Vaccine news: Chikungunya and Lassa fever
Chikungunya vaccine
Durham, North Carolina based, Bavarian Nordic announced today the U.S. commercial availability of VIMKUNYA™ (Chikungunya Vaccine, Recombinant), the first virus-like particle single-dose, pre-filled syringe chikungunya vaccine approved by the U.S. Food and Drug Administration (FDA) for use in individuals aged 12 and above.
VIMKUNYA™ addresses an important unmet public health need by expanding those eligible for vaccination against chikungunya to travelers aged 12 and over. Prior to approval, the only FDA approved vaccine for chikungunya prevention was indicated for travelers aged 18 and above.
VIMKUNYA™ is the first chikungunya vaccine to leverage VLP technology, which means it uses virus-like particles designed to mimic the chikungunya virus without the ability to infect cells, replicate or cause disease.
“The commercial availability of VIMKUNYA™ in the U.S. underscores our commitment to addressing emerging health threats and safeguarding communities nationwide,” said Lee Ann Kimak, Vice President, Commercial for North America at Bavarian Nordic. “As the first virus-like particle single-dose, pre-filled syringe chikungunya vaccine, VIMKUNYA™ provides a crucial new tool to help protect at-risk individuals traveling to regions where the virus is spreading.”
VIMKUNYA™, a single-dose 1-mL glass pre-filled syringe, was approved by the U.S. Food and Drug Administration (FDA) on February 14, 2025. The approval was based on results from two phase 3 clinical trials which enrolled more than 3,500 healthy individuals 12 years of age and older. Primary endpoints were met in the phase 3 trials, with results showing that 21 days after vaccination, VIMKUNYA™ induced neutralizing antibodies in up to 97.8% of individuals vaccinated and demonstrated a rapid immune response starting to develop within one week. The vaccine was well-tolerated and adverse events were mainly mild or moderate in nature.
Lassa fever
A National Institutes of Health (NIH)-sponsored clinical trial of a candidate vaccine to prevent Lassa fever has begun enrolling participants at the University of Maryland School of Medicine, Baltimore.
Currently, there are no specific drug treatments or vaccines for Lassa fever. NIH’s National Institute of Allergy and Infectious Diseases (NIAID) is sponsoring the Phase 1 trial.
“The candidate vaccine being tested in this trial was developed by an NIH-supported research team at Thomas Jefferson University in Philadelphia,” said NIAID Director Jeanne Marrazzo, M.D., M.P.H. “The progression of this candidate from the lab to a first-in-humans clinical trial is a promising step towards a vaccine to prevent Lassa fever.”
The trial will enroll up to 55 healthy adults between the ages of 18 and 50 years to test the safety and immunogenicity of three different concentrations of the vaccine candidate. Participants will receive two injections, delivered 28 days apart, of either the vaccine candidate or a Food and Drug Administration-licensed rabies vaccine (control).
In research published in 2024, Matthias Schnell, Ph.D., and colleagues at Thomas Jefferson University tested the experimental vaccine, known as LASSARAB, in nonhuman primates. They found that two doses of the vaccine, delivered 28 days apart, protected all the immunized animals that were exposed to large and lethal amounts of Lassa virus six weeks after the second inoculation.
LASSARAB is based on a weakened (attenuated) rabies vaccine that is subsequently inactivated to make the vaccine candidate. The experimental vaccine is then modified so that it expresses all the rabies proteins found in inactivated rabies vaccine along with a Lassa virus surface protein called the glycoprotein precursor complex (GPC). If LASSARAB is shown to be safe and elicits a good immune response to both the rabies proteins and the Lassa GPC, it could be used to prevent both diseases pending further testing in clinical trials and subsequent approval by the FDA.