A comparison was made of antibody production by newborn infants and by older children following prophylactic inoculation against diphtheria, tetanus and pertussis. In all instances the same triple combined antigen ("Alhydrox") was used, and the same routine was followed. First injection of vaccine was administered to all newborn infants at seven days of age. Most of the "older" children were between six and 12 months of age at first injection.
Incidence and severity of systemic reactions to administration of the triple combined antigen increased with subsequent injections in newborn infants; the reverse was true of the "older" children. No such difference was found between the two age groups in local reactions to inoculation. Five sterile abscesses were observed in the newborns; none in the "older" children.
Pertussis agglutinin titers achieved after immunization were consistently higher (even after booster dose) in "older" children than in infants injected in the newborn period.
"Older" children produced significantly higher diphtheria antitoxin titers after prophylactic injection than the newborn infants. After administration of a booster dose, however, diphtheria antibody production in the two age groups was comparable.
No difference was found at any time in tetanus antitoxin levels achieved after inoculation by the newborn infants and the "older" children.
It was concluded that during the first year of life the capacity to produce antibodies in response to an antigenic stimulus increases with advancing age. It was felt, however, that in some instances the immunologic handicap due to tissue immaturity can be overcome if a sufficiently great antigenic stimulus is given.
Evaluation of antibody titers achieved by newborn infants after prophylactic injection of triple combined antigen reveals that the results of immunization against tetanus and diphtheria were satisfactory. The results of inoculation against pertussis were considered to be unsatisfactory, mainly because the proportion of infants who produced "protective" agglutinin titers fell far short of the 90% which is the maximum that can be expected.
A conservative approach to the problem of active immunization in early infancy is urged. It is suggested that until further work is done, routine prophylactic inoculations not be started before the age of three months.
- Received July 6, 1948.
- Copyright © 1949 by the American Academy of Pediatrics