The below was a study done in Australia. It shows that the range of antibody neutralisation reactions varies depending on how severe an illness the patient had and which variant. Some affect the neutralising capabilities, others don't, but they figure that a good response in the right patient, with the right variant and severity, could last quite a while.Plos Article
Increasingly, they are finding that having Covid 19 does not necessarily bestow immunity. There is at least one KAer that has had it twice, and that person had been vaccinated prior to the second infection. But he's a KAer, so has other medical considerations. Still, they have been looking at this increasingly due to the hope that Covid Antibodies could form an effective defense and to understand whether immunity is possible.
Here's an article from JAMA analysing work on natural antibodies protection is boosted after Pfizer or Moderna.JAMA Analysis
I don't often use news media, but this is a good write up and you should be able to find the actual study through it. Independent Article
You make your own decisions as to the vaccine and its efficacy. I have seen both sides of the research and know that as an immune compromised patient, they are the way to go if I want any kind of a life at all, during this. Especially with so many running around without any care at all for the fact that they are prolonging this with their actions/inactions.
As to Dr Peter McCullough, is he the guy claiming to cure Covid with Ivermectin? I don't think much of him. For many reasons I don't care to go into, here.
For truly good analysis of what's going on overall, look for Your Local Epidemiologist