Originally Posted by Klen

Well , the thing is , scientists cannot agree yet how immune system is working.
First we have claim how immune system work 6 months after first infection.
But then we have cases of re-infection in much less time period.
Then they also says how they checked blood for anti bodies and there was none of it inside, which make it same as you never had it.
Then then say how you should be still be able to defend despite no anti-bodies because immune system recognize it and generate new anti-bodies.
So that is what possibly happened to you.