The WHO says we waste half the world’s vaccines.

A lot of this comes down to something very basic: temperature.

For the uninitiated, every vaccine dose must remain between 2 and 8°C from the factory until it is administered. Along the way, it passes through multiple hands, storage points, vehicles, facilities, and environments.

Break that range even once, and you may be left with a dose that looks perfectly fine but does nothing.

The problem is that the cold chain was built for a cooler world.

Gavi estimates that only about 10% of health facilities in the world’s poorest countries have reliable electricity. The rest depend on solar, batteries, and generators that were often designed years ago, for very different conditions.

Now those systems are being asked to do more in hotter, harsher environments.

The hotter it gets outside, the more energy it takes to keep vaccines at the same safe temperature.

And in my work across Nigeria, Ghana, and Malawi, the pattern is clear.

The center usually holds.

The edge doesn’t.

National stores and large regional hubs keep getting better infrastructure. But the clinic at the end of the road, the one serving the hardest-to-reach communities, is where the system breaks first.

This is no longer just a medical delivery problem.

It is an energy problem.

A design problem.

A resilience problem.

We need passive cooling that actually works in extreme heat. Better last-mile storage. Off-grid power systems are designed for the climate we are entering, not the one we used to have.

If you’re building, funding, or working on this problem, I’d like to compare notes.