Phoolwati Devi, 30, an accredited social health activist (ASHA) from Vardara village in the northern Rajasthan state of India, recalls ruefully how she had to discard a whole batch of COVID vaccine vials as the shots were spoiled.
The village, with a population of nearly 7,000 people, is tough to reach and is located around 340 kilometers (211 miles) from the state capital Jaipur.
"It was at the height of the second wave of COVID last year and people in the village needed the vaccines. But because of high temperatures and no electricity at the primary health center, I had to throw out the entire batch of doses," Devi said.
Solar units to store vaccines
Many of the villagers were distressed as long and frequent power outages in the area prevented the installation of refrigeration facilities in the local health center.
But it's not just about COVID vaccines.
Lata Bhai, 27, was unable to get a Tdap vaccine — which protects against tetanus, diphtheria, and whooping cough — during the third trimester of her pregnancy.
"I made several trips to the center but was told that the vaccine was not fit to be administered by the midwife. I was scared for my child," Bhai, a mother of two, said.
However, a recent collaboration between the United Nations Children's Fund (UNICEF) and the Japanese government has brought relief to the residents by setting up solar-powered refrigeration units to store vaccines.
So far, 27 such units have been established as part of the project, costing around $9.3 million (€9.3 million).
The units do not require a battery to store energy, can run efficiently in rural areas where sunshine is abundant, and are easy to install and maintain.
"Solar Direct Drive (SDD) refrigeration systems run on electricity provided by solar energy. They can keep vaccines at their appropriate temperature, without the need for electricity from a national grid. Power is stored using different non-battery-based technologies," said Anil Agarwal, a health specialist working for the UNICEF.
"We are working to ensure that children receive timely and quality vaccine services. Cold chain points play the most critical role in keeping the quality of vaccines intact and build trust in government services," he added.
Reducing vaccine wastage
India's universal immunization program is one of the largest public health interventions in the world, aiming to inoculate around 26 million infants and 29 million pregnant women annually. The vaccines administered under the program are all given free of cost.
Although India is the largest supplier of vaccines globally, producing over 60% of the world's vaccines, the rate of wastage is high.
Last year, for instance, over 6 million doses of COVID vaccine went to waste in the country. A major reason for the wastage was the lack of proper refrigeration facilities at health care centers, rendering the shots useless within a short span of time.
"Even though there are several challenges when it comes to the vaccine supply chain, one of the biggest ones is ensuring that vaccines are stored and transported at their intended temperature. If the vaccines get exposed to suboptimal temperatures, they lose their efficacy," Vikas Bajpai, a public health expert, told DW.
High temperatures and power cuts
In Rajasthan, blistering heat waves are a norm with large swaths of the state recording high temperatures of over 50 degrees Celsius (122 degrees Fahrenheit), particularly in summer months.
Long and frequent power outages in parts of the state add to the problem by making it more difficult to maintain cold temperatures for vaccine storage.
"We are always walking for kilometers at a stretch in extreme temperatures throughout the day and then racing back to Rajsamand city to bring back the left-over vaccines to ensure there was no spoilage. We were always racing against time," said Durga Gadri, an ASHA worker.
"But now with the installation of the solar-powered refrigeration systems, not only has the spoilage and wastage of the vaccines gone down, but people have been coming on their own to get vaccinated," Gadri pointed out.
Suresh Meena, a state reproductive and child health officer, echoes a similar view.
"During the monsoon season, it pours heavily in this belt leading to frequent power cuts, resulting in the damage of vaccines. But this year during the rainy season, we saw a difference at the health centers that have this equipment and a constant temperature was maintained and hardly any vaccine got wasted due to power cuts," Meena said.
The UNICEF says it now has plans to expand the program to provide solar power-based refrigeration units to public health care centers in other parts of the country.
Edited by: Srinivas Mazumdaru