Vaccines become ineffective if not stored at the correct temperature
A vaccine fridge produced by a Gwynedd company will be used to prevent disease in remote areas of hot countries where there's no reliable power supply.
The SureChill fridge, developed and made by True Energy in Tywyn, can maintain the required temperatures for up to 10 days without power.
Stewart Jones of True Energy said: "This month will see the first units being shipped to Vietnam and Senegal. "It's extremely exciting because you're making a real difference."
Mr Jones, the company's international business development director, told Radio Wales: "Vaccination programmes are being carried out all over the world in remote areas."
But, he said, vaccines are often stored at the incorrect temperature which can make them ineffective.
"With this technology we're really saving lives and that's the exciting thing."
The fridge uses an energy-storage material and has had to meet World Health Organisation (WHO) standards.
True Energy's Tywyn factory can turn out 5,000 to 10,000 units
Mr Denis Maire, a technical officer in the WHO's department of immunisation, vaccines and biologicals, said it was a unique system not used by any other manufacturer.
"It's new and very interesting because they use a very simple medium which enables the appliance to be very stable in terms of temperature and can keep vaccines for a very long time. It's revolutionary."
Dr Ahmad Faizal Mohd Perdaus is president of Mercy Malaysia, a charity which has received a donation of one of the fridges.
He said: "It is generally known that vaccines are delicate and it is essential that they are stored between 2°C and 8°C, which can be a challenge as external temperatures can influence the instability of the internal temperature of a vaccine fridge.
"We are excited at the prospect of utilising this fridge."
Stewart Jones explained that, after the fridge has been powered up, it can maintain vaccines at temperatures between 2°C and 8°C for long periods of time.
"If power is lost we can maintain those temperatures for up to 10 days, even with temperatures outside of 43°C - and even longer when the temperature is less," he said.
"So at 32°C we can maintain temperatures for up to two weeks with no power at all."
The brains behind this and other True Energy projects is Ian Tansley, and the backer, local businessman Peter Saunders.
"Ian has been working in renewable technologies for something like 25 years. It's a real passion of his," Mr Jones added.
"It's grown from a one-man band, with Ian providing solutions all over the world, to a flourishing business."
The company now employs about 15 people and has just acquired an additional factory unit.
It is also looking at manufacturing partnerships overseas.
"We're in ongoing discussions in India, Africa and the Middle East and the US," said Mr Jones.
Other products the company makes includes solar-powered street lights and water pumps.