The Vero cell-derived, inactivated, SA₁₄-14-2 strain-based vaccine (Ixiaro) for prevention of Japanese encephalitis

Abstract

With an estimated 68,000 cases each year, Japanese encephalitis (JE) is the leading cause of viral encephalitis in Asia. Vaccination against the disease is recommended for endemic populations and also for travelers at risk. Recently, a Vero cell-derived, inactivated, SA₁₄-14-2 strain-based JE vaccine (JE-VC) became available for travelers from non-endemic regions, replacing the traditional mouse brain-derived vaccines. First licensed in 2009, JE-VC is currently available in Europe, the USA, Canada, Australia and several other countries. In 2013, the vaccine was approved by the European Medicines Agency and the US Food and Drug Administration for use in children. This review summarizes current data on the immunogenicity, safety and clinical use of JE-VC.

Keywords:

• immunogenicity
• Ixiaro
• Japanese encephalitis
• JE-VC
• Japanese encephalitis vaccine
• safety
• traveler

Financial & competing interests disclosure

The preparation of this review was supported financially by the Finnish Society of Infectious Diseases Specialists. One of the studies conducted by the authors EO Erra, A Kantele and co-workers was supported in part by Novartis Vaccines and Diagnostics (assay expenses). A Kantele has been a member of the advisory boards of Novartis (Boston, 2011) and Crucell (Stockholm, 2013) and has received honoraria from these organizations. A Kantele has received travel grants for travel to medical conferences from Crucell, Janssen and GSK; has acted as a consultant of vaccination immunology for Crucell in 2010; has lectured for Baxter, Crucell, GSK and Pfizer and has received an investigator-initiated grant from Crucell in 2010 and from Pfizer in 2012. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Key issues

• JE-VC is a Vero cell-derived, inactivated, SA₁₄-14-2 strain-based, alum-adjuvanted vaccine for the prevention of Japanese encephalitis.

• Since 2009, JE-VC has been licensed in Europe, the USA, Canada, Australia and several other countries.

• In 2013, the vaccine was also approved for use in children aged 2 months and older (by the EMA and FDA).

• The two-dose primary series induces a cross-reactive neutralizing antibody response against different Japanese encephalitis virus strains and genotypes.

• For adults, the first booster dose is currently recommended 12–24 months after the primary series.

• A single JE-VC dose efficiently boosts immunity in those previously primed with the traditional mouse brain-derived vaccines.

• JE-VC appears well-tolerated, with no alarming safety concerns detected.