The Hib vaccine protects against infections caused by the bacterium Haemophilus influenzae type b. This bacterium can lead to serious illnesses, particularly in young children, such as meningitis, pneumonia, and epiglottitis. The vaccine is typically given in a series of doses during infancy, starting at 2 months of age. The Hib vaccine is highly effective and has significantly reduced the incidence of Hib disease since its introduction. It is usually administered as part of routine childhood immunizations, often combined with other vaccines. The vaccine is safe and well-tolerated, with mild side effects like redness at the injection site.