Japanese encephalitis virus vaccine

Action and Spectrum

Actions and Spectrum 

Action: 

Prevention of Infection: The vaccine stimulates the production of antibodies against the Japanese encephalitis virus. When an individual who has received a vaccination comes into contact with the virus, the antibodies present in their system can effectively neutralize the virus, thereby opposing its ability to invade and infect the cells of the body. This preventive action of the vaccine plays a crucial role in minimizing the transmission of the virus among the general population. 

Reduction of Disease Severity: In cases where a vaccinated individual does become infected with the Japanese encephalitis virus, the vaccine can still provide benefits. Vaccinated individuals are likely to experience milder symptoms and a lower risk of developing severe complications compared to those who are unvaccinated. This reduction in disease severity is crucial, as Japanese encephalitis can be a severe and potentially life-threatening illness. 

Spectrum  

It primarily targets protection against Japanese encephalitis virus infection. The vaccine is specifically designed to provide immunity against the Japanese encephalitis virus serotype 3, which is the most common cause of the disease. 

However, it also offers some cross-protection against other serotypes of the virus, providing a broader spectrum of coverage. It’s worth noting that the JEV vaccine is usually recommended for individuals living in or traveling to areas where Japanese encephalitis is endemic or where outbreaks have occurred.  

Drug Interaction

Adverse Reaction

Frequency defined  

>10% 

Infants 2 month to <1 year 

Diarrhea (8.4-11.5%) 

Irritability (8.4-15.3%) 

Injection site redness (5.3-17.6%) 

Fever, 99.9-101.5°F (12.2-17.6%) 

Children 1 year to <3 years 

Injection pain (6.7-15%) 

Adolescents 12 years to <18 years 

Fever, 99.9-101.5F (8.5-15.6%) 

Adults ≥18 years 

Influenzalike illness (12.3%) 

Fatigue (11.3%) 

Myalgia (15.6%) 

Headache (27.9%) 

1-10% 

Infants 2 month to <1 year 

Vomiting (3.8-7.6%) 

Injection site swelling (1.5%) 

Excessive fatigue (1.5-3.1%) 

Fever, 101.6-102.7°F (1.5-6.1%) 

Loss of appetite (5.3%) 

Rash (3.8-8.4%) 

Injection site tenderness (0.8-3.1%) 

Children 1 year to <3 years 

Vomiting (2.8-4.2%) 

Injection site pain (3.6%) 

Rash (1.3-4.2%) 

Injection site redness (2.5-6.1%) 

Fever, 101.6-102.7°F (2.5-3%) 

Loss of appetite (2.5-5.6%) 

Diarrhea (4.6-7%) 

Children 3 years to <12 years 

Flulike symptoms (0.3-1.4%) 

Rash (1%) 

Loss of appetite (1%) 

Headache (1.4-3.8%) 

Injection site pain or tenderness (1.7-5.5%) 

Vomiting (0.7-1.7%) 

Fever, 99.9-101.5°F (3.3-7.7%) 

Adolescents 12 years to <18 years 

Vomiting (1.3%) 

Injection site tenderness (0.4-10%) 

Nausea (2.1%) 

Headache (3.4-4.6%) 

Muscle pain (1.3-2.9%) 

Fever, 99.9-101.5°F (3.3-3.8%) 

Irritability (2.1%) 

Flulike symptoms (1.3-3.3%) 

Adults ≥18 years 

Vomiting (1.4%) 

Fever (3.2%) 

Pharyngolaryngeal pain (1.6%) 

URI (1.7%) 

Diarrhea (1.5%) 

Nasopharyngitis (4.7%) 

Nausea (6.6%) 

Rhinitis (1.4%) 

<1% 

Infants 2 month to <1 year 

Fever, 102.8-104.9°F (0.8%) 

Children 1 year to <3 years 

Fever, >104.9°F (0.2%) 

Black Box Warning

Black Box Warning:  

None

Contraindication / Caution

Contraindication/Caution:  

Allergy: If an individual has had a severe allergic reaction (anaphylaxis) to a previous dose of the Japanese encephalitis vaccine or any of its components, they should not receive the vaccine. 

