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Lassa Fever Vaccine Candidates 2025

The U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have not approved vaccines for the Lassa fever virus (LASV). As of November 2025, four Lassa fever vaccine candidates (LASSARAB, INO-4500, MV-LASV, rVSV∆G-LASV-GPC, and EBS-LASV) have entered clinical trials.

Given its potential to cause a public health emergency of international concern, LASV is included in the World Health Organization (WHO) R&D Blueprint, a list of priority pathogens for which there is an urgent need for accelerated research, vaccine development, and countermeasures. The WHO has ranked Lassa (arenaviruses) as the most likely animal virus to spill over into humans ahead of Ebolavirus. A detailed estimate of the damage caused by LASV outbreaks, published in August 2024, has found that it infects 2.7 million people annually, ten times more than health agencies had previously assumed. Modelling research predicts that up to 600 million people could be at risk of Lassa fever infection by 2050, due to the combined effects of climate change and population growth.

The International AIDS Vaccine Initiative (IAVI) LASV vaccine candidate is conducting research (IAVI C105 and C102) to evaluate the Safety, Tolerability, and Immunogenicity of the rVSV∆G-LASV-GPC Vaccine in Adults and Children living in West Africa. As of 2025, Ghana, Liberia, and Nigeria are vaccinating volunteers. The Coalition for Epidemic Preparedness Innovations supported a Phase I (clinical trial IAVI C102). Batavia Biosciences manufactured the IAVI's LASV vaccine candidate in Leiden, the Netherlands.

rLASV/IGR-CD, developed by the Texas Biomedical Research Institute, The Scripps Research Institute, and the National Institute of Allergy and Infectious Diseases, incorporates both attenuation determinants and further enhances the vaccine's safety. Data published in November 2024 support the development of rLASV/IGR-CD as a live-attenuated LF vaccine with stringent safety features.

The Lassa fever vaccine candidate LASSARAB uses a deactivated rabies virus platform to deliver antigens to protect against the Lassa fever virus. Researchers from Thomas Jefferson University and the University of Maryland, Baltimore, have developed LASSARAB in collaboration with the United States Army Medical Research Institute of Infectious Diseases and the Geneva Foundation. The primary completion date of the Phase 1 study is 2026-03.

ChAdOx1-Lassa-GPC is a chimpanzee adenovirus-vectored vaccine candidate encoding the Josiah strain LASV glycoprotein precursor gene.

Themis Bioscience GmbH is a recombinant, live-attenuated, measles-vectored Lassa fever vaccine candidate (MV-LASV). In a first-in-human phase 1 trial, MV-LASV (V182-001) showed an acceptable safety and tolerability profile, and immunogenicity was unaffected by pre-existing immunity against the vector.

Inovio discontinued the development of product candidates targeting Lassa Fever (INO-4500) on November 17, 2022.

Lassa Fever Overview

Lassa fever (LF) is an acute viral hemorrhagic fever (VHF) caused by the Lassa virus. The natural reservoir for the LASV is the Mastomys natalensis rodent (African rat). Lassa virus is endemic in the West African countries of Benin, Ghana, Guinea, Liberia, Mali, Nigeria, and Sierra Leone. 

In epidemiological week 23 (June 2025), 146 new confirmed cases of Lassa fever, including one death, were reported from four states across Nigeria. During 2025, a cumulative total of 765 cases with 143 deaths (CFR 18.9 %) have been reported from 18 Nigerian states, mainly in Ondo, Bauchi, Edo, Taraba, and Ebonyi.

As of March 2025, Liberia has reported confirmed Lassa fever cases, with none in the latest update. Grand Bassa County remains the only area with active transmission of the disease. Since January 2022, the cumulative total stands at 186 confirmed cases, including 56 deaths (CFR 30%), with Bong, Nimba, and Lofa counties being the most affected historically.

