Antitoxin response to tetanus toxoid [TT] versus combined tetanus -reduced diphtheria [TD] vaccination in pregnant women: clinical trial

ABSTRACT

Outbreaks of diphtheria in 1990s primarily involved adults. This reflects the decline of immunity with age. It is recommended to use the combined tetanus-diphtheria toxoid [Td] instead of the monovalent tetanus toxoid [TT] whenever tetanus toxoid is indicated. The protective efficacy following the new vaccinations schedule needs to be tested. The present study aimed to compare serum levels of diphtheria and tetanus antitoxin in pregnant women receiving [Td] vaccine and those receiving [TT] tetanus toxoid vaccine. As well as, to compare the frequency of adverse events following immunization between both groups. randomized, double blind controlled trial strategy was adopted. The reference population was pregnant women attending four rural health units in Abu Homos District, Egypt. A simple randomized procedure was used to allocate enrolled subjects [n = 130] to a study group [receiving Td vaccine] and a control group [receiving TT group] in a ratio of 11. The study revealed that before the vaccine administration, the mean values of tetanus antitoxin level in the experimental group [who received two doses of Td vaccine] and the control group [who received two doses of TT vaccine] did not differ significantly. After the first dose of vaccination, the mean tetanus antibody level was significantly lower in the Td group than in the TT group [t = 5.51, p < 0.001]. However, after the second dose, the mean tetanus antibody liter for Td group rise to 5.83 +/- 3.99 lU/ml and was still lower than that for the TT group [6.9 +/- 3.27 IU/ml] but this difference was not statistically significant, [t = 1.68, P = 0.096]. There were no significant differences between the two groups as regards the occurrence of systemic adverse events following either the first dose or second dose of Td or TT vaccine. On the other hand, the frequency of local adverse events following the first dose and second dose of Td vaccine were higher than that following TT vaccine. However, the difference was not statistically significant except for occurrence of local pain. The study concluded that tetanus-diphtheria toxoid [Td] can be used instead of single tetanus toxoid [TT] to protect against both tetanus and diphtheria. The local reactions associated with Td are usually self limited and require no therapy