MODEL RELEASED. Hepatitis A and typhoid vaccine. Healthcare worker holding a syringe containing Hepatyrix. This vaccine protects against Hepatitis A, an infectious liver disease caused by the hepatitis A virus (HAV), and typhoid, a disease caused by the bacteria Salmonella typhi that causes intestinal bleeding and can be fatal. Both are transmitted through contaminated food and water. Hepatyrix is usually only administered when travelling to high-risk areas where the diseases are more common.