Amid outbreaks, Marburg vaccine shows promise in human trial
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An experimental vaccine against Marburg virus showed promise in a first-in-human phase 1 trial and could one day be used to stop outbreaks of the disease, the NIH said.
Data from the trial were published recently in The Lancet, in between outbreaks of Marburg virus in Ghana and Equatorial Guinea.
Three people were infected in the Ghana outbreak, which was declared over in September. Two died.
A larger outbreak appears to be occurring in Equatorial Guinea, which confirmed its first outbreak of the disease on Monday. According to WHO, out of eight samples sent from the country’s Kie Ntem Province, one has tested positive for Marburg virus, but there have been nine deaths and 16 suspected cases reported overall.
WHO said it has deployed experts, personal protective equipment and other supplies for the emergency response.
“Marburg is highly infectious,” Matshidiso R. Moeti, MD, MPH, WHO regional director for Africa, said in the release. “Thanks to the rapid and decisive action by the Equatorial Guinean authorities in confirming the disease, emergency response can get to full steam quickly so that we save lives and halt the virus as soon as possible.”
Illness caused by Marburg virus, which is in the same family as the virus that causes Ebola, begins “abruptly,” with many patients developing hemorrhagic symptoms within about a week, according to WHO.
Patients may receive supportive care, including rehydration with oral or IV fluids and treatment of specific symptoms, but there are no approved Marburg virus vaccines or treatments and the disease has a fatality rate as high as 88%, WHO noted.
A range of potential blood products, immune therapies and vaccines are in development, including the cAd3-Marburg vaccine, which was developed by the National Institute of Allergy and Infectious Diseases and tested in a phase 1, first-in-human trial.
In the open label, dose-escalation trial, the vaccine elicited a robust antibody response in 95% of participants, including 70% who maintained the immune response for more than 48 weeks, according the published results.
“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,” researchers wrote in the study.
For the study, the researchers enrolled 40 healthy adults at the Walter Reed Army Institute of Research Clinical Trials Center between Oct. 9, 2018, and Jan. 31, 2019, with 20 receiving a single intramuscular dose of the cAd3-Marburg vaccine at 1 x 1010 particle units (pu) and the other 20 receiving a single vaccine dose at 1 x 1011 pu.
The vaccine was judged to be safe, well tolerated and immunogenic, with no serious adverse health events related to vaccination. Of the 40 participants, 37 (93%) completed follow-up visits, two moved from the area and one was lost to follow-up.
The most common side effects were pain and tenderness at the injection site (68%), malaise (45%), headache (43%) and myalgia (35%).
Thirty-eight of 40 participants (95%) had glycoprotein-specific antibodies 4 weeks after vaccination, which remained high 48 weeks later.
The results are promising because several experimental vaccines have been tested in the past but none effectively offered long-term protection, experts said.
“In areas of Africa where a vaccine for Marburg is most needed, a single-dose vaccine that could protect recipients over a long period of time would be a crucial part of quelling outbreaks,” the NIH said in a press release.
Future trials of the cAd3-Marburg vaccine are planned for Ghana, Kenya, Uganda and the United States, the agency said.
References:
- Hamer M, et al. Lancet. 2023;doi:10.1016/S0140-6738(22)02400-X
- Marburg vaccine shows promising results in first-in-human study. https://www.nih.gov/news-events/news-releases/marburg-vaccine-shows-promising-results-first-human-study. Published Jan. 30, 2023. Accessed Feb. 14, 2023.
- WHO. Equatorial Guinea confirms first-ever Marburg virus disease outbreak. Published Feb. 13, 2023. Feb. 14, 2023.
- WHO. Marburg virus – Ghana. https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON409. Published Sept. 26, 2022. Accessed Feb. 14, 2023.
Perspective
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Tracey Goldstein, PhD
The phase 1 trial for a Marburg vaccine is extremely promising. If approved and effectively deployed, this new vaccine will play a critical role in responding to future Marburg outbreaks, which we know are likely to occur across a wider geographical area than previously understood.
In 2017, the U.S. Agency for International Development (USAID) helped detect Marburg virus in bats in Sierra Leone — a first for West Africa. This information has helped neighboring countries to be better prepared to recognize and test for Marburg. As a result, in 2021, Guinea was able to quickly detect and confirm its first-ever human case of Marburg hemorrhagic fever. No additional cases were detected, and the outbreak was declared over 1 month later.
If approved, USAID looks forward to working with partners and communities to effectively and equitably distribute the vaccine when responding to future Marburg outbreaks.
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