Hepatitis B is a virus that can damage the liver and lead to lifelong health problems. The hepatitis B vaccine prevents short-term illness (acute hepatitis) and a life-threatening infection called chronic hepatitis B . Newborns need the hepatitis B vaccine soon after birth. That's because they could be unknowingly exposed to the virus during labor or shortly after coming home. Testing for hepatitis B during pregnancy or delivery can be helpful, but sometimes results aren’t ready in time or the