Lassa Fever Vaccine News

December 16, 2024 – A vaccine candidate against the Lassa virus completely protected guinea pigs exposed to an otherwise lethal dose of the virus, reported researchers from Texas Biomedical Research Institute, The Scripps Research Institute, and The National Institute of Allergy and Infectious Diseases.

January 4, 2024 - Research findings defined a prefusion-stabilized GPC trimer, revealed an apex-situated site of vulnerability, and demonstrated that a cleavage-intermediate LASV trimer elicits LASV-neutralizing responses.

August 24, 2023 - Imunon, Inc. entered into a Cooperative Research and Development Agreement with the National Institute of Allergy and Infectious Diseases to evaluate the immunogenicity and efficacy of two IMUNON DNA-based Lassa vaccine candidates.

March 16, 023—The Lancet published a study that concluded that MV-LASV showed an acceptable frequency and tolerability and that immunogenicity seemed unaffected by pre-existing immunity against the vector. 

August 31, 022 – IAVI announced that volunteers at the PREVAIL clinical trial site at Redemption Hospital in Monrovia, Liberia, have been vaccinated with its novel vaccine candidate against LASV in a Phase 1 clinical trial.

Travel Diseases December 2025

Vaccine-preventable disease outbreaks, such as polio, yellow fever, Ebola, measles, cholera, and chikungunya, continue to disrupt international travel in 2025, says the U.S. Centers for Disease Control and Prevention (CDC). In the United States, the National Notifiable Diseases Surveillance System collects data on reportable diseases from various jurisdictions. As of December 2025, the CDC published Travel Health Advisories and digital maps indicating disease outbreaks in multiple countries.

The World Health Organization (WHO) and the UK Health Security Agency (UKHSA) emphasize the importance of checking your destination before travel and staying prepared by staying up to date with the latest outbreaks and events. The UKHSA published an analysis of travel-related diseases in the United Kingdom for the first half of 2025. The WHO and the Pan American Health Organization (PAHO) publish weekly Epidemiological Updates for mosquito-transmitted diseases in 2025. The WHO publishes global trends and total numbers in reported cases of selected vaccine-preventable diseases.

Travel Diseases

As of 2025, the U.S. Food and Drug Administration (FDA) has approved vaccines targeting travel-related diseases, such as the following:

Chagas Disease - Researchers from Texas A&M University, the University of Florida, and the Texas Department of State Health Services say the time is now to recognize Chagas disease as endemic in the U.S. As of 2025, no vaccines are available to prevent Chagas disease.

Chikungunya: Chikungunya is a viral disease transmitted to humans by mosquitoes infected with the Chikungunya virus (CHIKV). Outbreaks are primarily found in Africa, Asia, Brazil, and the Indian subcontinent. In 2023, the U.S. FDA approved a CHIKV preventive vaccine, nd in 2025, a second one, VIMKUNYA® 2025.

Cholera: The WHO has recorded seven cholera pandemics over the past two centuries, with the current (7th) cholera epidemic, which began in 1961, expected to continue in 45 countries by 2025. WHO-prequalified oral cholera vaccines (OCV), such as DUKORAL, are available. VaxChora® became available in the U.S. in late 2023.

Dengue: The dengue virus is transmitted to humans through the bite of infected mosquitoes. There are four Dengue serotypes, and any of them can infect you.

Ebola: Ebola virus disease is a rare but often fatal illness in humans. The Ervebo® vaccine was approved by the U.S. FDA in 2020. 

Hepatitis: Hepatitis is an inflammation of the liver. The five main strains of hepatitis viruses include hepatitis A, hepatitis B, hepatitis C, hepatitis D, and hepatitis E. The CDC updated hepatitis vaccination schedules for children, adolescents, and adults. 

Influenza: Various influenza viruses continually spread worldwide. Several FDA-approved flu shots are available in 2025.

Japanese Encephalitis (JE) is a severe virus that spreads to people through the bites of infected mosquitoes. FDA-approved JE vaccines are available in the U.S.

