It's your own opinion... but maybe you should stop comparing SARS-CoV-2 to dengue fever or tetanus then.
Well you started by providing a generic document that only talks about immunity in general. It was not aimed at Covid, so I provided a response that was similarly based. Like I said it was poorly written so if it was aimed at covid immune responses it definitely does not say so.
There's some interesting stat anomalies in the middle east, with UAE stating 750,000 cases and only 2000 deaths, yet next door in Yemen it's 9000 cases for 1700 deaths. UAE death rate seems incredibly low for the case numbers, similar to Kuwait, then Saudi and Iraq have normal rates comparable to other nations. The UAE stands out as something is wrong in the recording of cases or deaths, maybe there is some 'natural immunity' happening.