SERUM ANTIBODIES TO DIPHTHERIA-TETANUS-PERTUSSIS VACCINE COMPONENTS IN ARGENTINE CHILDREN

The Argentine vaccination schedule against diphtheria, tetanus and per tussis (DTP) recommends three doses of DTP vaccine at 2, 4 and 6 month s of age, two boosters at 18 months and 6 years, a booster dose of tet anus vaccine every 10 years and two doses during pregnancy, To evaluat e the effect of this schedule, antibodies against pertussis toxin (PT) and filamentous hemagglutinin (FHA) and against tetanus and diphtheri a toxoids were determined by ELISA in serum samples from children (1 m onth to 6 years) who received different doses of DPT vaccine: 0 dose ( n=50), 1 dose (n=25), 2 doses (n=25), 3 doses (n=55), first and second booster (n=25); 25 pregnant women and their offspring, and 45 adults, High antibody levels against PT (>140 EU/ml) and FHA (>80 EU/ml) were recorded in mothers and in the newborn, Antibody titers against PT in creased with the number of doses given and decreased with time, Full p rotection against tetanus (titers >0.1 IU/ml) was observed in the grou p of adults (0.37 IU/ml), in mothers (4.4 IU/ml) and their newborn off spring (5.5 IU/ml), and in children after receiving the second dose of DTP vaccine (1.86 IU/ml), The immune status for diphtheria was far lo wer, as most of the groups lacked adequate protection, After the third dose of DTP vaccine, only 78% of the children had antibody titers abo ve the protective level (0.1 IU/ml), Since antibody levels considered to provide full protection were only achieved after the first booster dose of DTP vaccine, the primary three-dose schedule seems to be insuf ficient to confer adequate immunity in all vaccinees, Because of the h igh proportion of non-protected adults, a booster dose of Td vaccine s hould be considered for this group.