Yellow fever vaccine
Encyclopedia
Yellow fever vaccine is a vaccine
used against yellow fever
.
The vaccine consists of a live, but attenuated, strain of the yellow fever virus called 17D. The 17D vaccine has been used commercially since the 1950s. The mechanisms of attenuation and immunogenicity
for the 17D strain are not known. However, this vaccine is very safe, with few adverse reactions having been reported and millions of doses administered, and highly effective with over 90% of vaccinees developing a measurable immune response after the first dose. Yellow fever vaccination certificate is issued for 10 years but becomes valid only after 10 days of vaccination.
, working at the Rockefeller Foundation
, developed a safe and highly efficacious vaccine
for yellow fever that gives a ten-year or more immunity from the virus. For his work on the yellow fever vaccine, he received the 1951 Nobel Prize in Physiology or Medicine.
The majority of adverse reactions to the 17D vaccine result from allergic reaction to the eggs in which the vaccine is grown. Persons with a known egg allergy
should discuss this with their physician prior to vaccination. In addition, there is a small risk of neurologic disease and encephalitis
, particularly in individuals with compromised immune system
s and very young children. The 17D vaccine is contraindicated in infants, pregnant women, breast-feeding women and anyone with a diminished immune capacity, including those taking immunosuppressant drugs.
According to the travel clinic at the University of Utah Hospital, the vaccine presents an increased risk of adverse reaction in adults aged 60 and older, with the risk increasing again after age 65, and again after age 70. The reaction is capable of producing multiple organ failure and should be evaluated carefully by a qualified health professional before being administered to the elderly.
There is a small risk of more severe yellow fever-like disease associated with the vaccine. This reaction, called YEL-AVD, causes a fairly severe disease closely resembling yellow fever caused by virulent strains of the virus. The risk factor/s for YEL-AVD are not known, although it has been suggested that it may be genetic. The 2`-5` oligoadenylate synthetase (OAS) component of the innate immune response has been shown to be particularly important in protection from Flavivirus infection. In at least one case of YEL-AVD, the patient was found to have an allelic mutation in a single nucleotide polymorphism
(SNP) of the OAS gene.
The Canadian Medical Association published a 2001 CMAJ article entitled "Yellow fever vaccination: be sure the patient needs it". The article begins by stating that of the 7 people who developed system failure within 2 to 5 days of the vaccine in 1996-2001, 6 died "including 2 who were vaccinated even though they were planning to travel to countries where yellow fever has never been reported." The article cites that "3 demonstrated histopatholic changes consistent with wild yellow fever virus." The author recommends vaccination for only non-contraindicated travelers (see the articles list) and those travellers going where yellow fever activity is reported or in the endemic zone which can be found mapped at the CDC website cited below. In addition, the 2010 online edition of the Center for Disease Control Traveler's Health Yellow Book that between 1970-2002 only "nine cases of yellow fever were reported in unvaccinated travelers from the United States and Europe who travelled" to West Africa and South America, and 8 of the 9 died. However, it goes on to state that of travelers "only one documented case of yellow fever has occurred, which was in a vaccinated traveler from Spain...in 1988". c",)
s, protective clothing, and screening of houses are helpful, but not always sufficient for mosquito control; people should always use an insecticide spray while in certain areas. In affected areas, mosquito control
methods have proven effective in decreasing the number of cases.
Vaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
used against yellow fever
Yellow fever
Yellow fever is an acute viral hemorrhagic disease. The virus is a 40 to 50 nm enveloped RNA virus with positive sense of the Flaviviridae family....
.
The vaccine consists of a live, but attenuated, strain of the yellow fever virus called 17D. The 17D vaccine has been used commercially since the 1950s. The mechanisms of attenuation and immunogenicity
Immunogenicity
Immunogenicity is the ability of a particular substance, such as an antigen or epitope, to provoke an immune response in the body of a human or animal.- Immunogenicity :The ability to induce humoral and/or cell-mediated immune responses....
for the 17D strain are not known. However, this vaccine is very safe, with few adverse reactions having been reported and millions of doses administered, and highly effective with over 90% of vaccinees developing a measurable immune response after the first dose. Yellow fever vaccination certificate is issued for 10 years but becomes valid only after 10 days of vaccination.
