Vaccine vial monitor availability and use in low- and middle-income countries: A systematic review

Introduction: The vaccine vial monitor (VVM) registers cumulative heat exposure on vaccines over time. As low- and lower-middle-income countries transition beyond support from the Global Alliance for Vaccines and Immunization (Gavi), they will assume full responsibility for vaccine financing and procurement. It is unclear to what extent countries transitioning out of Gavi support will continue to include VVMs on their vaccines. This paper aims to systematically review evidence on VVM availability and use in low- and middle-income countries to document factors behind global access to and country demand for VVMs. Such results could help identify actions needed to ensure continued use of VVMs in countries that transition out of Gavi support. Methods: We performed a systematic review of electronic databases, reference lists, and grey literature in English and French languages with publication dates from 2005 onwards. The studies included were analyzed for the following outcomes: (1) availability and deployment of VVM-labeled vaccines; (2) VVM practices and perceptions in the immunization system; (3) vaccine introduction and decision-making processes; (4) Gavi graduation and vaccine program sustainability. Results: The study found that VVM availability and use was affected by multiple sourcing of vaccines and the extent to which VVM was included in the vaccine specification in the tendering documents when procuring vaccines. Knowledge about VVM and its impact on the EPI program was found to be high among health workers as well as decision-makers. However, the study also found that weak capacity in key national institutions such as NRA and NPA might impact on demand for VVM. As countries take decisions regarding the adoption of new vaccines, factors such as disease burden and vaccine price may assume greater importance than vaccine characteristics and presentation. Finally, the study found that countries rely largely on the advice and recommendations from technical partners such as WHO and PAHO. Conclusion: The study concludes that global access to and country demand for VVM are dependent on policy statements and recommendations about VVM by key policy institutions such as WHO and UNICEF. The study also concludes that despite Gavi-eligible countries having access to VVM-labeled vaccines, inclusion is often below 100%. Weak institutional capacity in key national agencies such as NRA and NPA seems to be a contributing factor, while other factors include the procurement of clear national policies on the inclusion of VVM on vaccines, along with the capacity to enforce the policy. Finally, the study concludes that knowledge about VVM and its impact on vaccine program efficiency, safety, and cost is critical for transitioning countries’ continuous demand for VVM.