Diphtheria Antibodies Not Up To Par Prior To Fifth Vaccine Dose.(Brief Article)

2001 MAY 23 - (NewsRx.com & NewsRx.net) --

by N.R. Saltmarsh, staff medical writer - A large proportion of children who have received four doses of diphtheria-tetanus-acellular pertussis (DTaP) or diphtheria-tetanus-whole cell pertussis (DTwP) vaccine are only minimally protected against diphtheria.

Measurements of serum antibody levels taken before a fifth dose of DTaP or DTwP in children four to six years old revealed that 40% or fewer had acquired "certain, durable protection" from diphtheria, reported M.E. Pichichero and associates the United States.

They assessed antibodies to diphtheria, pertussis, and tetanus with enzyme-linked immunosorbent assay in a prospective, randomized, double-blind trial.

Although all of the children had diphtheria antibodies above the minimum protective level of 0.01 IU/ml and 86%-100% had titers >0.1 IU/ml, depending on prior vaccine product, only 0%-40% of children had titers >=1.0 IU/ml, which conferred certain, durable protection, said Pichichero et al.

The numbers were much better for tetanus, with 93%-100% of children acquiring certain, durable protection from titers >=0.1 IU/ml, but the picture was less clear for pertussis protection.

Children had uniformly low pertussis antibody titers, but parameters for certain protection have not yet been established, noted the researchers ("Fifth vaccination with diphtheria, tetanus and acellular pertussis ...