VACCINE AWARENESS RAISING FOUNDATION AFRICA
YELLOW FEVER (YF)
Yellow fever is a Flavivirus, a single-stranded RNA virus transmitted via mosquito bites. Symptoms, appearing 3–6 days post-infection, encompass fever, chills, headache, backache, and muscle aches. Roughly 15% of cases progress to severe illness, with potential complications such as bleeding, shock, organ failure, and, in some instances, fatal outcomes.
Sanofi.com
“Yellow fever is a viral hemorrhagic fever that is transmitted by mosquitoes."
YELLOW FEVER IN AFRICA
Yellow Fever is endemic and periodically epidemic in sub-Saharan Africa and tropical South America. High-risk countries for exposure to the virus include Angola, Benin, Burkina Faso, Cameroon, Central Africa, Chad, Congo, Ivory Coast, Congo DRC, Equatorial Guinea, Ethiopia, Gabon, The Gambia, Ghana, Guinea, Guinea Bissau, Kenya, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, South Sudan, Sudan, Togo, and Uganda. Conversely, countries with low potential for exposure are Eritrea, Rwanda, São Tomé and Príncipe, Somalia, Tanzania, and Zambia.
YELLOW FEVER SYMPTOMS
TRANSMISSION
Yellow Fever virus has three transmission cycles: sylvatic (jungle), intermediate (savannah), and urban. The sylvatic cycle involves transmission between nonhuman primates and forest canopy mosquitoes, posing a risk during activities encroaching into the jungle. In the African intermediate cycle, YF virus is transmitted from tree hole-breeding Aedes spp. to humans in jungle border areas. The urban cycle involves virus transmission between humans and peridomestic mosquitoes. Humans with YF virus have peak viremia levels just before fever onset, lasting 3–5 days, allowing transmission to mosquitoes.
TREATMENT
Treatment for Yellow Fever is focused on symptomatic relief and life-saving interventions, including rest, fluids, and analgesics/antipyretics for aching and fever. Caution is needed with medications like aspirin or nonsteroidal anti-inflammatory drugs due to an increased risk of bleeding. Infected individuals should be protected from mosquito exposure during the initial days of illness to prevent further transmission. This can be achieved by staying indoors or using a mosquito net.
PREVENTION
To prevent mosquito-borne diseases, including Yellow Fever, the best approach is to avoid mosquito bites. Additionally, a relatively safe and effective vaccine is available for Yellow Fever prevention.
VACCINATION
All currently manufactured Yellow Fever vaccines are live attenuated viral vaccines. In the United States, YF-Vax by Sanofi Pasteur is the only licensed Yellow Fever vaccine. During a YF-Vax shortage from late 2015 to April 2021, Sanofi Pasteur imported and sold Stamaril, a Yellow Fever vaccine manufactured in France, under an expanded-access investigational new drug protocol.
TARGET GROUP
The Yellow Fever vaccine is recommended for individuals aged ≥9 months traveling to or residing in regions with Yellow Fever virus transmission in South America and Africa. Additionally, some countries mandate proof of Yellow Fever vaccination for entry. For specific vaccination recommendations and requirements by country, refer to country-specific guidelines.
WHO
"A single dose of vaccine can provide lifelong protection against yellow fever."
YELLOW FEVER INITIATIVES
The initiative to enhance yellow fever diagnostic capacity across Africa, supported by Gavi, the Vaccine Alliance, and various partners, has significantly improved diagnostics on the continent. Gavi's funding of $8.2 million in 2018 for diagnostic equipment and supplies, along with $5.3 million for strengthening lab capacity in 24 African countries for 2019-21, complements larger investments in yellow fever vaccination. While diagnostics are crucial for prevention, additional initiatives for vaccination are essential to curb yellow fever outbreaks.