Do you think we really need a vaccine? Why is no one talking about how to improve your immune system?

People with strong immune system often have worse reaction to virus because in many cases it's not the virus itself causing complications, it's the immune system going haywire trying to kill the virus. There's a common belief that regular exposure to cold strengthens your immune system so some people deliberately do activities such as swimming in icy ponds during the winter. Sadly, it turned out that those were the ones with far worse symptoms than other people. 🙁 Same with people who actively do sports and keep themselves in good physical condition.