J. Isacson et al., SAFETY, IMMUNOGENICITY AND AN OPEN, RETROSPECTIVE STUDY OF EFFICACY OF A MONOCOMPONENT PERTUSSIS TOROID VACCINE IN INFANTS, The Pediatric infectious disease journal, 13(1), 1994, pp. 22-27
One hundred forty-five infants were vaccinated with 25 mu g of pertuss
is toroid (NICHD-Ptxd) at 3, 5 and 7 or at 3, 5 and 12 months of age.
One month after the third vaccination all had high serum IgG and neutr
alizing antibodies (antitoxin) against pertussis toxin. Vaccination at
3, 5 and 12 months resulted in higher antibody titers than vaccinatio
n at 3, 5 and 7 months. Sera obtained from 109 children at 3 years of
age showed a decline of antibodies, but all had detectable antibodies.
Adverse reactions were confined to local redness and swelling, which
exceeded 2 cm after 17% of all injections. When the children were 3 ye
ars old, a comparison was made of the incidence of clinical pertussis
in 142 of the 145 vaccinated children and in 284 age-matched controls
living in the same areas. Information on symptoms of pertussis was obt
ained from the parents during telephone interviews. None of the vaccin
ated children had clinical pertussis, defined as a 6-week course of pa
roxysmal cough with whooping attacks or vomiting, whereas 57 controls
(20%) had experienced these symptoms. Sixteen vaccinated children were
exposed to pertussis in the household. Two of them had laboratory-ver
ified Bordetella pertussis infections with cough of 2 and 4 weeks, res
pectively, without whooping attacks or vomiting, whereas 14 did not de
velop a cough. The study shows that NICHD-Ptxd is immunogenic in infan
ts and that it most likely confers a high degree of protection against
pertussis.