Billions of dollars have been invested in the vaccine cold chain—a global network of cold rooms, refrigerators, carriers, and boxes that keep lifesaving vaccines at just the right temperature.
If a vaccine gets too hot or too cold on its way to the person who needs it, the active ingredients can degrade and become less effective.
Of course, a vaccine refrigerator is only as reliable as its power source. A recent survey of 730 health centers in Cambodia, Ethiopia, Kenya, Myanmar, Nepal, and Niger showed that 25 percent still had no access to electricity, and another 25 percent were regularly affected by outages and other reliability issues.
With temperature such a critical factor, some vaccine refrigerators are designed to account for unavailable or unreliable grid electricity by using gas or kerosene or solar power. Each type has its pros and cons, but one in particular—the solar direct-drive refrigerator—brings a big fringe benefit.
Harvesting energy for better health
The solar panels that power direct-drive refrigerators often gather more energy than needed to cool vaccines. Energy harvest control devices (EHCs) provide a way to use that excess electricity for other purposes at health centers.
“EHCs are really exciting,” says Steven Diesburg, PATH’s product development engineering lead. “These devices essentially add a USB port or other common power port to a health center’s existing cold chain installation, allowing health workers to power a whole host of medical devices and technologies.”
It is important to note, Steven says, that EHCs are designed to protect the vaccines first. They won’t allow users to draw on power the refrigerator needs, and they’ve been tested and approved by the World Health Organization (WHO) as peripheral devices for vaccine cold chain equipment. Plus, direct-drive refrigerators retain their own thermal backup for cooling the vaccines when the sun isn’t shining.
From power to possibility
There are approximately 7,418 health facilities in 32 countries with solar direct-drive refrigerators that could benefit from EHC devices. PATH and its partners evaluated the technology—looking to see whether EHCs performed according to WHO specifications during actual use, and how they affected health workers and health centers.
In Senegal, PATH found that depending on the complexity of the system, this extra power could be used to charge a cell phone or even allow for fans or electric lights. Sometimes this electricity was used for other health-related purposes, such as running fetal Doppler devices.
Surplus power from vaccine refrigerators can be used to charge other medical devices and technologies. Illustration: PATH/Patrick McKern.
“With the EHC project, I get light when I need it so I’m no longer worried about women giving birth at night. I can also recharge and use a Doppler, which allows me to better care for pregnant women during prenatal consultations,” reflected Mustapha Mbaye, head nurse at the Kohel health post in Senegal.
“I can recharge and use a Doppler, which allows me to better care for pregnant women during prenatal consultations.”— Mustapha Mbaye, head nurse, Kohel health post, Senegal
Although WHO outlines requirements for the safety and robustness of EHCs, there are currently no restrictions on how health care workers can use the available power. Because the use of EHC devices are not restricted, health workers can be creative about how the extra power could be used.
“I am excited about the potential of EHCs to democratize power,” said Steven. “What if health centers could offer access to electricity in addition to improved health services? This technology could turn them into a gathering place at the center of the community.”
