POST 01026E : T SERIES VACCINE EFFICACY

POST 01026E : T SERIES VACCINE EFFICACY Follow-up on Post 01021E 16 December 2006 _______________________________________ NOTE : Secretariat reminds you to participate in the Technet survey. If you also know colleagues who are not members, please invite them to do so using the non-subscriber's form. Please visit : http://www.who.int/immunization_deliver ... index.html ---------------------------- After a short comment by Michel Zaffran (mailto:[email protected]), Jos Vandelaer (mailto:[email protected]) from UNICEF/WHO replies to Jedeth Mamora _______________________________________ The tetanus module of the serie on immunological basis for immunization is indeed the best reference. Michel Zaffran GAVI Alliance ----------------------------------- The moderator is correct: the "Immunological Basis of Immunization (module 3)" gives a good overview of duration of protection and issues involved. An updated version of this document is being finalized and will be published in the coming months and will provide additional information. Nevertheless, quite a number of issues remain unclear when it comes to duration of protection. That is partly because the studies that have looked at this are often difficult to compare (e.g. they are based on different schedules, different intervals between doses, different ages at which the vaccine is given, different vaccines, different serology tests used to measure antitoxin levels etc. ), but also because "protection" is a relative notion. Although there is general consensus that antitoxin levels of 0.01 IU/ml are required to provide protection, this "cut-off" is not so absolute, and whether someone is protected will also depend on the "attack load" with tetanus toxins. Needless to say that all this makes interpretation of data on duration of protection difficult. WHO has tried to provide countries with some guidance on duration of protection: see the WHO document "Core Information for the development of immunization policy" (Table 7) (available at http://www.who.int/vaccines-documents/DoxGen/H3DoxList.htm.). The duration of protection in that table is considered the minimum duration, and often duration may actually be longer. WHO has traditionally focused on strategies aimed at preventing maternal and neonatal tetanus, and is therefore recommending TT-containing doses in pregnancy or among women of child bearing age. (see table 7 in the "Core Information"). However, recognizing that also tetanus in other age groups needs to be prevented, and in order to address the situation that more and more young adults have now been immunized in childhood with DTP, WHO is recommending booster doses around school-entry age, adolescence and in early adulthood. Please refer to the WHO position paper on tetanus, published earlier this year (http://www.who.int/immunization/documen ... index.html ). In the end it is up to individual countries to adopt a schedule to fits their needs best. There are therefore different ways that countries use to ensure their population is protected against tetanus. A number of countries may use a 5-yearly or 10-yearly booster dose, while others use a school-based approach, or post-trauma immunization to provide boosters. For further links to tetanus-related documents, you can also visit the following site: http://www.who.int/immunization_monitoring/diseases/MNTE_resources/en/index.html I hope this helps. Best Regards, Jos Vandelaer UNICEF Sr Project Officer, based in WHO Geneva ______________________________________________________________________________ All members of the TechNet21 e-Forum are invited to send comments on any posting or to use the forum to raise a new discussion or request technical information in relation to immunization services. The comments made in this forum are the sole responsibility of the writers and do not in any way mean that they are endorsed by any of the organizations and agencies to which the authors may belong. ______________________________________________________________________________ Visit the TECHNET21 Website at http://www.technet21.org You will find instructions to subscribe, a direct access to archives, links to reference documents and other features. ______________________________________________________________________________ To UNSUBSCRIBE, send a message to : mailto:[email protected] Leave the subject area BLANK In the message body, write unsubscribe TECHNET21E ______________________________________________________________________________ The World Health Organization and UNICEF support TechNet21. The TechNet21 e-Forum is a communication/information tool for generation of ideas on how to improve immunization services. It is moderated by Claude Letarte and is hosted in cooperation with the Centre de coopération internationale en santé et développement, Québec, Canada (http://www.ccisd.org) ______________________________________________________________________________