Almost everyone, but in order to understand why, a little background is necessary. “Hepatitis” means inflammation of the liver, but most people know it as a viral infection affecting the liver. The most common types are Hepatitis A, Hepatitis B, and Hepatitis C, each caused by a different virus. While Hepatitis A is a self-limited disease that does not cause long-term problems, Hepatitis B and C can become chronic. Chronic Hepatitis is the leading cause of liver cancer and the most common reason for liver transplantation. Vaccines are the most important measure in reducing the number of cases of Hepatitis since there is no effective treatment for this viral infection. Vaccines are available to prevent Hepatitis A and B, but unfortunately, there is not one 
yet for Hepatitis C.
Hepatitis A Certain groups of people are at highest risk of contracting Hepatitis A. These people including those who travel or live in countries where Hepatitis A is common, use illegal drugs, or have sexual contact with someone who has Hepatitis A. A vaccine against Hepatitis A is available that is made from inactivated Hepatitis A virus. Following an injection of Hepatitis A vaccine, the body makes antibodies that provide immunity against the virus. The Hepatitis A vaccine is typically given as 2 shots, 6 months apart. The Hepatitis A vaccine also comes in a combination form, containing both Hepatitis A and B vaccine, that can be given to persons 18 years of age and older. This form is given as 3 shots, over a period of 6 months.
The U.S. Centers for Disease Control (CDC) recommends that the following groups of people receive Hepatitis A vaccination:
- All children at age 1 year
- Travelers to countries that have high rates of Hepatitis A
- Men who have sexual contact with other men
- Users of injection and non-injection illegal drugs
- People with chronic (life-long) liver diseases, such as Hepatitis B or Hepatitis C
- People who are treated with clotting-factor concentrates
- People who work with Hepatitis A infected animals or in a Hepatitis A research laboratory
Hepatitis B Hepatitis B begins as an acute infection, but in some people, the virus remains in the body, resulting in chronic disease. Hepatitis B infection is of particular concern when it affects infants or children. Should the infection become chronic, a majority will eventually develop cirrhosis of the liver or liver cancer. Hepatitis B virus is transmitted through activities that involve a puncture through the skin (e.g. accidental hypodermic needle stick) or contact with infected blood or body fluids.
The CDC’s Advisory Committee on Immunization Practices recommends that the following persons receive the vaccination against Hepatitis B:
- All infants, beginning at birth
- All children aged <19 years who have not been vaccinated previously
- Susceptible sex partners of Hepatitis B surface antigen (HBsAg)-positive persons
- Sexually active persons who are not in a long-term, mutually monogamous relationship (e.g., >1 sex partner during the previous 6 months)
- Persons seeking evaluation or treatment for a sexually transmitted disease
- Men who have sex with men
- Injection drug users
- Susceptible household contacts of
(HBsAg)-positive persons - Health care and public safety workers at risk for exposure to blood or blood-contaminated body fluids
- Persons with end-stage renal disease, including predialysis, hemodialysis, peritoneal dialysis, and home dialysis patients
- Residents and staff of facilities for developmentally disabled persons
- Travelers to regions with intermediate or high rates of endemic HBV infection
- Persons with chronic liver disease
- Persons with HIV infection
- All other persons seeking protection from HBV infection – acknowledgment of a specific risk factor is not a requirement for vaccination
The vaccination schedule most often used for children and adults is 3 intramuscular injections, the second and third doses administered 1 and 6 months, respectively, after the first dose.
The likelihood that a Hepatitis B infection will become chronic varies according to the age of the individual infected. Infected infants and children are much more likely to develop a chronic infection than adults. This fact highlights the reason why all infants, beginning at birth, should be vaccinated. Statistics indicate that Hepatitis B vaccination is making an impact, with new Hepatitis B infections decreasing by around 82% since routine vaccination of children was first recommended in 1991.