Currently, parents have two options for vaccinating their children against measles, mumps, rubella, and varicella, also known as chickenpox. In the US, the hepatitis B vaccine is given in the hospital shortly after birth, because the virus can be transmitted to children during delivery. A serious liver infection, hepatitis B can lead to cirrhosis and cancer. Each year in the US, an estimated 25,000 infants are born to women diagnosed with the hepatitis B virus. The World Health Organization advises a universal birth dose of the hepatitis B vaccine.