History
In 1937, Max TheilerMax Theiler
Max Theiler was a South African/American virologist. He was awarded the Nobel Prize in Physiology or Medicine in 1951 for developing a vaccine against yellow fever.-Career development:...
, working at the Rockefeller Foundation
Rockefeller Foundation
The Rockefeller Foundation is a prominent philanthropic organization and private foundation based at 420 Fifth Avenue, New York City. The preeminent institution established by the six-generation Rockefeller family, it was founded by John D. Rockefeller , along with his son John D. Rockefeller, Jr...
, developed a safe and highly efficacious vaccine
Vaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
for yellow fever that gives a ten-year or more immunity from the virus. For his work on the yellow fever vaccine, he received the 1951 Nobel Prize in Physiology or Medicine.
Risks
Although the vaccine is considered safe, there are risks involved.The majority of adverse reactions to the 17D vaccine result from allergic reaction to the eggs in which the vaccine is grown. Persons with a known egg allergy
Egg allergy
Egg allergy is a type of food allergy. It is a hypersensitivity to dietary substances from the yolk or whites of eggs, causing an overreaction of the immune system which may lead to severe physical symptoms for millions of people around the world....
should discuss this with their physician prior to vaccination. In addition, there is a small risk of neurologic disease and encephalitis
Encephalitis
Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...
, particularly in individuals with compromised immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
s and very young children. The 17D vaccine is contraindicated in infants, pregnant women, breast-feeding women and anyone with a diminished immune capacity, including those taking immunosuppressant drugs.
According to the travel clinic at the University of Utah Hospital, the vaccine presents an increased risk of adverse reaction in adults aged 60 and older, with the risk increasing again after age 65, and again after age 70. The reaction is capable of producing multiple organ failure and should be evaluated carefully by a qualified health professional before being administered to the elderly.
There is a small risk of more severe yellow fever-like disease associated with the vaccine. This reaction, called YEL-AVD, causes a fairly severe disease closely resembling yellow fever caused by virulent strains of the virus. The risk factor/s for YEL-AVD are not known, although it has been suggested that it may be genetic. The 2`-5` oligoadenylate synthetase (OAS) component of the innate immune response has been shown to be particularly important in protection from Flavivirus infection. In at least one case of YEL-AVD, the patient was found to have an allelic mutation in a single nucleotide polymorphism
Single nucleotide polymorphism
A single-nucleotide polymorphism is a DNA sequence variation occurring when a single nucleotide — A, T, C or G — in the genome differs between members of a biological species or paired chromosomes in an individual...
(SNP) of the OAS gene.
The Canadian Medical Association published a 2001 CMAJ article entitled "Yellow fever vaccination: be sure the patient needs it". The article begins by stating that of the 7 people who developed system failure within 2 to 5 days of the vaccine in 1996-2001, 6 died "including 2 who were vaccinated even though they were planning to travel to countries where yellow fever has never been reported." The article cites that "3 demonstrated histopatholic changes consistent with wild yellow fever virus." The author recommends vaccination for only non-contraindicated travelers (see the articles list) and those travellers going where yellow fever activity is reported or in the endemic zone which can be found mapped at the CDC website cited below. In addition, the 2010 online edition of the Center for Disease Control Traveler's Health Yellow Book that between 1970-2002 only "nine cases of yellow fever were reported in unvaccinated travelers from the United States and Europe who travelled" to West Africa and South America, and 8 of the 9 died. However, it goes on to state that of travelers "only one documented case of yellow fever has occurred, which was in a vaccinated traveler from Spain...in 1988". c",)
Candidates for vaccination
People most at risk of contracting the virus should be vaccinated. Woodcutters working in tropical areas should be particularly targeted for vaccination. InsecticideInsecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
s, protective clothing, and screening of houses are helpful, but not always sufficient for mosquito control; people should always use an insecticide spray while in certain areas. In affected areas, mosquito control
Mosquito control
Mosquito control manages the population of mosquitoes to reduce their damage to human health, economies, and enjoyment. Mosquito control is a vital public-health practice throughout the world and especially in the tropics because mosquitoes spread many diseases, such as malaria.Mosquito-control...
methods have proven effective in decreasing the number of cases.