Vaccines for women to prevent neonatal tetanus

Abstract

Tetanus is an acute, often fatal, disease caused by an exotoxin produced by Clostridium tetani. It occurs in newborn infants born to mothers who do not have sufficient circulating antibodies to protect the infant passively, by transplacental transfer. Prevention may be possible by the vaccination of pregnant or non-pregnant women, or both, with tetanus toxoid, and the provision of clean delivery services. Tetanus toxoid consists of a formaldehyde-treated toxin which stimulates the production of antitoxin. To assess the effectiveness of tetanus toxoid, administered to women of childbearing age or pregnant women, to prevent cases of, and deaths from, neonatal tetanus. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2012), The Cochrane Library (2012, Issue 10), PubMed (1966 to 31 October 2012), EMBASE (1974 to 31 October 2012). We also used the results from handsearching and consultations with manufacturers and authors. Randomised or quasi-randomised trials evaluating the effects of tetanus toxoid in pregnant women or women of childbearing age on numbers of neonatal tetanus cases and deaths. Three review authors independently assessed trials for inclusion and trial quality, and extracted data. Two trials (10,560 infants) were included. It should be noted that these trials are very old,1966 and 1980 respectively, and one trial randomised exclusively non-pregnant women. The main outcomes were measured on infants born to a subset of those randomised women who became pregnant during the course of the studies. One study (1919 infants) assessed the effectiveness of tetanus toxoid in comparison with influenza vaccine in preventing neonatal tetanus deaths. After a single dose, the risk ratio (RR) was 0.57 (95% confidence interval (CI) 0.26 to 1.24), and the vaccine effectiveness was 43%. With a two- or three-dose course, the RR was 0.02 (95% CI 0.00 to 0.30); vaccine effectiveness was 98%. No effect was detected on causes of death other than tetanus. The RR of cases of neonatal tetanus after at least one dose of tetanus toxoid was 0.20 (95% CI 0.10 to 0.40); vaccine effectiveness was 80%. Another study, involving 8641 children, assessed the effectiveness of tetanus-diptheria toxoid in comparison with cholera toxoid in preventing neonatal mortality after one or two doses. The RR was 0.68 (95% CI 0.56 to 0.82); vaccine effectiveness was 32%. In preventing deaths at four to 14 days, the RR was 0.38 (95% CI 0.27 to 0.55), and vaccine effectiveness 62% (95% CI 45% to 73%). Available evidence supports the implementation of immunisation practices on women of childbearing age or pregnant women in communities with similar, or higher, levels of risk of neonatal tetanus, to the two study sites. More information is needed on possible interference of vaccination by malaria chemoprophylaxis on the roles of malnutrition and vitamin A deficiency, and on the quality of tetanus toxoid production and storage.