Unsterile needles and syringes may transmit blood-borne infectious agents such as HIV and hepatitis B virus. The emergence of these diseases as major public health concerns and the risk of nosocomial transmission has heightened interest in the development of single-use injection devices. WHO and UNICEF embarked on a programme to develop and introduce these devices in 1987. We report on a field trial in Karachi, Pakistan, of the SoloShot (SS) plastic disposable syringe, which has a metal clip in the syringe barrel to prevent second-time withdrawal of the plunger. A conventional disposable syringe (CS) was used as a comparison. We observed 48 vaccinators giving 2400 injections with the SS and 1440 with the CS; 98.7% of SS performed as designed. The average volume required per delivered dose was comparable for the two syringes and was delivered more quickly with SS. Training and experience had a small but statistically significant effect on several aspects of SS use. Vaccinators who indicated a syringe preference preferred SS on 7 out of 9 indicators. SS is safe and effective in preventing reuse and is easier and quicker to use than the CS. Vaccinators require little, if any, special training. It could directly replace disposable syringes in expanded programmes on immunization (EPI) in countries where use of unsterile disposable devices occurs or when sterilization is not practical.
PIP: The emergence of HIV and hepatitis B as major public health problems and the risk of nosocomial transmission demands that syringes and needles either be used one time and disposed of or reused only after thorough sterilization between patients. The World Health Organization and UNICEF launched a program in 1987 to develop and introduce single-use injection devices. Even so, incorrectly sterilized syringes and needles as well as disposables are frequently reused. Alternatives to existing injection devices are therefore clearly needed. The authors report on a field trial in Karachi, Pakistan, of the SoloShot (SS) plastic disposable syringe, which has a metal clip in the syringe barrel to prevent second-time withdrawal of the plunger. The use and acceptance of the SS was compared against that for the conventional plastic disposable (CS) syringe routinely used by the Expanded Program on Immunization in Pakistan. The SoloShot permits a single filling and emptying, after which a metal clip locks the plunger to prevent it from being drawn back a second time. A breakaway notch in the plunger inhibits twistout, while a barrier rib on the plunger guards the clip against intentional defeat. The metal clip is set to permit filling up to 0.575 ml of vaccine with an head space to allow the removal of air bubbles and adjustment for the exact dose. The clip is never in contact with the vaccine liquid. Researchers observed 48 vaccinators giving 2400 injections with the SS and 1440 with the CS. 98.7% of the SS performed as designed. The average volume required per delivered dose was comparable for the two syringes, but was delivered more quickly with the SS. Training and experience had a small but statistically significant effect on several aspects of SS use. Vaccinators who indicated a syringe preference preferred the SS on seven out of nine indicators. One may conclude that the SS is safe and effective in preventing reuse and is easier and quicker to use than the CS. Vaccinators require little, if any, special training. These encouragingly positive findings suggest that the SS could directly replace the CS in expanded programs on immunization in countries where the use of unsterile disposable devices occurs or when sterilization is impractical.