Efforts to vaccinate essential workers in Namibia and other developing countries have only just begun. By current estimates, achieving Covid-19 herd immunity (to current strains) will require at least 75% of the world’s population to be vaccinated. Some developing countries haven’t reached that level of coverage even for common vaccine-preventable diseases like measles and polio.
While many developing countries just started to receive their Covid-19 vaccines through donations and under COVAX, the success of national distribution efforts depends on a functional cold chain. This is an uninterrupted system of storage, transport and delivery of vaccines at low temperatures all the way from national warehouses to local clinics and into the arms of people.
Most vaccines must be stored between 2°C and 8°C. This is the case for polio and measles vaccines as well as the Covid-19 vaccines from Johnson & Johnson and AstraZeneca-Oxford. Others have temperature requirements that are notoriously more difficult to maintain. The vaccines from Moderna must be stored at between -25°C and -15°C. The Pfizer-BioNTech requires -70°C, but can be kept between -25°C and -15°C for up to two weeks.
Keeping vaccines seamlessly refrigerated is an especially daunting challenge where electricity is unavailable or unreliable. A 2013 review spanning 11 African countries found that just 28% of clinics and hospitals had reliable electricity, and 26% had no electricity access at all. Updated data on energy access in health facilities is scattered and sparse, but we are working on a new comprehensive review.
Unreliable power is extremely costly for vaccination efforts. Each year, nearly 50% of freeze-dried and 25% of liquid vaccines are wasted. This is in large part due to cold chain electricity disruptions.
Thus, to deliver Covid-19 vaccines at the required scale, the problem of energy access at health facilities must be confronted. But realistically, entire national grids can’t be overhauled overnight to provide universal, uninterrupted power. So what can be done?
In many cases, the answer may be to go solar. Solar photovoltaic solutions, like other decentralised renewable energy systems, come in countless configurations. These typically include battery storage and can be used along with existing electricity sources like the national grid or a diesel generator.
This flexibility means that photovoltaic systems can be deployed rapidly and modularly to provide health facilities with power, often more reliably than the grid. Electricity is essential for vaccine cold chain and other services needed during a pandemic.
Health facilities in areas with limited electricity have long relied on gas-powered “absorption type” refrigerators. Solar-powered refrigerators are more reliable and efficient. Photovoltaic refrigerators with batteries store energy from solar panels for later use. In this way power is available even on cloudy days or at night, or (for grid-connected clinics) during a power outage.
Other photovoltaic refrigerators do not use batteries at all. Solar direct drive refrigerators use solar energy to directly freeze water into an ice wall. This keeps the storage container cold for days, even when solar energy isn’t available.
Most solar refrigerators are equipped to store vaccines only at standard temperatures (between 2°C and 8°C). Solar-powered solutions for subzero storage and transport are available, though not yet at wide scale. For example, the MOTE vaccine cooler, developed by Nigerian startup Gricd, has solar-powered batteries that can maintain stable internal temperatures as cold as -20°C for up to 24 hours.
Solar power can also help with another essential electricity-dependent component of vaccine delivery systems: information and communication technologies. These enable national health programmes to monitor vaccine stocks and refrigerator temperatures in remote, rural health facilities in real time, and alert them when deviations occur that may compromise their integrity.
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