LOL...from your article....
“Indeed, a population sero-prevalence study in 133 Brazilian cities including Manaus found a much smaller (∼20%) sero-prevalence in July-August, 2020. Hence, the blood donor data in Manaus are most likely biased and/or their analyses are flawed”
From the CDC website...
“A positive test result shows you may have antibodies from an infection with the virus that causes COVID-19. However, there is a chance that a positive result means you have antibodies from an infection with a different virus from the same family of viruses (called coronaviruses).”
I actually believed you were serious.
How can you possibly believe that someone can be re-infected by a “variant” but can’t be re-infected with Covid after SARS?
In all three of those articles there is a whole bunch of guessing, inferring, extrapolating, etc....but not once does it show an example of someone getting sick, testing positive for COVID, recovering, getting sick again and testing positive again. You would think they could at least find one example in that town to mention in the articles.
Whatever is going on, there is something seriously amiss in South America: Several countries (per Worldometers) have come off high case peaks, but instead of a protracted drop following, in some there has been only a slight drop and then a leveling off of cases. In Brazil, at least temporarily the fatalities are still dropping (too soon to tell?) but in say, Argentina, fatalities are still rising, and in Colombia they are maintaining at essentially peak level. :-(
I never made that claim. Changes to the antigens of a pathogen (i.e. antigenic shift and antigenic drift) result in a diminished immune response. Hence why Influenza is a problem year after year even in people who've had the flu many times. This applies to any pathogen where antigens drift and/or shift. SARS-CoV-2 is no exception.
The number of people who actually had SARS2003 (7,322 worldwide) or MERS2012 (1,684 worldwide) is so vanishingly small that it would be difficult to accurately determine whether they have any immunity to SARS-CoV-2 without challenge trials. That would be unethical to do, particularly given the risks of ADE with the SARS-CoV-1 nucleocapsid protein antibodies. That's why those proteins were not targeted in any of the COVID-19 vaccines.