Additionally, exposure to other corona viruses may provide natural immunity. We know from the Diamond Princess that there was a high level of natural immunity to covid. This should be the mechanism imho.
“The findings ‘support the notion that Covid-19 patients will develop long-term T cell immunity,’ the researchers wrote.
In further experiments, the scientists mixed blood samples with fragments of SARS-CoV-2 to see what happened.
The cells showed ‘robust’ reactivity against SARS-2 in all patients by latching on to them.
To explore the subject of immunity further, 37 volunteers who had never been infected with either SARS-1 or SARS-2 were recruited.
They wanted to see if infection with other human coronaviruses that have been around for centuries offered some kind of protection against Covid-19.
The researchers found ‘remarkable’ levels of T cells able to latch on to the Covid-19 virus in 50 per cent (19) of the participants.
‘Surprisingly, we also frequently detected SARS-CoV-2 specific T cells in individuals with no history of SARS, Covid-19 or contact with SARS/Covid-19 patients,’ the authors wrote. “
Sure, but we don’t understand T-cell immunity and how protective it is. B cell immunity is very strong, but T-cell may permit reinfection.
B-Cell is every cop on the look-out for a subject. T-cell is a wanted poster on a forgotten bill board at the back of the police station. It provides some record, but not the same protection.
Just today we have the story of the congressman in bad shape with a Covid reinfection:
https://www.foxnews.com/politics/republican-congressman-covid-19-second-time