John Lloyd

Evidence base prompts changes to global policy for vaccine refrigerators

A month ago a document titled Power Quality Challenges in LMICs - Data and Analysis was posted here on Technet Forum. Unfortunately, there has not been much feedback.  I am disappointed in the lack of discussion because in my view this study presents findings which support changes in global policy for vaccine refrigerators. The paper presents data from two representative countries on the availability and quality of electric power that are major determinants of the performance of vaccine refrigerators. The data suggest that, in both countries, the variability and intermittent supply of electric power indicates that three features are needed, universally to assure continuous, correct refrigerated storage:

• Holdover passive cooling 
• Integral voltage stabilizers
• Remote temperature and power monitoring

Consider these three issues as a basis for discussion.

Hold-over passive cooling

The period of ‘safe’ vaccine storage when power is interrupted is boosted for vaccine storage by an ‘ice-lining’ that is charged with cooling when power supply is on or when sun is shining and then provides cooling when the power is cut. The data show that interruptions of the grid supply are variable and unpredictable. So a universal policy to provide a holdover of 120 hours might replace the current standards. The holdover capacity in hours remaining could be displayed on the refrigerator to inform the user of the security of stored vaccines.

Integral voltage stabilizers

Voltage stabilizers markedly increased the percent of usable electricity supply in all refrigerators monitored during the study, both those with widely varying voltages and those with frequent variations. At present, stabilizers may be supplied as separate accessories ‘bundled’ with refrigerator purchase or they may be provided within the refrigerator product. Incorporating stabilizers universally into vaccine refrigerators could benefit repair and maintenance and would assure that sensors were correctly installed,

Remote monitoring of temperature and power

The paper describes the system of power recording that was adopted in this study. Analysis of this data has, for the first time in over 30 years, informed manufacturers, vaccine managers and international stakeholders. Power data, when used in conjunction with temperature alarm data and vaccine management should be routinely monitored by an LMIS. The collection, transmission, analysis and dissemination of information by countries should become universal.

The WHO PQS Specification Working Group might plan a discussion on the implications of this paper for the future of a universal vaccine refrigerator specification for all countries. The benefits of a universal vaccine refrigerator might be:

• A single simple standard for all vaccine refrigerators
  • Rejecton of domestic refrigerators
  • Hybrid use of solar and grid electricity 
• Oversight of the implementation by National Regulatory Authorities
• Larger market, concentrated on a single universal standard
  • Better prices
  • More manufacturer interest

Yes, I heard the announcement too on BBC World News.

I support the motivation and interest of individual researchers and the media to anounce potential 'innovations' in a cryptic 'Breaking News' style.

In this case, as in many other releases I have read, is that the innovation is premature and vanishes as quickly as it appeared! In this case, I hope that the issues that I am about to list will be considered:

Freeze dried format is, I admit, being used in the manufacture of an increasing proportion of new vaccines. However, this format is to be avoided in the future when there is better choices because:

- Until there are vaccine delivery devices that administer powder directly in widespread use, the vaccine has to be re-constituted (mixed with diluent); 

- The reconstitution of dried vaccine with diluent at the point of use is hazardous and the procedure is slow;

- Oral polio drops are enabling us to eradicate the disease without an injection and injected, killed polio liquid will gradually take over without an additional injection;

- Although freeze drying can achieve higher thermostability in storage than some liquid vaccines, it is very heat sensitive once reconstituted and must be used within 6 hours;

- Freeze drying is an expensive process requiring long term investment by manfacturers and some loss of flexibility.

John Lloyd