One of the treatments available for people with severe allergies is “desensitisation”, which involves repeated injection of small amounts of the offending antigen.
There have been numerous anecdotal reports of people experiencing frequent episodes of Covid-19 infection, whether or not vaccinated, and there is still no good explanation for why this is happening and whether there are any particular characteristics which predispose to reinfections.
There was never any reason to expect that “natural immunity” – the protection acquired through infection to SARS-COV-2 – should not be similar to that acquired for other respiratory viruses humankind has come into contact with – robust, flexible and durable. Were it not, our species would have been wiped out many millennia ago.
Evidence is now emerging that natural immunity to SARS Cov-2 from previous infection is as good if not better than any of the current genetic therapy vaccines. Indeed, previous infection by SARS Cov-2 creates a very robust immune response which is effective against many variants.