya, and Yei River counties. In March 2020, two laboratory-confirmed yellow fever cases were reported in Kajo-keji County following a comprehensive cross-border outbreak investigation after a yellow fever outbreak was declared in the neighboring Moyo district of Uganda.

April 14, 2021 - A new study published by Cell conducted by an international team of researchers, including the London School of Hygiene & Tropical Medicine and the Liverpool School of Tropical Medicine, found high-density natural Wolbachia infections in Anopheles mosquito populations. They also showed that two strains of this bacteria are maternally transmitted to following generations and have genes associated with rapidly invading mosquito populations. This study is the first to show that Wolbachia strains naturally occur at high prevalence in wild Anopheles moucheti and Anopheles demeilloni mosquito populations, the vectors of the malaria parasite.

April 6, 2021 - Gavi wrote The Next Pandemic: Yellow Fever. 'So far, yellow fever has never been reported in Asia or the Western Pacific, but, as Aedes aegypti is endemic in these regions, it would only take a few introductions by people traveling from Africa or South America for the virus to spread rapidly. As Asia has never had yellow fever, this could be disastrous as there would be no natural immunity. There could be hundreds of thousands of cases before adequate vaccination coverage could be achieved.'

April 5, 2021 - Sanofi Pasteur announced that YF-VAX is once again available for purchase in the United States. Providers with a current Yellow Fever Vaccination Stamp issued by their state or territorial health department may now order YF-VAX from the manufacturer.

March 31, 2021 - In the second and concluding part of a report, Ebuka Onyeji investigates why the scarcity of Yellow fever vaccines occurred in the areas where they were most needed in Nigeria.

March 19, 2021 - The Ugandan National Medical Stores is set to vaccinate 300 people against yellow fever in Arua city in the West Nile region between March 23 and 25, 2021. In 2020, the Ministry of Health launched the yellow fever vaccination campaign in West Nile after the disease claimed four lives. The vaccination campaign targets 1.6 million people in six districts following an outbreak of Yellow Fever in Buliisa and four communities in West Nile, which claimed four lives in the affected districts. The targeted high-risk districts include Koboko, Maracha, Moyo, Obongi, and Yumbe. Uganda is considered a high-risk country for yellow fever by the WHO.

March 9, 2021 - The Canadian Committee to Advise on Tropical Medicine and Travel (CATMAT) issued a statement confirming fractional dosing is no longer valid as the shortage of Yellow Fever vaccine has been lifted. CATMAT recommends that anyone who received a fractional dose of the Yellow Fever vaccine while the shortage was in effect should now get a regular dose of the vaccine if traveling to an area where yellow fever vaccination is recommended or required. Note: This statement might be put back into effect should any shortages occur again.

March 19, 2021 - The National Medical Stores (NMS) announced it would vaccinate 300 people between 9 months to 59 years against yellow fever in Arua city in the West Nile region between March 23 and 25, 2021. NMS's Principal Public Relations Officer, Dan Kimosho, said the corporation came up with giving free yellow fever vaccination to Ugandans as part of corporate social responsibility, realizing that yellow fever vaccination is at a high-cost health facility. Kimosho explained that in partnership with the Ministry of Health and Uganda Revenue Authority, more than 7,500 people were vaccinated during the three-day exercise, which started on 25th September and ended on 27th September 2019, at Kololo Ceremonial Grounds in Kampala as part of the National Tax Payers Appreciation Week. 

March 7, 2021 - In a recent paper, researchers were able to quantify preventive mass vaccination campaigns (PMVC) to reduce yellow fever outbreaks at the province level using the self-controlled case series method. PMVCs in Africa averted an estimated 22% to 45% of outbreaks during this study period.

