Programs that inoculate infants and young children to prevent them from contracting diseases to which they are particularly susceptible including diphtheria, tetanus (lockjaw), measles, mumps, chicken pox (varicella), rubella (German measles), whooping cough (pertussis), Hib (haemophilus influenzae type B), hepatitis B, pneumococcal infections and polio. Hepatitis A vaccine is recommended for use in selected locales and for certain high-risk groups. Influenza vaccine is recommended annually for children older than six months with specific risk factors. Rotavirus vaccination (to prevent acute gastroenteritis with vomiting and severe diarrhea) is recommended during the first year of infancy. A baby should receive two or three doses depending on the brand used. Some childhood immunizations involve a series of doses at specific intervals.