Ebola is a disease that grabs headlines even though it is not typical in the U.S. The severe bleeding (called hemorrhagic bleeding), contagiousness of the infection, and the effects on infants when their mothers are infected during pregnancy cause fear and concern when media reports of an outbreak appear.

Ebola is caused by Ebola virus. Outbreaks usually occur in Africa. U.S. citizens with Ebola have been transported to the U.S. for care if infected while abroad. The first U.S. vaccine against Ebola virus was approved in 2019. The Ebola vaccine is not recommended for everyone because of the low risk for this infection among most people in the U.S. Two groups of people in the U.S. are recommended to get the Ebola vaccine. This includes those likely to be exposed to the virus by treating or transporting patients with Ebola and those doing research on the virus. Notably, even with vaccination available, Ebola virus research can only be completed in specialized facilities, known as high-containment facilities, to prevent inadvertent spread of the virus. 

The disease

What is Ebola and how do you catch it?

Ebola is a disease caused by Ebola virus. Most cases occur in Africa when people interact with infected wild animals. The virus spreads from person to person through direct contact with body fluids of an infected or deceased person, including blood, urine, saliva, feces, vomit, semen, amniotic fluid and breast milk. People can also be exposed through close contact with an infected person, likely from exposure to their respiratory secretions, or from exposure to objects contaminated with the virus, like clothing, bedding or needles. Some people have also been exposed through semen of people who recently recovered from Ebola.

People with Ebola typically begin showing symptoms about 8 to 10 days after exposure, but this timing can be as short as two days and as long as 21 days. The disease usually starts with “flu-like” symptoms, like fever and fatigue. People may also experience nausea, abdominal pain, diarrhea, and vomiting as well as a rash. Ebola virus damages blood vessels and causes problems with clotting of blood. Because of this, people can have signs of unusual internal or external bleeding. Examples can include unusual bruising; bleeding from the eyes, gums, nose or vagina; excess bleeding around injection sites or other breaks in the skin; and having blood in vomit or feces. Patients may also experience problems with the functioning of the heart, shock resulting from bloodstream infection, or confusion or aggression resulting from effects on the nervous system. 

Death rates from Ebola vary. While the average death rate is estimated to be about 50 of every 100 people with symptoms, death rates during outbreaks have ranged from 36 to 90 of 100 people with symptoms. 

The vaccine

The Ebola vaccine protects against disease caused by Ebola virus. 

How is the Ebola vaccine made?

People are protected against Ebola virus infection by making an immune response to a protein that sits on the surface of the virus. The Ebola vaccine is made by taking the part of the virus that makes surface protein ("surface protein gene") and putting it into a virus that does not cause disease in people. This “vector”, or carrier, virus is called vesicular stomatitis virus (VSV). Live, weakened VSV virus that includes the gene for the Ebola virus surface protein is used as the vaccine. 

How does the Ebola vaccine work?

The Ebola vaccine is a live, weakened viral vaccine that includes VSV virus containing the gene for the Ebola virus surface protein. As the vaccine virus reproduces, it makes the Ebola virus protein too, causing our immune system to make a protective immune response without causing Ebola disease.

Does the Ebola vaccine have side effects?

The Ebola vaccine can cause mild side effects, such as pain or soreness where the shot was given. A small number of people will also have a headache, fever, joint or muscle pain, or fatigue. Small numbers of people also experience other side effects, including:

• Nausea (about 8 in 100 people)
• Arthritis or swelling of the joints (about 5 in 100 people)
• Rash (about 4 in 100 people)
• Excessive sweating (about 3 in 100 people) 

These side effects typically last for less than a week. 

Other questions you might have

I have heard there is more than one type of Ebola virus. Is that correct? 

Yes. Four types of Ebola virus are known to cause disease in people:

• Zaire ebolavirus — This type is commonly referred to as Ebola virus. It is the most common cause of Ebola outbreaks. It is also the deadliest of the types.
• Sudan ebolavirus — This type is commonly referred to as Sudan virus. It is the second most common cause of Ebola outbreaks and the second most deadly type.
• Bundibugyo ebolavirus — This type is commonly referred to as Bundibugyo virus. It is the most recently discovered type of Ebola virus. To date, Bundibugyo virus has only caused two Ebola outbreaks.  
• Tai Forest ebolavirus — This type has only been known to infect a single person. That case occurred in 1994.

Does the Ebola vaccine protect against all four types of Ebola virus known to cause disease in people?

No. The vaccine approved for use in the U.S. protects against Zaire ebolavirus. It has not been shown to protect against disease caused by the other types of Ebola virus. Vaccines targeting other types of Ebola virus are in development, and some have been approved for use in other countries. 

Relative risks and benefits

Do the benefits of Ebola vaccine outweigh the risks?

Ebola is a devastating disease that can be fatal or cause lasting damage in those who survive. Fortunately, Ebola is rare, and outbreaks have never occurred in the U.S. Typically, cases of Ebola in the U.S. are isolated to people who have been caring for patients infected with the virus in outbreak settings in other countries. Scientists studying the virus are also at risk of exposure to the virus. Therefore, even though this vaccine is safe, most people would not benefit from getting it. This is why the vaccine is only recommended for a limited group of people in the U.S.

Disease risks

• Fever, nausea, vomiting, diarrhea
• Difficulty clotting blood, bleeding from eyes, nose, gums, vagina, and breaks in the skin
• Problems with functioning of the heart
• Shock resulting from bloodstream infection
• Lasting headache, fatigue, muscle and joint pain as well as memory loss
• Damage to eyes
• Can be fatal

Vaccine risks

• Pain, redness, and swelling at the injection site
• Mild fever
• Nausea (about 8 in 100 people)
• Arthritis (about 5 in 100 people)
• Rash (about 4 in 100 people)
• Excessive sweating (about 3 in 100 people) 

Reference

• Orenstein WA, Offit PA, Edwards KM and Plotkin SA. Ebola Vaccines in Plotkin's Vaccines, 8th Edition. 2024, 311-329.

Reviewed by Paul A. Offit, MD, on June 12, 2025