H. influenzae Type B Immunization Prevention of invasive disease caused by Haemophilus influenzae type b. (Vaccine is approved for use in children 2 months through 5 years of age) A 4-dose series (0.5 mL each) given by intramuscular injection (2.3): • Primary series: One dose each at 2, 4, and 6 months of age. The first dose may be given as early as 6 weeks of age. • Booster: One dose at 15 through 18 months of age. Infants between the ages of 6 and 12 months previously unvaccinated should receive 2 injections, given with an interval of one month,...