I’m so old, I remember a few months ago when they told us that having Covid-19 might not give you any immunity at all, because, somehow, it was different this time:

People who recover from mild COVID-19 have bone-marrow cells that can churn out antibodies for decades, although viral variants could dampen some of the protection they offer.

Source: Nature.com: Had COVID? You’ll probably make antibodies for a lifetime

Coldstreams