NIAID supports and conducts research on each of the five known hepatitis viruses—A, B, C, D, and E. During the past 60 years, NIAID-supported investigators have been involved in many important breakthroughs in hepatitis research, including the discovery of the hepatitis A and E viruses, the development of one of the first diagnostic tests for hepatitis A, and studies that led to the creation of the hepatitis A vaccine and laid the foundation for advanced development of a hepatitis E vaccine. Commensurate with the magnitude of the medical burdens imposed by these viruses, the greatest emphasis is placed on the study of hepatitis C and hepatitis B viruses, focusing on the immune response to infection, pathogenesis and development of novel therapeutics and vaccines.
Although a vaccine to prevent hepatitis B infection is available, hepatitis B-induced liver cirrhosis and liver cancer kill about 3,000 people in the United States and roughly 620,000 people worldwide each year.
The virus can be spread
- From mother to child during childbirth
- Through sex with an infected partner
- Through contact with the blood of an infected person
- By sharing needles, syringes, razors, or toothbrushes with an infected person
Co-infection with hepatitis B virus and HIV is common.
NIAID is working with researchers in academia and the pharmaceutical industry to screen hundreds of new drug compounds for potential antiviral activity against hepatitis B. The goal is to find new treatments that will work alone or in combination with current drugs to reduce or resolve chronic infections.
Hepatitis C virus can be spread
- Through contact with the blood of an infected individual, such as through sharing needles when injecting drugs
- By unsafe injection practices in healthcare facilities
- In mother-to-child transmission during childbirth
- Through sexual contact with an infected partner
NIAID supports studies, including research at five Hepatitis C Cooperative Research Centers across the country, that focus on the immune response to hepatitis C virus infection. Several newly developed drugs can now cure more than 95% of all treated patients. However, a vaccine to prevent hepatitis C is urgently needed. A large proportion of people do not know that they are infected and therefore continue to spread the virus. People who are cured also can be re-infected if re-exposed.
NIAID-supported researchers recently completed a Phase 1/2 clinical trial of an investigational vaccine to evaluate its safety, tolerability and efficacy in preventing chronic hepatitis C infection. Although the trial did not show that candidate vaccine to be effective, NIAID continues to support efforts to develop a hepatitis C vaccine. Additionally, NIAID researchers are looking for biomarkers that may help predict progression to hepatitis C-associated liver cancer.
Hepatitis E virus is transmitted by ingestion of contaminated water or food, usually in areas where there is poor sanitation. Hepatitis E is rare in the United States but prevalent in south and central Asia, sub-Saharan Africa and the Middle East.
Although most people with hepatitis E recover from the infection, studies have found that pregnant women infected with hepatitis E virus during the second or third trimester can have a higher rates of mortality (10% to 30%) or miscarriage. Their babies face increased risk of poor health and birth defects. NIAID-funded researchers have suggested that micronutrient deficiencies may have a role in these outcomes. Hepatitis E can also cause serious illness in people with preexisting chronic liver disease resulting in hepatic failure and death. A vaccine against hepatitis E has been developed and licensed in China. NIAID has initiated a Phase I trial of this vaccine, to test its safety in healthy adults in the United States.