yellow fever vaccine

Action and Spectrum

Actions and Spectrum: 

• The yellow fever vaccine is a live attenuated vaccine that stimulates the immune system to produce a protective response against the yellow fever virus. The vaccine contains a weakened but still live strain of the virus that cannot cause disease in healthy individuals but can still stimulate the immune system. 

• The mechanism of action of the yellow fever vaccine involves the activation of both innate and adaptive immune responses. The virus in the vaccine enters host cells and replicates, leading to the production of viral antigens that are presented to the immune system. This triggers the activation of innate immune cells, such as macrophages and dendritic cells, and adaptive immune cells, such as T and B lymphocytes. 

• The vaccine produces neutralizing antibodies that can prevent infection with the wild-type virus. It also activates cellular immune responses, including T-cell responses, that can control and clear viral infections. 

• The spectrum of activity of the yellow fever vaccine is broad, as it protects against the yellow fever virus, a flavivirus transmitted by mosquitoes. The vaccine is effective against all known virus strains and can provide lifelong immunity in most individuals. The vaccine is recommended for individuals who live in or travel to areas where yellow fever is endemic or where outbreaks have occurred. 

Drug Interaction

Adverse Reaction

Frequency defined 

1-10% 

Chills (5-10%) 

Myalgia (5-10%) 

Headache (5-10%) 

Low-grade fever (5-10%)  

Frequency not defined 

Seizures 

Urticaria 

Warmth 

Guillain-Barre syndrome 

Meningoencephalitis 

Rash 

Pain 

Erythema 

Black Box Warning

Contraindication / Caution

Contraindications/caution: 

Contraindications: 

• Severe allergic reaction to a previous dose of the yellow fever vaccine or any of its components, such as egg proteins or gelatin. 

• Severe allergic reaction to a substance like a vaccine component, such as other flaviviruses or thimerosal. 
• Severe immunodeficiencies, such as primary immunodeficiency, HIV/AIDS with severe immunosuppression, leukemia, lymphoma, or other malignancies affecting the immune system. 
• Pregnancy or breast-feeding, unless there is a high risk of yellow fever infection. 

• Age younger than six months, as the vaccine has not been approved for use in this age group. 

• Moderate or severe acute illness, as the vaccine, may exacerbate symptoms or interfere with the immune response. 

• Current or recent treatment with immunosuppressive drugs, such as chemotherapy, corticosteroids, or radiation therapy. 

Caution: 

• Age: The yellow fever vaccine is not recommended for infants under six months of age. It is also associated with an increased risk of adverse events in people over 60. 

• Immunocompromised individuals: People who are immunocompromised, including those with HIV, cancer, or other conditions that affect the immune system, may have a reduced response to the vaccine and may not be fully protected against yellow fever. These individuals should discuss the risks and benefits of vaccination with their healthcare provider. 

• Allergies: While severe allergic reactions to the yellow fever vaccine are rare, people with a history of severe allergies to any vaccine component, including eggs and gelatin, should discuss the risks and benefits of vaccination with their healthcare provider. 

• Pregnancy and breast-feeding: The yellow fever vaccine is generally not recommended for pregnant or breast-feeding women, except in certain circumstances where the risk of yellow fever infection is high. 

• Chronic medical conditions: People with certain chronic medical conditions, such as autoimmune disorders, kidney disease, or liver disease, may have a higher risk of adverse events from the vaccine and should discuss the risks and benefits of vaccination with their healthcare provider. 

• Travel plans: The yellow fever vaccine is recommended for people traveling to areas where yellow fever is endemic or where outbreaks have occurred. However, it is essential to note that some countries require proof of yellow fever vaccination for entry. Travelers should check the vaccination requirements for their destination before departure. 

Pregnancy / Lactation

Pregnancy consideration: The yellow fever vaccine is generally not recommended for pregnant or breast-feeding women, except in certain circumstances where the risk of yellow fever infection is high 

Lactation:  

The yellow fever vaccine can be given to breast-feeding women if they travel to an area where yellow fever is endemic or if the risk of yellow fever infection is high.  

The vaccine virus is not excreted in breast milk, and there is no evidence to suggest that breast-feeding after vaccination poses any risk to the infant. 

Pregnancy category: 

Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.   

Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category 

Pharmacology

Pharmacology: 

• The yellow fever vaccine is live attenuated, which means it contains a weakened form of the yellow fever virus modified to be less virulent and less likely to cause disease. The vaccine is administered by injection and works by stimulating the body’s immune system to produce a protective response against the virus. 

• After the vaccine is injected, the weakened virus replicates in the body, triggering an immune response. The immune system produces antibodies that recognize and neutralize the virus and T cells that destroy infected cells. These immune responses protect against future exposure to the virus. 

• The yellow fever vaccine is highly effective in preventing yellow fever infection. Studies have demonstrated that a single dose of the vaccine provides long-lasting protection, with immunity lasting for at least ten years and possibly for life. 

• The yellow fever vaccine also produces some side effects, including mild fever, headache, muscle pain, and soreness at the injection site. These side effects are usually mild and go away within a few days. Serious side effects are rare but can occur, particularly in people with weakened immune systems. 

• In summary, the yellow fever vaccine is a live attenuated vaccine that stimulates the body’s immune system to produce a protective response against the yellow fever virus. The vaccine is highly effective in preventing yellow fever infection but can also produce mild side effects 

Pharmacodynamics: 

• yellow fever vaccine works by stimulating the body’s immune system to produce protective antibodies against the yellow fever virus. This is achieved by introducing a weakened or attenuated strain of the yellow fever virus into the body. 

• The vaccine contains live, attenuated yellow fever virus that replicates in the body, triggering the production of antibodies that recognize and neutralize the virus. The immune response involves the activation and proliferation of T-lymphocytes, responsible for recognizing and destroying infected cells, and the production of specific antibodies that can bind to and inactivate the virus. 

• Once the vaccine is administered, the virus replicates in the lymphatic system and stimulates the production of antibodies. This process takes several days, during which the individual may experience mild symptoms such as headache, low-grade fever, and muscle aches. These symptoms are usually mild and self-limited, indicating that the immune system responds to the vaccine. 

Pharmacokinetics: 

Absorption 

The yellow fever vaccine is typically administered via subcutaneous injection, which is injected under the skin. After injection, the vaccine is absorbed into the bloodstream and transported to the lymphatic system, stimulating an immune response. 

Distribution 

Once in the bloodstream, the yellow fever vaccine is distributed throughout the body. The vaccine virus replicates primarily in the lymphatic tissue, triggering the production of antibodies and T-lymphocytes. 

Metabolism 

The yellow fever vaccine is a live, attenuated virus, which means that it can replicate in the body but has been weakened so that it does not cause disease. The virus is metabolized in the body through normal viral replication processes, and the immune system recognizes and eliminates the resulting viral particles. 

Elimination and Excretion 

The yellow fever vaccine is eliminated from the body primarily through the immune response. As the vaccine virus replicates and is recognized by the immune system, it is neutralized and eliminated from the body. There is no significant excretion of the vaccine virus through urine or feces. 

Adminstartion

Administration: 

yellow fever vaccine is typically administered via subcutaneous injection, which is injected under the skin. The recommended dose for adults and children over nine months of age is 0.5 mL, which contains a live, attenuated strain of the yellow fever virus. 

The vaccine should be administered at least ten days before traveling to an area where yellow fever is endemic to ensure adequate protection against the virus. It is important to note that the vaccine is not recommended for certain groups of people, including infants under nine months of age, pregnant women, and individuals with weakened immune systems. 

In some cases, a booster dose of the vaccine may be recommended, particularly for individuals who received their initial dose more than ten years ago. The vaccine can be administered simultaneously as other vaccines but should be given in a different location on the body to avoid cross-contamination. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: yellow fever vaccine 

Why do we use yellow fever vaccine? 

The primary use of the yellow fever vaccine is to prevent yellow fever, a viral disease transmitted by infected mosquitoes. The vaccine is highly effective in preventing yellow fever and is recommended for individuals traveling to areas where the disease is endemic or at risk for outbreaks. 

In addition to its use for travel-related purposes, the yellow fever vaccine may also be recommended for individuals who work in laboratories or other settings where they may be at risk of exposure to the virus.

The vaccine may also be recommended for individuals at increased risk of complications from yellow fever, such as those with weakened immune systems or other medical conditions.