I'm not sure what exactly you think is negative? The claim that infections top out at 10-20% is clearly not true. Even if it were true, we don't really know enough yet to conclude that T-cells would be the reason why.

> It’s a tough hypothesis to completely verify but the dip in deaths and infections in many places in spite of lifting lockdowns lends some support to this theory.

This sounds like a pretty weak correlation to be honest. Just because a lockdown is officially lifted doesn't mean everyone suddenly reverts to their old behaviors.

It isn't true _everywhere_. It might be true in some places. For example, towns with young residents and lots of children. Or suburbia where there isn't much incidental contact with others for long periods of time.

The goal here, in my opinion, is to _never_ return to the sort of broad stroke lockdown where society stops completely. That is an entirely untenable solution, and any new evidence we have to mitigate the virus without that sort of action is welcome news. We should be cheering these researches on, not vilifying them. They are doing science. It is an imperfect art, it is a series of terrible mistakes that eventually lead to a revelatory moment.

> This sounds like a pretty weak correlation to be honest. Just because a lockdown is officially lifted doesn't mean everyone suddenly reverts to their old behaviors.

The behavior changes vs. policy changes is interesting. Estimates of Rt were falling before the lockdowns and continued falling at about the same rate without any apparent discontinuity through the intervention.

It makes one wonder how effective the policy measures really were-- if they were effective vs. what the population did voluntarily vs. any inherent effects from the structure of the contact network, you'd expect to be able to see some effect in a time series.

No one claimed infections "top out" at 10-20 %. I agree, that is CLEARLY untrue. Rather, they seem to "level off" at 10-20%. That is, the rate of spread/new infections stops increasing so fast. Exponential infections always follow an S curve, but usually the leveling off of new infections starts at much higher penetration levels (e.g., 50%).

I mean, perhaps I misinterpreted the original article, but it sure sounded like the author was hypothesizing that T-cells confer immunity to a large percentage of the population which is why we were only seeing infection rates of up to 10-20% in the wild. I'm not sure his theory would make much sense if he actually meant "the rate of spread stops increasing so fast after 10-20% but continues up to 60% anyway".

Your confusion seems to lie in the implicit assumption that the "immune" can never get infected. That's not how immunity works, in general. Immunity is a level of protection not an infallible shield.