WHO and UNICEF issued a new joint policy statement about vaccine vial monitors to improve access to immunization.
Vaccine vial monitors (VVM) are used to warn health care workers if a vaccine was damaged by heat. The monitor is made of heat-sensitive material that is light in color but darkens when exposed to heat over time, which indicates the vaccine is no longer effective.
The joint policy statement urges all countries and WHO member states with access to self-procuring vaccines to use VVMs as well as the minimum requirements for vaccine purchase agreements. The statement recommends that all member states adopt vaccine management practices that include:
- Ensuring that vaccines administered have not been damaged by heat.
- Reducing vaccine wastage.
- Facilitating immunization outreach and increasing access and coverage.
- Pinpointing cold chain problems.
- Managing vaccine stocks.
- Preventing inadvertent freezing of vaccines.
VVMs react based on the level of heat stability. Vaccines from the VVM 30 high-stability category last 30 days at 37°C, 193 days at 25°C and at least four years at 5°C. Vaccines from the VVM 14 medium-stability category last 14 days at 37°C, 90 days at 25°C and at least three years at 5°C. Vaccines from the VVM 7 moderate-stability category last seven days at 37°C, 45 days at 25°C and at least two years at 5°C. Vaccines from the VVM 2 least-stable category last two days at 37°C and 225 days at 5°C.
The concept of VVMs was conceived by WHO in 1979. The first vaccine tested using a VVM was the measles vaccine that same year using a p-toluenesulfonate chemical for which product development began at the Program for Appropriate Technology in Health (PATH). At that time, the target price of VVMs was 5 cents.
In 1988, PATH identified a new core technology for VVMs using diacetylene polymers that overcame constraints of the p-toluenesulfonate technology. The new technology proved that the reaction rate was too slow to use with the oral polio vaccine, and there were dermal toxicology issue and printing difficulties. In 1994, WHO, UNICEF and oral polio vaccine manufacturers determined that VVMs must be included in all oral polio vaccines starting January 1996, with a pilot introduction in April 1995 in Tanzania and Vietnam.
Originally, WHO and UNICEF issued a joint policy statement regarding the use of VVMs with all vaccines in 1999. At a meeting that same year, UNICEF announced that VVMs would be included in all vaccines beginning in 2000. However, only three UNICEF vaccine suppliers used VVM attachments with vaccines in 2001. By 2005, 12 additional UNICEF vaccine suppliers used VVM attachments.
The future of VVMs
The policy statement recommends that all member states adopt policies in the future that permit the use of vaccines beyond the cold chain that include national immunization days, hard-to-reach graphical areas, immunizations provided in the household, cool seasons and storage and transportation of freeze-sensitive vaccines where the risk for freezing is greater than the risk for heat exposure.
Since 1997, almost 2 billion units of VVMs have been used with vaccines, celebrating 10 years of implementation. Additionally, the price of VVMs is still approximately 5 cents, according to WHO scientist Ümit Kartoglu, MD, DPH.
“This price would change depending on the quantity of labels and units the vaccine manufacturer purchases from the VVM manufacturer. I must admit that [the price] was a good guess considering that we are still within the price range when the technology was being developed,” Kartoglu said.
Since researchers rely on VVMs to sustain the use of vaccines, it is of utmost importance for health care workers to maximize the benefits of VVMs, Kartoglu said. There must be a consistent supply of vaccines with VVMs because VVM use will not be effective if health care workers receive a shipment of vaccines that include vaccines with VVMs and vaccines without VVMs.
“The WHO and UNICEF joint policy statement stresses the need for consistent supply and calls upon all member states to include VVMs among the minimum requirements for all vaccines purchased. It also urges donors to adopt a policy that explicitly calls VVMs to be included as a minimum standard in every vaccine donation,” Kartoglu said. – by Pam Rothman
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