"At the end of May there was a significant breakthrough in understanding of COVID antibodies which was not widely reported: a Swiss study from Zurich led by Professor Onur Boyman74 demonstrated that a large proportion of the population had a natural immunity through existing antibodies on the mucous membrane (IgA) or cellular immunity (T cells), likely to have been acquired through previous exposure to coronaviruses such as influenza or the common cold.

This explained why, by July, the virus had all but disappeared in populations like Sweden, New York (Fig. 7) and Wuhan (which reportedly tested its entire population of 11 million and found only 300 cases, all of which were asymptomatic)81 which were significantly affected by a “first wave”: if the ratio of those with IgA and T cell antibodies to IgG and IgM antibodies across population was confirmed at a factor of five then if 20% of the population had traditional IgG and IgM antibodies (such as New York with 21% and London with 17%82) then the virus died out because there was simply no one left for it to infect. It followed that the virus could only survive in population samples where testing showed the presence of IgG and IgM antibodies was below 20% (and allowing for their decay probably well below).

Nobel Prize winning biological scientist Michael Levitt had already come to the same conclusion based on a different approach: he predicted that the virus would “burn out” when it had infected 15-20% of the population though based on a pattern predicted by the “Gompertz curve”83 which indicated that the number of deaths after the peak is roughly double those from before84 resulting in Levitt accurately predicting the number of Chinese85 and Swedish deaths86months in advance 87. Levitt has recently bravely predicted that US COVID will “be done in 4 weeks [25 Aug] with a total reported death below 170,000”88, compared to 149,000 today89.

Boyman’s theory on “IgA and T Cell immunity” explained the accuracy of Levitt’s “Gompertz curve” predictions and this was now being backed up by the empirical evidence which showed that the populations which were hit hardest with high initial rates of infection and mortality, were the ones where the virus had almost disappeared. "