Thursday, March 29, 2018

New funding (and new hope) for a Lassa virus vaccine

Nearly 2 years ago in 2016, I wrote a post about a deadly virus that was causing a worrying outbreak in Nigeria: the Lassa virus. For the rest of 2016 and 2017, the outbreak lessened in severity, but it was not completely eliminated. Unfortunately, this year has featured a new surge in infections with the virus. In just the first 2 months of 2018, at least 317 people have been infected with Lassa virus, far surpassing the 143 cases confirmed in all of 2017. Additionally, around 20% of those infected in 2018 have died from the infection.

While the reports from March suggest that the current outbreak is slowing, major hurdles for the containment and management of Lassa fever cases still exist. The disease is carried by multimammate rats, which are difficult to keep out of homes and away from human food, especially as populations in Africa grow and the once-empty fields where the rodents live are developed. The long asymptomatic period at the beginning of infection makes it difficult to diagnose and treat effectively. Even once symptoms do manifest, they tend to be mild and non-specific, with 80% of those infected suffering from mild fever, general malaise, and/or headache. Additionally, the sub-optimal treatments have not improved in recent years, and there is still no vaccine.

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Lassa virus particles. CDC's Public Health Image Library.
Image # 8700; photo credit: C.S. Goldsmith.
In an attempt to deal with these issues, the Coalition for Epidemic Preparedness Innovations (CEPI) awarded $37.5 million to Themis Bioscience earlier this month for the development of their Lassa virus vaccine. CEPI was created in the wake of the Ebola epidemic and receives funding from the Wellcome Trust, the Bill & Melinda Gates Foundation, the European Commission, and the governments of Germany, Japan, Norway, Belgium, Canada, and Australia to support the development of vaccines for potential or existing pandemics. While there are many diseases that could fall into this category, the main focus in the next 5 years for the group will be Lassa virus, the Middle East Respiratory Syndrome (MERS) virus, and Nipah virus.

With the funding from CEPI, Themis plans to move into human trials with their Lassa virus vaccine as early as this year. Following the Ebola crisis, the World Health Organization developed a procedure to fast-track the approval of products for use in public health emergencies. The hope is that these procedures could be used in the context of the Lassa virus outbreak to accelerate the development of the Themis vaccine. To further speed development, the Themis Lassa virus vaccine will be based on the measles vaccine vector previously created by the Institut Pasteur, which has already been used effectively in humans. By inserting Lassa virus proteins into this vector, a new vaccine that will prime the body to respond to a Lassa infection will be created. This strategy opens the door to allow for the rapid creation of additional vaccines, as well.

The funding from CEPI will support the preclinical and initial clinical development through a phase 2 trial of the Themis Lassa virus vaccine in order to test its safety and efficacy. The ultimate goal is that the funds will allow the production of a vaccine stockpile that will be ready to test in an outbreak, which may be needed sooner rather than later. While the current outbreak appears to be slowing, and the dry season, when the majority of Lassa fever cases in Nigeria have historically occurred, is coming to an end, a report from Sierra Leone has suggested that the incidence of Lassa fever may actually be higher during the rainy season. This leaves uncertainty about the outlook for the current Lassa fever outbreak. But whether the outbreak continues now or goes dormant for the next 10 years, a vaccine will be a vital weapon in the fight against Lassa virus for the future.

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