March 1, 2021 - There is an outbreak of yellow fever in Nigeria, first reported in November 2020, said the U.S. CDC. The outbreak is currently in Bauchi, Benue, Delta, Ebonyi, and Enugu states. Unless vaccinated, travelers should not visit these areas. In addition, travelers to Nigeria should take steps to prevent yellow fever by getting vaccinated at least ten days before travel and taking steps to avoid mosquito bites.

February 18, 2021 - PLOS published a new study: Assessing the impact of preventive mass vaccination campaigns on yellow fever outbreaks in Africa: A population-level self-controlled case series study. This study provides new empirical evidence of the high preventive impact of PMVCs on yellow fever outbreaks. Furthermore, this study illustrates that the SCCS method can be advantageously applied at the population level to evaluate a public health intervention.

February 8, 2021 - The ECDC published the Yellow fever - Annual Epidemiological Report for 2019. For 2019, there were no reported cases of yellow fever in the EU/EEA. For the previous year, 2018, EU/EEA countries reported 13 travel-related yellow fever cases, the highest number. Vaccination is the most important preventive measure against yellow fever. As described in WHO documents, the vaccine is safe, affordable, highly effective, and a single dose is sufficient to confer sustained immunity and lifelong protection against yellow fever. In addition, the vaccine provides effective immunity within 30 days for 99% of those vaccinated.

January 22, 2021 - The Washington Post published: The argument against vaccine passports is growing. Government and tourism officials speak out against mandatory vaccinations for international travel — though for different reasons.

January 9, 2021 - The Lancet published: Immunogenicity and safety of fractional doses of yellow fever vaccines: a randomized, double-blind, non-inferiority trial.

January 8, 2021 - Giving people a fraction of a yellow fever vaccine is effective. It could help vaccinate millions of more people during emergencies, according to results of a recent study led by Médecins Sans Frontiéres' research arm Epicentre, published in The Lancet. These clinical trial results found that giving a person one-fifth of the standard yellow fever vaccine dose effectively and safely will make it easier for governments and international organizations to prevent people from getting sick from yellow fever during outbreaks in times of vaccine shortage.

December 29, 2020 - The WHO report even confirmed yellow fever cases from October to December 2ses had been reported from four health districts in three regions in Senegal. The outbreak consists of four confirmed cases from three health zones in Kidira health district, Tambacounda region; one case in the neighboring Kedougou health district, Kedougou region; one case in Saraya district, Kedougou region; and one case in Thilogne health district, Matam region.

December 23, 2020 - Sanofi announced, 'To help meet U.S. needs, the continued yellow fever vaccination with STAMARIL will continue to be available into 2021. Recognizing the importance of yellow fever vaccination for military personnel and international travelers, Sanofi Pasteur has been working with U.S. FDA, CDC, DOD, and other stakeholders since 2016 so that vaccination against yellow fever remains available for travelers, U.S. government employees, military, and other response groups during the anticipated shortage period.'

December 23, 2020 - The WHO announced between 6 November and 15 December 2020, 52 suspected cases of yellow fever, including 14 deaths, were reported in Guinea. Guinea is a high-risk endemic country according to the EYE (Eliminate Yellow fever Epidemics) global strategy classification. Thus, the government implements routine vaccination for nine months of age, international travelers and organizes preventive and response campaigns according to the epidemiological context. However, according to WHO-UNICEF estimates, the vaccination coverage against yellow fever in Guinea has been 40% from 2016 to 2019, beneath the level necessary to sustain population immunity. In addition, a yellow fever vaccination survey in the Koundara district community found that coverage is deficient (16%). 

December 22, 2020 - VOA reported, 'More than 170 people have died from yellow fever outbreaks in Nigeria this year, despite vaccines being available since 2004. Some Nigerians prefer traditional herbal medicine as part of the problem. Experts say apathy to vaccines in rural areas is the biggest challenge, as Ifiok Ettang reports from Bauchi, Nigeria.

