A pentavalent vaccine, also known as a 5-in-1 vaccine, is a combination vaccine with five individual vaccines conjugated into one. Pentavalent vaccine frequently refers to the 5-in-1 vaccine protecting against diphtheria, tetanus, whooping cough, hepatitis B and Haemophilus influenzae type B, which is generally used in middle- and low-income countries, where polio vaccine is given separately. By 2013, pentavalent vaccines accounted for 100% of the DTP-containing vaccines procured by UNICEF, which supplies vaccines to a large proportion of the world's children.