What is immunity debt and could it explain outbreaks?

You've probably heard of Omicron, but what about Nimbus and Stratus? These are the latest COVID strains spreading around the world, and for most people they'll amount to a heavy cold at worst, lasting just a few days. Or will they? Are these coronaviruses doing more to our immune systems than meets the eye? Like this podcast? Please help us by supporting the Naked Scientists