The question I get more than any other:
“I had Covid. I had an antibody test to prove it. Am I protected (and do I need to get the vaccine)?”
Let me start with the usual disclaimer: THIS IS NOT MEDICAL ADVICE. I AM NOT A PHYSICIAN.
But the answer is now increasingly clear: natural immunity from Covid following infection and recovery is HIGHLY protective against future Covid infections. Rates of reinfection are very low.
Perhaps natural immunity eventually wanes, but we don’t know when. In fact, a little-noticed paper from June suggests it may actually strengthen for at least a year – and provide plenty of protection from Delta and other variants.
I am not going into the problems with vaccine-generated protection today or with our political unwillingness to recognize natural immunity. (Remember, GOOD NEWS – we could all use it).
Let’s just look instead at why natural immunity works so well.
You immune response comes in two forms: “humoral” and “cellular.”
When you are infected with Sars-Cov-2, your body’s “B-cells” – part of the immune system – quickly pour out “antibodies.” These antibodies attack the viral particles circulating in your blood and other fluids, hoping to keep the virus from entering your cells and replicating itself.
This is humoral immunity. Your B-cells make antibodies in many different shapes. Some are better at sticking to the virus. Scientists call these “neutralizing” antibodies because they neutralize the “antigen,” the foreign body attacking you, keeping it from entering your cells.
Amazingly, your B-cells quickly figure out which antibodies neutralize most effectively and make more of them, while cutting back on those that don’t work.
At the same time, another part of the immune system – killer or CD8 T-cells – attacks cells that the virus has already infected. You destroy your own cells to prevent the virus from using them to make more copies of itself. This is cellular immunity.
For a few days after you are infected, your immune system is in a race with the virus. If you win the race, defeat the virus, and recover – as the vast majority of people infected with Sars-Cov-2 do – within a week or two you should have no measurable levels of virus in your body.