Academic journal article Bulletin of the World Health Organization

Auto-Disable Syringes for Immunization: Issues in Technology Transfer

Academic journal article Bulletin of the World Health Organization

Auto-Disable Syringes for Immunization: Issues in Technology Transfer

Article excerpt

Voir page 1006 le resume en francais. En la pagina 1006 figura un resumen en espanol.


In response to a request in 1986 from WHO, various auto-disable (AD) syringe designs have been developed in accordance with a standard performance specification. WHO was concerned that conventional disposable syringes were being widely reused and believed that, unless a physical barrier to syringe reuse was introduced, economic necessity and cultural resistance to waste would ensure continued reuse in developing countries, regardless of training, advocacy and regulatory factors. The aim was to make available for immunization injections a disposable syringe and needle that could not be used more than once.

Performance and design

In 1987 a WHO panel examined 35 responses to the initial request. The proposals were made in accordance with a performance specification requiring that the syringe, once filled with a single standard dose of vaccine, would be able to deliver that dose but not a subsequent whole or partial dose. These AD syringes and over 400 other designs proposed later involved a variety of mechanisms that either immobilized the plunger, blocked the needle, or caused the syringe to leak when a second injection was attempted. The syringes were also made with a permanently fixed needle, thereby ensuring that the needle too was used only once. The performance of AD syringes has been tested in an independent laboratory (1) in order to qualify for listing in the WHO/United Nations Children's Fund (UNICEF) product information sheets that guide policy on the purchasing of equipment for immunization programmes (2). Some AD syringe designs have also been tested under field conditions (3, 4) to assess the training requirement and acceptability to health workers and managers.

Meeting the need for safety

The AD syringe prevents reuse and therefore helps to prevent transmission of bloodborne pathogens between patients. The syringe does not significantly affect transmission between patients and health workers attributable to accidental needle-stick, nor does it present a lower risk of accidents in the community when incorrectly disposed of. However, it does prevent resale after use. In many situations where syringes are commonly reused, the introduction of the AD syringe necessitates an increase in the number of syringes purchased and a corresponding increase in expenditure. The AD syringe contributes to safety predominantly in developing countries where the reuse of standard disposable syringes is widespread, disposal systems are inadequate, and the resale of used medical equipment is common.

Current policies for use of AD syringes

WHO, UNICEF and the International Federation of Red Cross and Red Crescent Societies have signed a commitment (5) to budget for and supply AD syringes and puncture-proof safety boxes with all injectable vaccines procured through them for mass immunization purposes. The determination to reduce the risks associated with the supply of disposable syringes and with the supply of inadequate numbers of syringes is being extended by WHO and UNICEF to all routine immunization with injectable vaccines. No international policies have yet been recommended to extend further the use of AD syringes to all skin injections, including all curative injections, but certain countries are considering this move and several states in the USA have recently introduced regulations in favour of safety syringes that have a specification different to that of AD syringes.

AD syringe production Market development

Despite the great number of design proposals and the existence of several hundred patents, only four models of AD syringe are currently being manufactured; two more are in the pre-production stage. This partly reflects the large investment needed to take a new design into production (usually over US$ 1 million). More important have been the small size and slow growth of this market, almost exclusively confined to the public sector, in developing countries. …

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