The only way you can get hepatitis D virus (HDV) is to also have hepatitis B virus (HBV) or to acquire it along with HBV. In other words, HDV can’t exist without HBV. Known as “delta hepatitis,” HDV is spread the same way HBV is. Both viruses are transmitted via hep B–positive blood, semen or other body fluids.

People who have not been infected with HBV can be vaccinated against that virus, which also protects them from acquiring HDV. People who have HBV may reduce their risk of acquiring HDV by avoiding exposure to blood and body fluids.