What is Journvax (vaccine)?

Japanese Encephalitis Vaccine (JE-VC): IXIARO/JESPECT

JournVax is not a recognized vaccine name in medical literature or approved by regulatory agencies. Based on the available evidence, there is no vaccine with this specific name. The only licensed Japanese encephalitis (JE) vaccine currently available in the United States is JE-VC, marketed under the brand name Ixiaro 1.

Overview of Japanese Encephalitis Vaccines

Japanese encephalitis (JE) is a mosquito-borne viral disease endemic in many parts of Asia. The currently available vaccines include:

• JE-VC (Ixiaro): An inactivated Vero cell culture-derived vaccine, which is the only JE vaccine licensed and available in the United States 1
• JE-MB (JE-VAX): An inactivated mouse brain-derived vaccine that was previously available in the United States but is no longer produced (all doses expired in May 2011) 1

Other JE vaccines available in different countries but not in the US include:

• Live attenuated vaccines
• Live recombinant (chimeric) vaccines
• Other inactivated Vero cell culture-derived vaccines 1

Mechanism of Protection

JE-VC works by inducing JE virus neutralizing antibodies, which is considered a reliable surrogate of efficacy 1. These neutralizing antibodies are:

• Genus-specific and cross-protective for other Orthopoxviruses
• Protective against heterologous JE virus genotypes
• Effective in preventing viral replication 1

Studies in mice have demonstrated that:

• Passive transfer of neutralizing antibodies protects against JE virus challenge
• There is a dose-response relationship between antibody titer and protection level
• Neutralizing antibody titers of ≥10 provide high levels of protection 1

Indications for Vaccination

The vaccine is recommended for:

1. Travelers to JE-endemic countries who plan to:

   • Stay ≥30 days during JE virus transmission season
   • Visit rural areas
   • Have uncertain itineraries or activities that might increase risk 1

2. Laboratory workers with potential exposure to JE virus 1

Administration Schedule

The recommended primary immunization series is:

• Three doses administered subcutaneously on days 0,7, and 30
• An abbreviated schedule of days 0,7, and 14 can be used when necessary
• The last dose should be administered at least 10 days before travel 1

For children 1-3 years of age, the dosage is 0.5 mL administered subcutaneously 1.

Efficacy and Duration of Protection

• After primary vaccination, >95% of recipients develop neutralizing antibodies 1
• Protective levels of neutralizing antibody persist for at least 2 years after completing a three-dose series 1
• Booster doses may be administered after 2 years, though the full duration of protection is unknown 1

Precautions and Contraindications

The vaccine should not be administered to:

• Persons with proven or suspected hypersensitivity to vaccine components
• Persons who have had previous adverse reactions to JE vaccine 1

Special considerations:

• No data available on safety and efficacy in infants less than 1 year of age
• Pregnancy: Theoretical risk to the developing fetus; should be administered only when risk of JE infection outweighs potential risks of vaccination 1

Common Pitfalls and Caveats

1. Timing of vaccination: Ensure vaccination is completed at least 10 days before travel to allow for adequate immune response and access to medical care in case of delayed adverse reactions 1.

2. Risk assessment: Many healthcare providers fail to properly assess travelers' risk for JE. In one study, 72% of higher-risk travelers were not administered JE vaccine, with providers incorrectly determining that the vaccine was not indicated in 55% of these cases 1.

3. Adverse reactions: Generalized urticaria and angioedema can occur within minutes to 2 weeks after vaccination. Patients should be:

   • Observed for 30 minutes after vaccination
   • Warned about delayed reactions
   • Advised to remain in areas with ready access to medical care for 10 days after vaccination 1

4. Confusion with other vaccines: Do not confuse JE vaccine with other travel vaccines such as yellow fever vaccine (YF-VAX) 1 or smallpox vaccine (Dryvax) 1, which have different indications, contraindications, and administration schedules.

Remember that proper risk assessment and timely administration are crucial for effective protection against Japanese encephalitis in travelers to endemic areas.