Varicella vaccine was licensed in March 1995 and recommended for limited use the same year (CDC, 1995).
Hepatitis A vaccine gained recommended status in 1996 (CDC, 1996).
ACIP added rotavirus vaccine to the childhood schedule in August 1998 and then removed it in July 1999 because of indications of increased risk of bowel obstruction during the first few weeks after its administration (CDC, 1999b).
DTaP, with an acellular form of pertussis, has replaced DTP as the recommended vaccine against diptheria, tetanus, and pertussis (CDC, 2000b).
In 1999, inactivated poliovirus vaccine (IPV) was recommended for the first two doses of poliovirus vaccine instead of oral poliovirus vaccine (OPV) (CDC, 1999c). As of January 2000, IPV was recommended for all four doses (CDC, 2000b).