Hypersensitivity: Individuals who have a known hypersensitivity to any element of the Japanese encephalitis vaccine should not receive it. This includes allergies to any ingredient of the vaccine, such as proteins, preservatives, or stabilizers. 

Severe illness: Vaccination should be postponed in individuals who are acutely ill with a moderate or severe fever. It is advisable to wait until the person recovers from the illness before administering the vaccine. 

Pregnancy: It is generally advised against administering the Japanese encephalitis vaccine to pregnant individuals, unless the potential advantages outweigh the associated risks. In situations where traveling to an area where the disease is prevalent is unavoidable, it is crucial to consult with a healthcare professional who can carefully evaluate the risks and benefits before making a decision. 

Immunosuppression: Individuals who are severely immunocompromised, such as those undergoing chemotherapy, radiation therapy, or taking immunosuppressive medications, may have a diminished immune response to the vaccine. In such cases, the vaccine may be less effective, and the decision to vaccinate should be made in consultation with a healthcare provider. 

Pregnancy / Lactation

Pregnancy warnings:     

Pregnancy category: AU TGA pregnancy category: B1
US FDA pregnancy category: B 

Lactation: Excreted into human milk is unknown 

Pregnancy Categories:         

Category A: Studies that were well-controlled and met expectations revealed no risk to the fetus in either the first or second trimester. 

Category B: There were a lack of studies on pregnant women and no evidence of risk to the fetus in animal experiments.   

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 Japanese encephalitis virus (JEV) vaccine is a vaccine that provides protection against Japanese encephalitis, a viral disease caused by the Japanese encephalitis virus. 

Pharmacodynamics:  

Japanese encephalitis virus vaccine involve the activation of the immune system, leading to the production of specific antibodies and the generation of memory B and T cells. These immune responses provide protection against the Japanese encephalitis virus, reducing the risk and severity of infection if exposed to the actual virus.   

Pharmacokinetics: 

Absorption 

Once injected, the vaccine is absorbed into the bloodstream. The vaccine contains inactivated JEV antigens, which trigger an immune response in the body. 

Distribution 

Once in the bloodstream, the JEV vaccine antigens are distributed throughout the body. The antigens interact with immune cells, particularly antigen-presenting cells such as dendritic cells, which play a crucial role in initiating an immune response. 

Metabolism 

As a vaccine, the JEV antigens are not metabolized in the same way as drugs. However, within the body, the antigens are recognized by the immune system, which initiates a complex series of metabolic processes.  

Excretion and Elimination 

The vaccine does not undergo traditional excretion from the body. once the immune response is initiated, the immune cells recognize and neutralize the JEV antigens. Antibodies are produced, and immunological memory is established to provide long-term protection against JEV infection. 

Adminstartion

Administration:  

Schedule: The vaccine is typically given in a two-dose series, with the doses administered a few weeks apart. In some cases, a booster dose may be required based on individual risk factors and previous vaccination history. 

Injection: The vaccine is given as an intramuscular injection, usually in the upper arm for adults and older children. for infants, it may be administered in the anterolateral 5thigh muscle. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: Japanese encephalitis virus vaccine 

Why do we use Japanese encephalitis virus vaccine?  

Preventing Japanese Encephalitis: The primary purpose of the Japanese encephalitis virus vaccine is to prevent the occurrence of Japanese encephalitis. This disease is caused by the Japanese encephalitis virus, which is transmitted through mosquito bites, particularly in rural and agricultural areas of Asia. Vaccination can significantly reduce the risk of acquiring this potentially life-threatening infection. 

Protection for Travelers: The Japanese encephalitis vaccine is recommended for travelers who plan to visit or reside in areas where Japanese encephalitis is endemic or prevalent. This includes countries in East Asia, South Asia, and Southeast Asia, such as Japan, China, South Korea, India, Thailand, and Vietnam.  

Military Personnel Deployments: Japanese encephalitis vaccination is often a requirement for military personnel, especially those deployed to regions where Japanese encephalitis is endemic. Vaccinating military personnel helps to protect them from the disease and ensures their readiness during deployments. 

Outbreak Control Measures: In the event of an outbreak or increased transmission of Japanese encephalitis, vaccination campaigns may be conducted as part of public health measures.