Performance and potency of tetanus toxoid: implications for eliminating neonatal tetanus

Neonatal tetanus (NT) is a major cause of mortality in developing countries, with over 400,000 deaths estimated to occur annually. WHO has adopted the goal of eliminating NT worldwide, and a major strategy for its prevention is the administration of at least two properly spaced doses of tetanus toxoid (TT) to women of childbearing age in high-risk areas to protect passively their newborns at birth. In certain countries the locally produced TT vaccine has been shown to be subpotent, while other countries have reported NT among infants born to vaccinated women. An extensive review of production and quality control procedures was carried out between 1993 and 1995 in 8 of 22 TT-producing countries that also report NT cases, with a more superficial assessment being carried out in the remaining 14 countries. Only 4 of the 22 countries have a functioning national control authority to monitor TT production and vaccine quality. A total of 80 TT lots from 21 manufacturers in 14 of the 22 NT-reporting countries were tested for potency. Of these, 15 lots from eight manufacturers in seven countries had potency values below WHO requirements. TT potency can also be compromised by improper vaccine handling. To eliminate neonatal tetanus worldwide requires assurance that all doses of TT meet WHO production and quality requirements and that the field effectiveness of TT is monitored through systematic NT case investigations and assessment of coverage.

PIP:

Neonatal tetanus (NT) causes an estimated 400,000 deaths annually in developing countries. One major way to prevent NT is to administer at least two properly spaced doses of tetanus toxoid (TT) to women of childbearing age in high-risk areas in order to passively protect their newborns at birth. However, locally-produced TT vaccine in some countries has been found to be subpotent, while other countries have reported NT among infants born to vaccinated women. An extensive review of production and quality control procedures was conducted between 1993 and 1995 in 8 of 22 TT-producing countries which also report NT cases. A less exhaustive examination was conducted in the other 14 countries. Among the 22 countries which both report NT cases and produce TT, only Brazil, India, Indonesia, and Mexico have fully functioning national control authorities to monitor TT production and vaccine quality. 80 TT lots from 21 manufacturers in 14 of the 22 countries were tested for potency. 15 lots from 8 manufacturers in 7 countries had potency values below World Health Organization (WHO) requirements. TT potency can also be compromised by improper vaccine handling. If NT is going to be eliminated worldwide, all doses of TT must meet WHO production and quality requirements. Moreover, the field effectiveness of TT must be monitored through systematic NT case investigations and the assessment of coverage.