Yet this doesn't mean anything as they didn't study T-cell response, and many other things.
It is absolutely ridiculous fearmongering, and clickbait, by a top university + the press.
As far as I know there has been 1 reinfection case in the entire US, and that was questionable as the guy tested positive the second time a few days after testing negative, so its possible it was a false positive. 1 case, in the ENTIRE US. It is ridiculous to suggest there isn't some sort of immunity. The virus has been around for 9 months now.