The decline in sudden infant death syndrome (SIDS) cases in Washington State in 19921 and a concurrent decline in invasive Haemophilus influenzae type b (Hib) infection in southern California2 may shed some light on a cause for SIDS. A connection may exist between the use of conjugate Hib vaccine in infants starting at age 2 months and the reduction in the number of cases of SIDS.
In October 1990, the US government lowered the age that infants could receive conjugate Hib vaccine from 15 months to 2 months and older.3 Routine immunization of infants beginning at 2 months of age has been associated in the Los Angeles, Calif, area with reductions in reported cases of Hib infection, declining from approximately 90 cases per 100 000 at 0 to 5 months of age to 50 cases in 1991, and down to 10 cases per 100 000 infants of
Sepkowitz S. Sudden Infant Death Syndrome and Haemophilus influenzae Infection. Arch Pediatr Adolesc Med. 1994;148(10):1109-1110. doi:10.1001/archpedi.1994.02170100107026