The 61-year-old singer recently revealed she has antibodies for the respiratory condition and sparked confusion when she was then seen out and about, but she's now explained she actually fell ill some time ago, along with a number of others working on her live show.
Alongside an image of a news article explaining she has donated over $1 million to help find a vaccine, she wrote: "I'm Grateful that I can be a part of supporting Research to Find the cure for Covid -19!!
"And just to clear things up for people who would rather believe sensationalist headlines than do their own research about the nature of this virus--
"I am not currently sick.
"When you test positive for anti-bodies it means you HAD the virus which I. clearly did as I was sick at the end of my tour in Paris over 7 weeks ago along with many other artists in my show but at the time
"We all thought we had a very bad flu. Thank God we are all healthy and well now. Hope that clears things up for the band wagon jumpers!! Knowledge is Power! #covid19 (sic)"
The 'Hung Up' hitmaker revealed she had tested positive for coronavirus antibodies last week when she explained she was looking forward to going out for a "long drive" after weeks in lockdown.
She said: "I took a test the other day. I found out I have the antibodies, so tomorrow I'm just going to go for a long drive in the car.
"I'm going to roll down the window, I'm going to roll down the window and breathe in the COVID-19 air."
In contrast to Madonna's claims, the World Health Organisation has warned there's "no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection".