A study in The Lancet with NIH funding reported that a vaccine candidate against Marburg virus (MARV) was safe and induced and immune response in a limited, first-in-human trial. Developed by researchers at NIAID, this experimental vaccine “could someday be an important tool to respond to Marburg virus outbreaks”.
MARV
MARV is a filovirus from the same family as Ebola. It causes a “rapidly progressive febrile illness” with a high mortality rate. The symptoms are similar to those caused by Ebola, including fever, chills, vomiting, and diarrhoea.
There are no approved vaccines or specific therapies beyond supportive care. Although some experimental vaccines have undergone testing in the past, none have demonstrated a sufficient level of efficacy and protection.
The trial
The first-in-human, Phase I trial took place at the Walter Reed Army Institute of Research Clinical Trials Centre in the USA. It was an open-label, dose-escalation trial, involving healthy adults aged 18-50 years old. The vaccine is a “replication-deficient recombinant chimpanzee adenovirus type 3 (cAd3)-vectored vaccine encoding a wild-type Marburg virus Angola glycoprotein”.
Primary safety endpoints included reactogenicity assessed for the first 7 days. Secondary immunogenicity endpoints were “assessment of binding antibody responses and T-cell responses” and “assessment of neutralising antibody responses” 4 weeks after vaccination.
Between October 2018 and January 2019, 40 healthy adults were enrolled in a dose-escalation plan. 4 weeks after vaccination glycoprotein-specific antibodies were induced in 38 of the 40.
Encouraging results
NIH reports the safety results as “encouraging”, noting “no serious adverse effects” from a vaccine that was “well-tolerated”. Furthermore, the vaccine “appeared to induce strong, long-lasting immunity to the MARV glycoprotein”.
Trials are now expected to take place in Ghana, Kenya, Uganda, and the US, with the hope of using the vaccine in emergency responses to outbreaks in the future.
“These findings represent a crucial step in the development of a vaccine for emergency deployment against a re-emerging pathogen that has recently expanded its reach to new regions.”
For more on the development of experimental vaccines against viruses like Marburg, come to the World Vaccine Congress in Washington 2023.
