Prevention combines vaccination, post-exposure prophylaxis and measures that interrupt transmission. Hepatitis A and B can be prevented by vaccine, and hepatitis B vaccination also prevents hepatitis D; the hepatitis E vaccine is licensed in only some countries, and hepatitis C has no vaccine, so blocking the route of spread remains essential for all of them.
Vaccination
Hepatitis A is prevented by an inactivated vaccine given as a two-dose series, with the second dose 6 to 18 months after the first. Children are vaccinated at 12 to 23 months of age, and adults at risk — travellers, men who have sex with men, people who inject drugs and people with chronic liver disease — are also vaccinated.
Hepatitis B is prevented by a recombinant vaccine that offers nearly 100% protection. It is given as a birth dose within 24 hours of delivery followed by two or three further doses, and it protects for at least 20 years and probably for life. Because HDV requires HBV, hepatitis B vaccination also prevents hepatitis D. The hepatitis E vaccine (HEV 239) is licensed in China and a few other countries and has been used to control outbreaks. There is no vaccine against hepatitis C.
Post-exposure prophylaxis
For HAV, unvaccinated contacts are offered vaccine, and in certain groups immune globulin, within 2 weeks of exposure. For HBV, exposed people who are not immune receive vaccine and, in some cases, hepatitis B immune globulin (HBIG) as soon as possible, preferably within 24 hours. Infants born to HBsAg-positive mothers receive vaccine within 24 hours of birth, with HBIG added in certain circumstances, and mothers with a high viral load can take tenofovir in the third trimester to reduce transmission.
Interrupting transmission
For the enteric viruses, safe drinking water, proper disposal of sewage and hand hygiene interrupt faecal-oral spread. For the bloodborne viruses, prevention means testing donated blood, using sterile equipment for injections, tattooing and piercing, safe disposal of sharps, and harm-reduction services for people who inject drugs, such as needle exchange and opioid agonist therapy. Condoms reduce sexual transmission of HBV and HDV and, less efficiently, of HCV.