As others note it's super complicated with viruses. If you want to track the mutations in real time, check out the Nextstrain project (https://nextstrain.org/). The main person behind it, Trevor Bedford, is also a good person to follow on twitter for these topics and had a brief thread on mutation rate and immunity. (https://twitter.com/trvrb/status/1244750382338719745?s=20) TLDR: Though there's some uncertainty, given what we know today, it doesn't appear to be mutating in a way that will substantially affect immunity or morbidity.