From Production to Patient: Transport

3.4 billion people -half of the world’s population- is at risk of contracting malaria. An estimated 627,000 deaths were due to malaria alone, over 90% of which occurred in sub-Saharan Africa. Up until recent breakthroughs in medical science, the possibility of a malaria vaccine was almost unheard of. The prospect of saving millions of lives drives many to wonder: how are vaccines made and transported? What is or isn’t necessary to ensure proper standards are being met?

Our last post discussed how vaccines and antigens are produced, but now it’s time to pack and ship them. Unlike chemical drugs, many biological preparations are unstable during storage and this instability can reduce the safety and efficacy of medicinal products. Proteins and other macromolecules may be sensitive to heat, light, radiation, changes in the environment, or they may interact with the container materials or other components of the vaccine mixture.

Significant changes in stability occur following exposure to temperature stresses exerted through fluctuations in handling or storage conditions. This could mean the difference between a vaccine that saves a life, and one rendered entirely inert. To prevent this, something called the cold chain was developed.

The cold chain is the path in which vaccines and other delicate, temperature-sensitive materials go in order to assure proper potency: it is an uninterrupted series of storage and distribution activities which maintain a given temperature range. Since one too many temperature excursions can promote mold growth and protein degradation, the cold chain allows for vaccines to stay within safe margins. Best practices state that an adequate supply of packing materials (e.g.; coolers, cold packs, barriers) should be available to move vaccines at any given moment if needed. In places like Europe and Canada, packaging is not considered as much a concern, but regulations on frozen vaccines differ. In countries like Canada, vaccines that have become frozen are to be immediately disposed of rather than go for further testing.

Mobile refrigerators are vital to moving vaccines from place to place in such a way that meets appropriate compliance standards. Most medical fridges and freezers include built-in fans to circulate cold air as well as backup batteries. These fans eventually fail, generating heat from the motor while the fan isn’t operating. This can cause unbalanced temperature readings and quickly ruin stores of vaccines without informing anyone.

Vaccines should be checked before and after movement from one facility to another as well as before leaving transportation vehicles. This is to ensure vaccines have not been broken, contaminated, or otherwise compromised, but the small volume of portable fridges can cause false positive readings. Buffer vials are a cost-effective, power-saving solution to constantly opening and closing the doors of portable refrigerators. Buffer vials use sand or glycol solution to give a precise reading of the actual temperature in cooling units, not just a brief spike from a door opening. 

Reliable temperature readings are especially vital in the case of prototype vaccines. GlaxoSmithKline's malaria vaccine functions by destroying the parasite before it begins multiplying in the liver and cycling back into the bloodstream, where it can infect red blood cells. This breakthrough vaccine could be rendered ineffective or even harmful from a simple temperature breach in a cooling unit, putting many lives at risk.

Vaccine fridges and freezers often use data loggers to track temperatures over time, but they are not without their problems too. Small, portable data loggers often compile information as an average temperature displayed on a digital readout to keep temps in check. This sounds fine at first but given the delicate nature of vaccines, even short excursions can initiate mold growth and ruin product. The awful part is that data loggers could read only slightly above normal because they use an aggregated average for that day. This means that unless contamination was visibly evident, vaccine providers could easily give compromised vaccine to patients. SmartSense's model works well for logging data for the long term as well as sending alerts via phone, text message, or email when temperatures reach dangerous thresholds.

By following the cold chain and using the appropriate monitoring equipment, vaccines are brought where they are needed most; even on opposite ends of the globe. Stay tuned for the conclusion of Production to Patient to learn about the best long-term storage and administering practices!