Lassa Fever is an acute viral infection that originates and spreads through contact with a typical African rodent, such as the multimammate rat. As of 2023, the U.S. FDA has not approved a Lassa fever vaccine.

Lyme disease is a Tickborne disease common in Europe and the United States, transmitted to humans through the bite of infected ticks. No vaccine has been approved in 2025.

Malaria: A life-threatening disease caused by parasites transmitted to people through the bites of infected female Anopheles mosquitoes. It is preventable with the Mosquirix and R21/Matrix-M malaria vaccines, which are available in Africa, not the U.S.

Marburg: Marburg virus disease (MVD) is a severe human disease caused by the Marburg virus. Recent outbreaks in Africa have caused MVD. As of 2025, the FDA has not approved a vaccine for MVD.

Measles: Highly contagious, severe viral Disease; vaccines (MMR-II and Priorix) are available throughout the U.S., but the Disease poses a risk to international travelers visiting countries such as India.

Meningococcal: Vaccines can help prevent meningococcal Disease, which is any illness caused by the bacterium Neisseria meningitidis.

MERS: Middle East Respiratory Syndrome vaccines are not approved in 2025, but several vaccine candidates are being tested in clinical trials.

Mpox: Mpox is caused by the mpox virus, and outbreaks began in May 2022 and continue in 2023. Authorized vaccines such as JYNNEOS® are available in various countries in 2023.

Oropouche is a known disease that is emerging in parts of South America, Central America, and the Caribbean. As of July 2025, a commercial test was announced. Reverse transcription PCR testing can identify the RNA of the virus during the early stages of infection, aiding in diagnosis. Serology testing, which identifies antibodies produced by the immune system in response to the virus, can assist in diagnosing the virus in later stages of infection.

Polio is a highly infectious disease caused by the poliovirus. There is no cure for polio, but vaccines can prevent it. Canada, Israel, Germany, the UK, New York, Spain, and various African and European countries have detected the rabies virus in wastewater and in expanded vaccination programs. Rabies is a vaccine-preventable viral disease in over 150 countries and territories. It is present on all continents except Antarctica, with over 95% of human deaths occurring in the Asia and African regions. It is spread to people and animals through bites or scratches, usually via saliva. Dogs are responsible for up to 99% of rabies transmission to humans. 

Rift Valley Fever: An epidemic in Africa that can be fatal to humans. As of 2023, no vaccines are available for human use. However, the ThVF vaccine candidate was found safe, well-tolerated, and immunogenic when administered as a single dose in this University of Oxford phase 1 study population.

Rotavirus: Four rotavirus strains are WHO prequalified.

Tickborne encephalitis: The Tickborne encephalitis virus belongs to the family Flaviviridae. Four FDA-approved vaccines are currently available.

Typhoid: Typhoid fever is a life-threatening infection caused by Salmonella Typhi. It is usually spread through contaminated food or water. One FDA-approved vaccine has been used for many years to prevent typhoid.

Tuberculosis (TB) is a potentially severe infectious disease that primarily affects the lungs. The Bacillus Calmette-Guérin (BCG) vaccine helps prevent TB. 

West Nile Virus: Phoenix, Arizona, has become a West Nile Virus (WNV) hot spot in the U.S. in 2023. However, the U.S. FDA has not authorized a WNV vaccine for prevention.

Yellow Fever: Yellow fever is an acute viral hemorrhagic disease transmitted by infected mosquitoes. A small proportion of patients who contract the virus develop severe symptoms, and approximately half die within 7 to 10 days. Yellow fever vaccines (YF-Vax® and Stamaril®) are available worldwide.

Zika: Zika virus outbreaks in Brazil, India, and Puretro Rico are expected to continue in 2025. However, as of July 2025, no approved Zika vaccines are available.

Travel Vaccine Appointments

Request a pre-departure travel vaccination advisory appointment with a healthcare professional using this weblink.