West Nile Virus 2023

West Nile Virus May 2023

Since 1999, West Nile Virus (WNV) has become the leading cause of arthropod-borne viral (arboviral) disease in the United States, says the U.S. Centers for Disease Control and Prevention (CDC). As of January 10, 2023, a total of 1,035 cases of WNV disease in people have been reported to CDC, led by Colorado (204) and California (168). And in Maricopa County, (Phoneix) Arizona, 1,487 cases were reported, 68% were hospitalized, and 7% were related deaths in 2021, compared to only 3 WNV cases in 2020. Of these, 737 (71%) were classified as neuroinvasive diseases, such as meningitis or encephalitis.

Our experience over the past two decades has demonstrated that current prevention strategies are not enough to reduce the ongoing WNV disease burden. WNV vaccination would be more effective in preventing WNV disease and related deaths, wrote a Perspective published by the NEJM on May 4, 2023. In addition, lessons from developing other vaccines can be applied to move WNV vaccine candidates further through development to ensure the availability of safe and effective vaccines for people at risk.

West Nile Virus Vaccine Candidates

As of May 4, 2023, there are no U.S. FDA-approved WBV vaccines. However, active clinical studies include several vaccine candidates, including two live attenuated chimeric, one DNA, one recombinant subunit, and two inactivated whole-virus vaccines.

In phase 2 trials, the live attenuated recombinant yellow fever vaccine strain expressing the premembrane and envelope (prM–E) genes of WNV (ChimeriVax-WN02, Sanofi Pasteur) was found to have a good safety profile and immunogenicity even in older age groups after a single dose.

The HydroVax-001 vaccine candidate consists of a hydrogen peroxide inactivated whole virion (WNV-Kunjin strain) adjuvanted with aluminum hydroxide.