Yellow fever Vaccine
المؤلف:
Baijayantimala Mishra
المصدر:
Textbook of Medical Virology
الجزء والصفحة:
2nd Edition , p296
2025-12-21
12
In 1930, two YF vaccines—17D and French neurotropic vaccines were developed. The later one was produced in mouse brain and was discontinued since 1982 due to its association with high incidence of post-vaccinal encephalitis. Whereas 17D is considered as one of the safest and effective vaccines ever developed for which Max Theiler got Nobel Prize in 1951.
All currently available YF vaccines are live attenuated vaccines derived from 17D lineage. The vaccine was derived from a wild type virus isolated in 1927 in Ghana from a man with febrile illness. The strain is called “Asibi”strain which was passaged 176 times in mice and chicken tissues to produce the attenuated 17D vaccine virus. This vaccine virus has two substrains—17DD and 17D-204. Both the substrains share 99.9% of sequence homology. The vaccine virus 17D differs from the original Asibi strain by 20 amino acids. It has substantially reduced viscerotropic and neurotropic properties and non-transmissible by mosquitoes.
WHO recommendations for YF 17D vaccine:
• The recommended immunizing dose should not contain less than 3.0 log 10 international unit.
• Storage temperature is 2–8°C, present in lyophilised form, should be reconstituted using sterile diluent and discarded after 1–6 hours.
• Given subcutaneously or intramuscularly.
• Age group: >9 months.
• Should be given to all children at 9–12 months of age in endemic countries and to all unvaccinated travellers going to or coming from the endemic or at-risk countries.
• Single dose is recommended. (The re commendation of booster dose after 10 years has been stopped since June 2016 except in high-risk groups such as pregnant women and immunocompromised individuals, etc. as the vaccine provides lifelong immunity.) However, the policy differs in different countries.
• India has agreed to WHO recommendation of single dose vaccination policy for international travellers from endemic countries since August 2017.
Immunogenicity of vaccine: Yellow fever 17D vaccine induces rapid and effective immune response. Protective level of neutralizing antibodies develops in 80% of vaccine within 10 days, in 90% by 2 weeks and in 100% by 4 weeks post-vaccination.
Adverse events: Mild symptoms including headache, myalgia with local site side effects are seen in around 25%. Serious adverse events can be:
i. Anaphylactic reaction: Reported in about 0.8 in 100,000 vaccinations.
ii. YF associated neurologic diseases leading to symptoms like Guillain-Barre syndrome (GBS), reported in 0.25–0.8 in 100,000 vaccinations.
iii. YF associated viscerotropic diseases leading to multi-organ dysfunction, reported in 0.25–0.4 in 100,000 vaccinations.
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