Present and future challenges of immunizations on the health of our patients.

A recent analysis demonstrated a change in incidence approaching 100% for diseases against which we routinely immunize in the United States. At present, measles, mumps, rubella, invasive Haemophilus disease, poliomyelitis, diphtheria and tetanus are well-controlled but not eliminated. Diseases that now pose special problems include pertussis, hepatitis A and B and varicella. The incidence of pertussis surged in 1994, possibly in part because of waning immunity in the immunized population. Acellular pertussis vaccines are available for booster doses in children but are not now recommended for adults. Licensure of acellular pertussis vaccines for primary immunization of infants is eagerly awaited. Recombinant hepatitis B vaccine has been licensed for more than 10 years but there has been little change in disease incidence in the United States. Routine immunization of infants is now recommended but concerns exist about cost and persistence of immunity into adolescence. Inactivated hepatitis A vaccines appear to be highly effective in preventing clinical hepatitis and controlling epidemics. Potential target populations include military personnel, day-care attendees and travelers. Hepatitis A vaccine may be recommended for all children after approval by the United States Food and Drug Administration and if a combination vaccine becomes available. A live, attenuated varicella vaccine developed in 1974 and unlicensed in the United States is safe and highly effective in preventing varicella in healthy and immunocompromised populations. It also appears to reduce subsequent development of herpes zoster. Vaccines against pneumococci (conjugate vaccine), respiratory syncytial virus, rotavirus, tuberculosis and human immunodeficiency virus are needed. Research and technology to develop these vaccines must be developed, and efficient delivery mechanisms must be created and implemented.