Vaccines are back in the news, whether an Ebola vaccine or advocacy for vaccine use in general. This news focus is much needed, particularly to highlight the importance of safeguards surrounding cold chain in handling vaccines. As the Head of Metrology at Fisher BioServices, the one constant, central, critical, working variable in my life is maintaining materials at the correct temperature, from point A to point B, and effective vaccines require effective temperature control.
Consider a news article titled Heat Blamed for Spray Vaccine's Failure against Swine Flu, published February 26, 2015 in the health section of the New York Times. The article highlighted the critical nature of temperature and its impact on vaccine potency. Additionally, it explored the temperature challenge faced by the vaccine manufacturer, who investigated and concluded that a portion of the vaccine could not be used. The vaccine is unusually sensitive to heat, and according to company officials, the doses distributed on hot days were least effective because they degraded and lost potency.
Several guidance documents have been published that include very specific instructions surrounding vaccine storage and handling. For instance, the Centers for Disease Control (CDC) issued a guidance document focused on shipment of small pox vaccine. In this document, the critical components of cold chain are highlighted and inform the readers that it is their responsibility to determine that the cold chain has been maintained.
Before we dive further in, keeping vaccines at proper temperature at all times is called maintaining the cold chain. The cold chain begins at the manufacturer and continues through storage, distribution, and use at a clinic or a physician’s office. In today’s marketplace, there are a plethora of “cold chain solutions” in the form of pre-qualified shipping systems that cater to this ever growing demand to ensure that the cold chain isn’t broken during shipping and distribution. Many of the products rely on the use of a continuous temperature monitoring device during transit, to allow the final recipient to determine whether or not the product was maintained at correct temperature during the transit. Temperature excursions are both common and expected, and these devices are intended to help prevent administration of ineffective vaccine.
A number of temperature indicators will record temperature readings inside your package, including several for use in large shipping boxes. But these only accurately represent the temperature of the product close to the probe, and may not verify that every single dose in a shipment has arrived in acceptable condition. For this—and I am opinionated in the regard—nothing is better than a vaccine vial monitor.
What is a vaccine vial monitor?
A vaccine vial monitor (VVM) is a simple label containing a heat sensitive material that registers cumulative heat exposure over time. Small enough to place on every individual dose, the combined effects of time and temperature cause the inner square of the VVM to darken, gradually and irreversibly. A direct relationship exists between the rate of color change and temperature—the higher the temperature, the faster the color changes. VVMs give the end user visual confirmation, dose by dose, that the drug product is acceptable for use.
The figure below explains the interpretation of VVM.
I am an advocate for the wider use of vaccine vial monitors given the benefit of dose-level temperature monitoring. However, economics also support use of VVM.
Consider that the price of a VVM label is likely to be in the range of 4¢ to 8¢ (calculated in US$); in 2007, UNICEF procured 3.2 billion doses of vaccine, primarily in 10-dose vials. The cost of using VVMs can be estimated at $12.8 to $25.6 million, less the baseline cost of conventional labels. This cost is a fraction of the total spent by UNICEF ($617 million) for vaccine in 2007.
It’s important to remember that the VVM does not register information about other factors that contribute to vaccine degradation, such as sunlight and age (time). Nor can monitoring devices that are enclosed in a shipment. But VVM are critical for dose-level monitoring of cold chain. It’s important to remember that the reactions of VVM’s will vary given the way they are used, as vaccines made by different manufacturers may have different heat stability characteristics.
I leave you with the following thought in conclusion; temperature is the most critical variable and greatest risk associated with vaccine distribution and quality. I see vaccine vial monitors as catalysts for much needed change in vaccine distribution cold chain. What are you doing to manage your risk? Think Temperature! To learn more about maintaining temperature throughout logistical activities, please read my eBook Cold Chain Qualification: 5 Questions You Must Ask When Shipping Biologics!