The number of people hospitalized in the United States with the hepatitis A virus (HAV) significantly dropped between 2002 and 2011, according to findings in the journal Hepatology.

A study by the U.S. Centers for Disease Control and Prevention (CDC) shows hep A cases have decreased by 90 percent nationwide in the past 20 years. The CDC estimates there are still about 2,000 new HAV cases in the United States each year. Worldwide, it is estimated that 1.4 million people contract the virus annually.

HAV is transmitted by ingesting contaminated food or water, or via direct contact with a person carrying the virus. There is a hep A vaccine.

Study results also show that the hospitalization rate for hep A has decreased from 0.72 to 0.29 cases per 100,000 in the population. The patients most at risk for HAV hospitalization were older, unvaccinated adults and people with chronic liver diseases like the hepatitis B virus (HBV) and the hepatitis C virus (HCV).

The study authors suggest adult vaccination may help prevent hep A, especially among those considered to be at a high risk of infection or complications.