Merck Responds to Sudan Ebolavirus Outbreak in Uganda with Plans to Produce and Donate Investigational Vaccine Doses for IAVI’s Vaccine Development Program


October 25, 2022 7:00 am ET

RAHWAY, N.J., Oct. 25, 2022 – Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced today that in response to the health and humanitarian crisis of the Sudan ebolavirus outbreak in Uganda, the company plans to produce and donate vials of investigational candidate Sudan ebolavirus vaccine to IAVI, a global nonprofit scientific research organization, for further clinical research use. IAVI plans to use these vials for its ongoing Sudan ebolavirus vaccine development program. The vials will be produced from existing investigational bulk drug substance previously manufactured by Merck and are intended to be used as part of the World Health Organization’s (WHO’s) efforts to fight the outbreak in Uganda. Merck and IAVI are working toward a formal agreement and are collaborating now to accelerate this effort.

“We are proud to work together with IAVI in support of the World Health Organization’s response to address the Sudan Ebola outbreak in Uganda,” said Beth-Ann Coller, executive director, Global Clinical Development Vaccines, Merck Research Laboratories. “We are moving with urgency to prepare these vials and donate them to IAVI as quickly as possible to help support the efforts of the WHO and the people of Uganda as they grapple with this outbreak.”

Merck anticipates that it will fill approximately 50,000 doses for IAVI from the existing bulk drug substance by the end of 2022. Further use in the response to the outbreak will be subject to authorization by applicable health authorities.

Dr. Mark Feinberg, president and CEO of IAVI, said, “We are very grateful to Merck for supplying the investigational vaccine for IAVI, which will help accelerate IAVI’s program. IAVI looks forward to working with partners responding to the ongoing Sudan Ebola outbreak to evaluate vaccine effectiveness and safety. We hope that our efforts may contribute to the response in Uganda should the outbreak persist, and also enable the world to be better prepared for future Sudan Ebola outbreaks.”

The vials of investigational Sudan ebolavirus vaccine to be donated by Merck use a replication-competent, live, attenuated recombinant vesicular stomatitis virus (rVSV) vaccine construct similar to that used for ERVEBO® (Ebola Zaire Vaccine, Live), the company’s vaccine approved for the prevention of disease caused by Zaire ebolavirus in individuals 18 years and older as a single dose administration. Over the past 20 years, Zaire ebolavirus has been the most common cause of Ebola outbreaks. ERVEBO does not protect against other species of Ebolavirus, including the Sudan ebolavirus.

About ERVEBO® (Ebola Zaire Vaccine, Live)

ERVEBO was initially engineered by scientists from the Public Health Agency of Canada’s National Microbiology Laboratory and the technology was subsequently licensed by a subsidiary of NewLink Genetics Corporation now known as Lumos Pharma, Inc. ERVEBO is approved in the European Union, United Kingdom, United States, Switzerland, and 10 countries in Africa.

In the United States, ERVEBO is a vaccine indicated for the prevention of disease caused by Zaire ebolavirus in individuals 18 years of age and older. The duration of protection conferred by ERVEBO is unknown. ERVEBO does not protect against other species of Ebolavirus or Marburgvirus. Effectiveness of the vaccine when administered concurrently with antiviral medication, immune globulin (IG), and/or blood or plasma transfusions is unknown.

Selected Safety Information for ERVEBO


Management of Acute Allergic Reactions

Among 15,399 subjects vaccinated with ERVEBO, there were two reports of anaphylaxis. Monitor individuals for signs and symptoms of hypersensitivity reactions following vaccination with ERVEBO. Appropriate medical treatment and supervision must be available in case of an anaphylactic event following the administration of ERVEBO.

Limitations of Vaccine Effectiveness

Vaccination with ERVEBO may not protect all individuals. Vaccinated individuals should continue to adhere to infection control practices to prevent Zaire ebolavirus infection and transmission.

Immunocompromised Individuals

The safety and effectiveness of ERVEBO have not been assessed in immunocompromised individuals. The effectiveness of ERVEBO in immunocompromised individuals may be diminished. The risk of vaccination with ERVEBO, a live virus vaccine, in immunocompromised individuals should be weighed against the risk of disease due to Zaire ebolavirus.


Vaccine virus RNA has been detected by RT-PCR in blood, saliva, urine, and fluid from skin vesicles of vaccinated adults. Transmission of vaccine virus is a theoretical possibility.


The most common injection-site adverse reactions reported by subjects taking ERVEBO in Study 1 (N=500) were injection-site pain (34.0%) and redness/swelling (2%).  The most common systemic adverse reactions reported following vaccination with ERVEBO in Study 1 (N=498) were headache (37%), feverishness (34%), muscle pain (33%), fatigue (19%), nausea (8%), joint pain/tenderness (7%), rash (4%), and abnormal sweating (3%).  Study 1 was conducted in Liberia (N=1,000). Subjects were randomized 1:1 to receive ERVEBO or saline placebo and were assessed at Week 1 and Month 1 postvaccination for solicited local and systemic reactions. In a subset of subjects (n=201), joint symptoms and signs were also solicited during a Week 2 visit.

The most common injection-site adverse reactions reported by subjects taking ERVEBO in Study 2 (N=1051) were injection-site pain (70.0%), swelling (17%), and redness (12%).  The most common systemic adverse reactions reported following vaccination with ERVEBO in Study 2 (N=1051) were joint pain (18%), arthritis (5%), rash (4%), and vesicular lesions (2%).  Study 2 was conducted in the United States, Canada, and Spain (N=1,197). Subjects were randomized to receive ERVEBO (n=1,061) or saline placebo (n=133). Subjects recorded solicited local reactions from Days 1 to 5 postvaccination, and daily temperature measurements and solicited joint and skin events from Days 1 to 42 postvaccination.


Interference with Laboratory Tests

Following vaccination with ERVEBO, individuals may test positive for anti-Ebola glycoprotein (GP) antibody and/or Ebola GP nucleic acid or antigens. GP-based testing may have limited diagnostic value during the period of vaccine viremia, in the presence of vaccine-derived Ebola GP, and following antibody response to the vaccine.


There are no adequate and well-controlled studies of ERVEBO in pregnant women, and human data available from clinical trials with ERVEBO are insufficient to establish the presence or absence of vaccine-associated risk during pregnancy.

Human data are not available to assess the impact of ERVEBO on milk production, its presence in breast milk, or its effects on the breastfed child.

About Merck

At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit and connect with us on TwitterFacebookInstagramYouTube and LinkedIn.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

This news release of Merck & Co., Inc., Rahway, N.J., USA (the “company”) includes “forward-looking statements” within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. These statements are based upon the current beliefs and expectations of the company’s management and are subject to significant risks and uncertainties. There can be no guarantees with respect to pipeline candidates that the candidates will receive the necessary regulatory approvals or that they will prove to be commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual results may differ materially from those set forth in the forward-looking statements.

Risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of the global outbreak of novel coronavirus disease (COVID-19); the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of the company’s patents and other protections for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory actions.

The company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in the company’s Annual Report on Form 10-K for the year ended December 31, 2021 and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (

Before administering ERVEBO® (Ebola Zaire Vaccine, Live), please read the Prescribing Information at  The Patient Information is also available at

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