The first, big statements made in the media around coronavirus vaccines and herd immunity – I read and listened and scratched my head. After all, there’s not been a successful coronavirus vaccine made so far. This is the same family too which give us the common cold. Over 200 versions of the virus makes herd immunity difficult.

The whole situation seemed odd to me. As odd as lockdowns, supermarket closures, no commercial flights and a ton of empty cruise ships sitting off the coast. Don’t get me wrong. I’m partial to the environmental benefits. Just the virus and our body’s response to it – and the way it was being talked about – was a mystery.

My eureka moment came late. It wasn’t until I left the screams of the media and did the basic reading. I realised there is no herd immunity with coronavirus. Not the classical, humoral one anyhow.

I read there are so many varieties of coronavirus, we fight this virus mostly with our ‘brawler’ immune cells, our T cells. They don’t go off to have sophisticated meetings like our herd-y B-cells do. And if scientists do come up with a vaccine for this viral strain, which I’m not saying they won’t, will likely be a T-cell-led vaccine. Which will be revolutionary for medicine. Digits crossed.

The immune system is surely an amazing thing. It’s kept us alive for all our species’ time on this planet. It’s fought against an army of crawling, slimy, cunning pathogens. And this leads me to coral. I’ve got coral on the brain now too. And a sore shoulder from cleaning nursery coral trees yesterday. That’s ok though. I think I just need to get fitter.

Sometimes our immune system comes at a cost. Replacing organs without rejection means dampening the immune system with large amounts of steroids. The same applies to the slew of auto-immune diseases, when the immune system treats its own body as though it’s an outside threat. It makes me think of stealing your own jewellery. Or calling the police when finding your own shopping in the house. It doesn’t make much sense.

Coral has had to live with this trade-off too. Even though it’s one of the oldest animals on the planet, scientists are finding some corals have relatively sophisticated immune systems. More sophisticated even than the organisms which evolved after them.

Perhaps there’s a reason. One of the key things coral has had to learn for example, is not to reject the algae which live inside of it. Corals share their space – and both organisms benefit. This symbiosis; the algae receiving a place to live in the coral’s stony home while the algae feeds the coral with sugars it makes through photosynthesis. It’s a simple arrangement on the outside. It requires trickery though. It requires the coral’s immune system not to reject it. In this way it isn’t simple at all. A bit like this coronavirus thing. Not so simple.