Susceptibility to tetanus and missed vaccination opportunities in Portuguese women.

Maternal and cord sera (96 pairs) were tested to measure antitetanus toxin IgG (ATT IgG) levels, using a commercial enzyme immunoassay. One mother had no detectable antitetanus antibody and four more had levels below those considered to be reliably protective (<160 mIU/ml). All five had been eligible for vaccination during pregnancy according to Portuguese guidelines, although one had received seven lifetime doses of TT. In maternal and cord sera, ATT IgG levels among those not vaccinated during the current pregnancy were significantly lower than among vaccinees (p < 0.0001), but there was no difference between those vaccinated once or twice during pregnancy. Among those not vaccinated during pregnancy, levels of ATT IgG decreased with time since last dose of vaccine (P = 0.0001). The total number of doses of vaccine was not significantly associated after controlling for time since last dose. Missed immunization opportunities occurred among half the women studied. Efforts to sustain protection against tetanus must be intensified.