Priority diseases

Vaccines can help prevent disease outbreaks from becoming humanitarian crises. CEPI supports the development of vaccines and platform technologies against deadly diseases for which no licensed vaccines are currently available.

Targeting diseases with epidemic potential

Since our launch in 2017, CEPI has announced a number of funding calls to develop specific vaccine candidates or to fund research that can directly support development of vaccines against our priority pathogens.


CEPI has initiated 9 partnerships to develop vaccines against COVID-19. The programs will leverage rapid response platforms already supported by CEPI as well as new partnerships. The aim is to advance COVID-19 vaccine candidates into clinical testing as quickly as possible.


Before the emergence of COVID-19, CEPI’s priority diseases included Lassa virus, Middle East Respiratory Syndrome coronavirus, Nipah virus, Rift Valley Fever virus and Chikungunya virus. CEPI also invested in platform technologies that can be used for rapid vaccine and immunoprophylactic development against unknown pathogens (Disease X).


MERS-CoVLassaNipahDisease XRift Valley feverChikungunya
Disease X
Rift Valley fever

Middle East Respiratory Syndrome Coronavirus (MERS-CoV)


What is it?

MERS-CoV is the virus that causes Middle East respiratory syndrome (MERS). It is a coronavirus, part of the same family of viruses that causes the common cold and SARS (severe acute respiratory syndrome). MERS is a zoonotic disease, meaning it passes from animals to humans. It’s thought that camels are a major source of infection in people (known as primary cases). Raising camels, eating undercooked camel meat, and drinking raw camel milk or urine are risk factors for the disease in humans. MERS-CoV can also spread from person to person, usually through close contact (known as secondary cases).


Where does it occur?

The disease was first reported in Saudi Arabia in 2012, and most reported cases have been linked to countries in and around the Arabian Peninsula.


According to WHO, at the end of January 2020, a total of 2519 laboratory-confirmed cases of MERS, including 866 associated deaths (case-fatality rate: 34.3%) were reported globally.


The majority of these cases were reported from Saudi Arabia (2121 cases), including 788 related deaths with a case-fatality rate of 37.1%.


In 2015, a large outbreak occurred in South Korea as a result of a single super-spreading event, transmitting the virus to 82 people in three days.


Since 2012, cases have been reported in 27 countries. 12 countries in the Eastern Mediterranean region have reported cases.


Who does it affect?

MERS-CoV can infect people of any age. It causes a severe acute respiratory illness with fever, cough and shortness of breath. Gastrointestinal symptoms can also occur. Around 35-37% of people reported as having MERS have died, many of whom already had an underlying medical condition.


The age group 50–59 years continues to be at highest risk for acquiring infection of primary cases. The age group 30–39 years is most at risk for secondary cases. The number of deaths is higher in the age group 50-59 years for primary cases and 70-79 years for secondary cases.


How do we currently prevent infections?

People are advised to try and prevent getting infected by avoiding undercooked or raw camel products, and by being hygienic, especially around animals.


There is currently no specific antiviral treatment for or vaccine against MERS-CoV.


CEPI has 5 MERS vaccine candidates in its portfolio.

Lassa virus

What is it?

Lassa virus belongs to the Arenaviridae family and causes Lassa fever, also known as Lassa haemorrhagic fever (LHF). It is a haemorrhagic illness that occurs between one and three weeks after infection.


Lassa fever is a zoonotic disease, meaning it passes from animals to humans. The natural host of Lassa virus is the rodent Mastomys natalensis, otherwise known as the Natal multimammate mouse or rat.


The virus is spread when a person comes into contact with items contaminated with the rodent’s urine or faeces – for example, by handling objects, eating, or through open wounds. It can also be inhaled.


Lassa virus can pass from person to person via bodily fluids, and can spread in healthcare settings if suitable precautions are not taken.


Where does it occur?

Lassa virus was identified in 1969 after the death of two missionary nuns in Nigeria. Lassa fever occurs regularly in parts of West Africa, including, Sierra Leone, Nigeria, Guinea, Liberia, Mali Benin and Ghana. It is estimated to cause more than 300,000 cases of illness and 3000 deaths each year.


In 2018, Nigeria experienced an unusually large increase in Lassa fever cases which led the WHO to declare it an outbreak. A study identified that the spread of disease during this outbreak was largely a result of ongoing cross-species transmission from local rodent populations, rather than via human-human transmission.


Since the start of 2020, a total of 4761 suspected cases have been reported in Nigeria. Of these, 1006 were confirmed positive. Since the onset of the 2020 outbreak within the country, there have been 194 deaths in confirmed cases (giving a case-fatality ratio in confirmed cases at 19.3%).


The Lassa fever outbreak emergency phase was declared over on the 28 April 2020.