December 22, 2020 – In line with the Eliminate Yellow Fever Epidemics (EYE) strategy to prevent the international spread of yellow fever, the World Health Organization (WHO) donated 2 000 doses of yellow fever vaccine to South Sudan's Ministry of Health to provide protection against the yellow fever virus for international travelers and those living in areas where the disease is present.

December 11, 2020 - The WHO reported Ethiopia conducted a reactive yellow fever vaccination campaign to protect communities around an affected district. A yellow fever vaccination campaign targeting 700 000 people in Southern Nations, Nationalities and Peoples (SNNP), and Oromia regions was conducted in November 2020, achieving 93% of the target. The campaign aimed to stop the spread of an outbreak first reported in Enor-Ener Woreda in the Gurage Zone of SNNPR by vaccinating eligible age groups in 12 woredas (districts), one of them in Oromia, that were identified as potential epicenters of the outbreak. In addition, a first reactive campaign was conducted in 17 kebeles (sub-districts) of Enor-Ener in March 2020 when the outbreak occurred, bringing the outbreak quickly under control. 

December 3, 2020 - The K.U. Leuven research institution in The Netherlands announced their partnership on developing a vector-based COVID-19 vaccine candidate. The vector is derived from the live-attenuated yellow fever vaccine (YF17D strain), a proven safe and effective vaccine used worldwide to protect more than 500 million people against yellow fever. The YF17D-SARS-CoV-2 vaccine candidate, tentatively named RegaVax, shows convincing pre-clinical immunogenicity and efficacy data in challenge studies.

December 2, 2020 - RESEARCH ARTICLE: Consumptive coagulopathy of severe yellow fever occurs independently of hepatocellular tropism and massive hepatic injury. By examining clotting parameters in this model, we determined that hepatocyte infection alone is insufficient to cause the activation and consumption of coagulation factors observed in severe yellow fever cases in humans and nonhuman primates.

November 30, 2020 - The U.S. CDC issued a Level 2 Travel Alert, which stated 'the Nigeria Centre for Disease Control (NCDC) is reporting yellow fever outbreaks in multiple states (Bauchi, Benue, Delta, Ebonyi, and Enugu) as confirmed by testing at the Nigerian National Reference Laboratory. Response activities are underway, and mass vaccination campaigns are planned in the affected areas. And the government of Nigeria requires that all travelers nine months of age or older show proof of yellow fever vaccination to enter the country. A signed and stamped International Certificate of Vaccination or Prophylaxis (ICVP or "Yellow Card") provides proof of vaccination.

November 2, 2020 - The Nigeria Centre for Disease Control (NCDC) reported to the WHO a cluster of deaths in the Ute Okpu community in the 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 48 suspected yellow fever cases (Y.F.) with 30 deaths (CFR 62.5%). The Y.F. 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 others, launched a reactive yellow fever vaccination campaign in Kajo, Keji, Central Equatoria State. The campaign aims to protect over 90,000 individuals aged nine 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 Senegal's Africa country 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 ten days before 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.

July 28, 2020 - Changing temperature and rainfall across Africa could increase yellow fever deaths by up to 25% by 2050. According to new modeling of yellow fever's burden 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. 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's 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. In addition, 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 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. OHSU will 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.

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

August 8, 2008 - The WHO stated 'Committee reiterated that the recommendations for yellow fever vaccine should remain unchanged. There needs to be careful adherence to the indications for vaccine use and assessment of the risks and benefits, including in special groups who have the potential risk of developing serious adverse events. The vaccine should be administered only to those travelers truly at risk of exposure. Further, in communicating safety risks, it should be acknowledged that risk-benefit ratios may differ for vaccination of travelers and vaccination of populations living in at-risk areas.'

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.

Polymerase chain reaction testing in blood and urine can sometimes detect the virus in the early stages of the disease. However, in later stages, testing to identify antibodies is needed. The U.S. CDC publishes a list of frequently asked questions and answers found on 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 reviewed by healthcare providers, such as Dr. Robert Carlson.