Pandemic influenza preparedness: the critical role of the syringe

Abstract

In the face of an almost unprecedented threat of a global pandemic of influenza it is imperative that stockpiling of appropriate drugs and devices begin now. One vital device is an appropriate syringe for delivering vaccine. With the potential for millions to be infected and the vaccine supply severely stretched it is imperative that the syringe used to vaccinate waste as little vaccine as possible and thus allow for a maximum number of persons to be vaccinated. Our study tested seven leading candidate vaccine syringes for dosing accuracy, dose-capacity per vial, medication wastage and a battery of ergonomic features. One device, the Flu+trade mark syringe, proved superior to the others in all important categories, possibly due to its low dead-space volume and its dosing accuracy. The data suggest that switching to this device from any of the others tested would provide between 2 and 19% additional vaccine doses per vial if the current 10-dose vials are used. Extrapolations from this data suggest that many thousands to millions of additional persons could be vaccinated in mass campaigns. Use of a syringe of this type, and the vaccine savings that would accrue, would likely be important in reducing morbidity and mortality in the event of a pandemic of influenza.

Figures

Fig. 1

A comparison of the mean weights in g of 540 doses delivered by each of the 7 devices (3780 total doses). Devices that delivers less than 0.500 g are considered to underdose (e.g. devices 3, 4 and 7), those that deliver more than 0.500 g to overdose (device 5) and those that deliver a mean closest to 0.500 g are the most accurate (e.g. devices 1 and 6). Error bars represent the 95% CI.

Fig. 2

Means of residual volumes (waste) left in vials per device category. The least wasteful are devices 1 and 2 while the others are approximately twice as wasteful. Error bars indicate the 95% CI.

Fig. 3

The means of dead-space volumes (n-40 per device) for the seven devices tested. Devices 1 and 2 had statistically significantly lower dead-space volumes than the other devices.

Fig. 4

The syringe on the left has a plunger tip that fits into the cone-shaped end of the barrel, decreasing the amount of dead (waste) space. Compare to the conventional device on the right, where a considerable amount of dead-space (red) remains when the plunger is pushed in.