Yellow Fever Vaccine

Approved Uses:

• Active immunization against yellow fever virus infection in individuals aged ≥9 months, particularly:
• Travelers to endemic areas (sub-Saharan Africa and South America)
• Residents of yellow fever endemic regions
• Individuals requiring vaccination for international travel certification under the International Health Regulations (IHR)
• People at occupational risk (e.g., laboratory workers handling yellow fever virus)

Clinically Accepted Off-Label Uses:

• Emergency use during epidemics and outbreak containment
• Use in 6–8 month-old infants when the risk of exposure is high and outweighs the risk of vaccination
• Re-vaccination (booster) in immunocompromised or high-exposure individuals, although a single dose typically provides lifelong immunity

রেজিস্টার্ড চিকিৎসকের নির্দেশনা অনুযায়ী ঔষধ সেবন করুন।

Formulation:

• Live attenuated 17D strain
• Supplied as a lyophilized powder with diluent for reconstitution

Dose:

• 0.5 mL single subcutaneous injection

Age Group Recommendations:

• ≥9 months: Standard dose (0.5 mL SC), provides long-term immunity
• 6–8 months: Only in high-risk exposure scenarios with caution
• <6 months: Contraindicated due to risk of post-vaccine encephalitis

Booster Doses:

• Not routinely needed (WHO recommendation)
• Consider for:
• Travelers to high-risk areas if vaccinated >10 years ago and at continued exposure risk
• Individuals with HIV or other immunocompromising conditions

Administration Notes:

• Administer at least 10 days prior to travel
• Subcutaneous route preferred; intramuscular acceptable if subcutaneous is not feasible

রেজিস্টার্ড চিকিৎসকের নির্দেশনা অনুযায়ী ঔষধ সেবন করুন।

The Yellow Fever Vaccine contains a live attenuated 17D strain of the yellow fever virus, which replicates locally at the injection site and in lymphoid tissues. This replication stimulates a robust immune response, producing neutralizing antibodies and activating both humoral and cellular immunity. These immune responses mimic natural infection, conferring long-lasting protection—often lifelong—against wild-type yellow fever virus upon future exposure.

As a live viral vaccine, traditional pharmacokinetics (absorption, distribution, metabolism, excretion) do not apply. Instead, the 17D virus:

• Replicates at the local injection site and regional lymph nodes
• Is detectable in blood within 4–6 days post-vaccination
• Peak viremia occurs around day 5–7, declining as neutralizing antibodies are produced
• Induces protective immunity typically within 10 days, with sustained antibody titers persisting for decades or lifelong in most individuals

Pregnancy:

• Live vaccine; generally contraindicated during pregnancy unless travel to high-risk areas is unavoidable
• If unavoidable, may be given in the second or third trimester after risk-benefit evaluation
• Some case reports suggest low risk, but caution is warranted

Lactation:

• Live virus may be secreted in breast milk
• Risk of transmitting vaccine virus to infants under 6 months
• Avoid breastfeeding for at least 2 weeks post-vaccination in such cases if alternative feeding is possible

• Vaccine
• Subclass: Live attenuated viral vaccine
• Specific: Flavivirus vaccine

• Known hypersensitivity to egg proteins, gelatin, or any vaccine component
• Age <6 months
• History of thymus disease (e.g., thymoma, myasthenia gravis)
• Severe immunodeficiency (e.g., due to HIV/AIDS, chemotherapy, high-dose corticosteroids)
• Current febrile illness or acute severe infection

• Age >60 years: Increased risk of serious adverse events (e.g., viscerotropic disease)
• Infants 6–8 months: Increased risk of encephalitis
• Use caution in:
• HIV-positive individuals (CD4 count <200: contraindicated; 200–499: caution)
• Patients with autoimmune or thymic disorders
• Breastfeeding mothers of infants <6 months
• Monitor for signs of:
• Yellow fever vaccine-associated viscerotropic disease (YEL-AVD)
• Neurotropic disease (YEL-AND) (e.g., meningoencephalitis)

Common:

• Local: Pain, redness, swelling at injection site
• Systemic: Fever, headache, malaise, myalgia

Uncommon to Rare:

• Anaphylaxis
• Yellow fever vaccine-associated viscerotropic disease (YEL-AVD) – rare but potentially fatal, resembles wild-type yellow fever
• Neurotropic adverse events (YEL-AND) – meningoencephalitis, Guillain-Barré syndrome
• Hypersensitivity reactions due to egg protein or gelatin

Timing:

• Mild symptoms within 3–5 days post-vaccination
• Serious adverse events typically occur within 10 days

• Immunosuppressants (e.g., corticosteroids, chemotherapy):
• May reduce vaccine efficacy
• Increased risk of adverse events
• Other live vaccines:
• Administer simultaneously or ≥4 weeks apart
• Antiviral drugs (e.g., ribavirin):
• May impair live virus replication and thus immune response
• No known CYP450 interactions as this is a vaccine, not a drug metabolized via hepatic enzymes

• WHO (2013): Single dose confers lifelong immunity—boosters not routinely required
• CDC (2021): Recommends booster in select individuals with ongoing exposure risk or immunocompromise
• IHR (2022): International Certificate of Vaccination valid for life, effective 10 days after vaccination

• Store at 2°C to 8°C (Refrigerated; Do not freeze)
• Protect from light
• Reconstitute with provided diluent immediately before use
• Use reconstituted vaccine within 60 minutes
• Shake gently before use
• Do not use after expiration or if vaccine appears cloudy