THE KEY ROLE OF VACCINE VIAL MONITORING (VVM) FOR ROUTINE AND MASS IMMUNIZATION
By. John S. Lloyd (P.A.T.H. - Resident Advisor) April 2005
WHO VACCINE VIAL MONITOR PURPOSE
Vaccines do not change visually when they have been exposed to excessive heat and time. The operational consequences of this simple fact include the administration of heat-damaged vaccine to children and the wastage of potent vaccine erroneously of having been damaged by heat over time.
At any time in the process of distribution and at the time a vaccine is administered, the vaccine vial monitor (VVM) indicates whether the vaccine vial has been exposed to a combination of excessive temperature over time and whether it is likely to have been damaged, this information serves several important purposes in the management of the cold chain.
- Health Workers are warned when a vaccine may no longer be protective and should be administered, the use providing assurance also to the client that vaccine has not been heat-damaged at the time of administration.
- Many vaccines are discarded due to suspect heat exposure or in response to a cold chain break, whether actually damaged or not. VVMs can reduce vaccine wastage by preventing the discard of usable vaccines.
- Storekeepers are informed that certain vaccine vials have been exposed to heat over time more than others, even though they are still useable. This information enables vaccines with the shortest "life" to be prioritized for distribution and use.
- Outreach immunization services comprise a large part of total immunizations and are often conducted in remote areas, which are difficult to reach, In these operations, where the cold chain is most fragile, the VVMs indicate which vaccines may still be used, thus contributing to increased immunization access for needy populations.
- The VVM enables failures in the cold chain to be highlighted in a simple, unambiguous manner and focuses manager’s attention and resources on the weakest links in the chain. The critical information assures that failures can be prevented and that wastage of vaccine due to failures of the cold chain is minimized.
Many vaccines are damaged by freezing and the cold chain has been shown to be responsible for significant amounts of frozen vaccine due to the use of ice in transport and to guarantee storage continuity when power sources are unreliable. Changes in equipment and handling procedures to avoid freezing require the use of VVMs to monitor and avoid excessive heat exposure of these vaccines.
In summary, the VVM is an excellent monitoring device to assure that only non-heat damaged vaccine is administered to women and children. They help to extend access to immunization, they increase the efficiency and reduce wastage in the cold chain and, when visible on all vaccine vials of all types, they will help to streamline distribution systems for immunization services of the 21st century in all developing countries. |
