US President Joe Biden has tested negative for Covid-19. He has been in isolation since he tested positive again on July 30.

A report by the physician to the president was posted on the White House's website on Saturday. It says Biden is feeling well.

But the physician stated in the report that the president will continue "his strict isolation measures pending a second negative test."

Biden first tested positive on July 21. He tested negative six days later and came out of isolation.

The president went back into isolation, after he tested positive again on July 30.

Biden was treated with an antiviral medicine developed by Pfizer, when he first tested positive.

His doctor said in a previous statement that the treatment can lead to rebound cases in a small percentage of patients. He said Biden's positive test on July 30 "represents 'rebound' positivity."