National Lassa fever multi-partner, multi-sectoral Technical Working Group (TWG) continue to coordinate response activities at all levels.


What does it do?

Around 80 per cent of patients with Lassa fever have no symptoms. Those that do can experience mild fever or headache. More serious symptoms include: vomiting, swelling of the face, pain in the chest, back and abdomen, and bleeding from body parts, including the eyes and nose.


Patients can be given rehydration therapy and supportive care. An antiviral drug ribavirin has been used successfully in some cases.


On average, one per cent of infections are fatal, usually within two weeks of symptoms beginning. However, in the current outbreak in Nigeria, the case fatality rate has remained around 20 per cent. Around 15 to 20 per cent of people hospitalised with Lassa fever die from it. A common complication in survivors of Lassa fever is hearing loss.


How do we currently prevent infections?

People are advised to avoid contact with Mastomys rodents, including by keeping homes clean and storing food away from rodents. Healthcare workers should follow specific infection control methods.


There is currently no vaccine against Lassa virus.


CEPI has 6 Lassa vaccine candidates in its portfolio.

Nipah virus

What is it?

Nipah virus belongs to the Paramyxoviridae family of viruses, genus Henipavirus, alongside Hendra virus. Nipah is a zoonotic disease, meaning it passes from animals to humans.


The natural hosts of the virus are fruit bats (also known as flying foxes) of the genus Pteropus. Nipah virus can be spread to people from infected bats, infected pigs, or infected people.


Where does it occur?

Nipah virus was first identified in 1999 during an outbreak of illness affecting pig farmers and others having close contact with pigs in Malaysia and Singapore. Over 100 human deaths were reported, and over a million pigs were killed in the effort to stop the outbreak. No cases of person-to-person spread were reported. In 2001, there was an outbreak of Nipah virus in people in Bangladesh, and a separate outbreak in a hospital in India. In both countries, person-to-person transmission occurred. Since then, Bangladesh has suffered outbreaks nearly every year – with over 300 confirmed cases occurring there from 2001 to 2015.


India has also occasionally reported cases and experienced an outbreak in the southern State of Kerala earlier in 2018. A total of 19 Nipah virus cases, including 17 deaths, were reported from Kerala State. Those who died included a nurse who had been caring for a patient ill with Nipah virus disease. More than 2500 contacts of Nipah patients were monitored by the state surveillance system and a 24-hour helpline took queries from the community. By mid-June, the Kerala government and the Union Health Ministry announced that the outbreak had been contained.


In June 2019, the Indian Government confirmed a new case of Nipah virus infection in a 23-year-old man in Kerala, India – the same state that experienced a deadly outbreak of the disease last year. The patient was hospitalised and was discharged after 2 months. In total, 355 case contacts were monitored and 7 were kept in the isolation ward of a government hospital.


So far, Nipah outbreaks have been confined to South and Southeast Asia, but Pteropus bats are found in a large geographical area across the globe covering a population of more than 2 billion people. A spread of the virus among these bat populations could put a huge number of people worldwide at risk of zoonotic infection. Furthermore, as the virus is capable of person-to-person spread, in theory a Nipah-infected individual could bring the virus even to regions where Pteropus bats do not live and infect others in those regions. Thus, Nipah virus has the biological potential to be a truly global threat.


What does it do?

Nipah virus infection can cause severe, rapidly progressive illness that affects the respiratory system and the central nervous system, including inflammation of the brain (encephalitis). Symptoms begin between 5 and 14 days after infection, and include fever, altered mental state, cough and respiratory problems.


Through a 14-year study in Bangladesh, another country prone to Nipah outbreaks, research published in May 2019 identified that increasing age and respiratory problems were key indicators in the infectivity of the virus.

How do we currently prevent infections?

People are advised to avoid contact with ill pigs and bats in countries where Nipah virus is known to occur. They are also advised to avoid drinking raw date palm sap, which can be infected with bodily fluids from bats.


The experimental antiviral drug, Remdesivir, which is being tested against the Ebola virus in the ongoing outbreak in the DRC, has also shown promise in protecting non-human primates against infection with Nipah virus. In a trial, published in Science Translational Medicine, four African Green Monkeys given intravenous remdesivir survived lethal doses of Nipah virus; the other four that did not, died within 8 days.


There are currently no vaccines or specific therapeutics against Nipah virus approved for use in humans.


CEPI has four Nipah vaccine candidates in its portfolio.

Disease X

What is it?

“Disease X” represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease. In February 2018, Disease X was included in the updated WHO R&D Blueprint list of priority diseases.


By their very nature, we cannot predict what or where “Disease X” is likely to emerge.


What we do know is that new diseases emerge all the time, from locations all around the world. Developing countries, particularly those with high rates of biodiversity, are at heightened risk, because of the increased risk of outbreaks and the limited capacity for surveillance and response in these countries.


Coronavirus Disease 2019 (COVID-19) represents a Disease X.


As COVID-19 shows, diseases do not respect borders. We need to be prepared on a global scale to respond to future outbreaks.


Responding to Disease X

To help the world quickly respond to Disease X, CEPI is funding the development of vaccine platform technologies so that we can rapidly manufacture vaccines against many different types of disease.

CEPI has initiated 9 partnerships to develop vaccines against COVID-19. The programs will leverage rapid response platforms already supported by CEPI as well as traditional approaches. The aim is to advance COVID-19 vaccine candidates into clinical testing as quickly as possible.

Rift Valley fever

What is it?

Rift Valley fever has been listed in the WHO R&D Blueprint of priority pathogens in view of its epidemic potential.


The virus—a member of the Phlebovirus genus—is transmitted by mosquitoes and blood feeding flies that usually affects animals (commonly cattle and sheep) but can also involve humans.


Most human infections result from contact with the blood or organs of infected animals but can also result from the bites of infected mosquitoes.


Where does it occur?

The virus was first identified in 1931 during an investigation into an epidemic among sheep on a farm in the Rift Valley of Kenya. Multiple outbreaks have been reported across the African continent and in Saudi Arabia and Yemen. Rift Valley fever mainly affects people living in pastoral communities in low-income and middle-income countries.


Between May and June 2018, concurrent cases of Rift Valley fever were reported in farmers in South Africa and Kenya, nearly 5000 km apart. More recently, outbreaks have also been recorded on the island of Mayotte, a French overseas territory in the Indian Ocean. In September 2019, Rift Valley fever was recorded in Central African Republic for the first time.


From 19 Sep 2019 until 11 Nov 2019, a total of 293 suspected cases of the disease, including 11 associated deaths, have been reported from 6 states in Sudan. These human cases are likely cases among goats in the areas where the human suspected and confirmed cases have been reported. Flash floods in August 2019 are believed to have favoured vector abundance, distribution, and longevity.

What does it do?

Most human cases of Rift Valley fever are mild but in a small proportion of patients severe forms of the disease can develop, which can include ocular disease, encephalitis, or haemorhagic fever, which can be lethal, killing about one in every hundred people it infects. In people who develop the haemorrhagic form of the disease, the fatality rate is as high as 50%.

How do we currently prevent infections?

Rift Valley fever vaccines have been used successfully to protect livestock, but no vaccine has been licensed for use in humans.


CEPI has two Rift Valley fever vaccine candidates in its portfolio.


What is it?

Chikungunya is a mosquito-borne viral disease first described during an outbreak in southern Tanzania in 1952. It is spread from human to human by the bites of infected female mosquitoes—mostly Aedes aegypti and Aedes albopictus.


The term Chikungunya is derived from Makonde, a language spoken in Tanzania, and means “disease that bends up the joints”. It is an apt description.


WHO has highlighted Chikungunya as a major public health risk and has stated that further research and development is needed to mitigate the risk it poses.

Where does it occur?

Chikungunya was first identified in Tanzania in 1952 and has since spread across the world. At first, sporadic outbreaks occurred in Africa and Asia.


Then in 2004 major epidemics were reported in India and on islands in the Indian Ocean. In 2013, major epidemics were reported in Central and South America.


In 2019, cases of Chikungunya have been reported globally:


Honduras (206 cases), Brazil (97 900 cases), Ethiopia (51 631 cases), Taiwan (96 cases, of which 21 are locally acquired), Thailand (9085 cases), Myanmar (97 cases, 26 confirmed), India (7 cases in Ahmedabad, Gujarat state; 74 cases in Delhi; 31 cases in Prakasam district, Andhra Pradesh state; 76 cases in Patna, Bihar state; 125 cases in Bophal, Madhya Pradesh state).


France, Spain, and the US have also reported imported cases with no local transmission.


The economic impact of this disabling disease can also be acute. The societal cost of Chikungunya in the Americas alone is estimated to be around $185 billion.


Millions of people have been affected by this disease and, today, over a billion people live in areas where Chikungunya is endemic.


Virus evolution, globalisation, and climate change could further the spread of this debilitating disease, amplifying its already substantial global public-health and economic consequences.


What does it do?

Chikungunya causes fever, severe joint pain, muscle pain, headache, nausea, fatigue and rash. Joint pain is often debilitating and can vary in duration.


The disease shares some clinical signs with Dengue and Zika viruses and can be misdiagnosed in areas where they commonly occur.

How do we currently prevent infections?

There is currently no specific antiviral drug treatment for Chikungunya nor are any vaccines currently approved for human use.


CEPI has three Chikungunya vaccine candidates in its portfolio.