Washington, Aug 4 : US President Joe Biden is "still experiencing an occasional cough" after he tested positive for Covid-19 in a rebound case, his physician has said. The symptom is less frequent than a day earlier, White House physician Dr. Kevin O'Connor wrote in an update on WEdnesday about Biden's recovery. Fever-free, Biden "continues to feel well" and finished a light workout in the morning but his antigen testing remained positive, Xinhua news agency quoted O'Connor as saying. Biden, 79, tweeted on Wednesday that he had held a secure phone call with his national security team, alongside a picture of him wearing a mask and sitting behind a desk. The President had tested positive for Covid-19 on July 21, and was negative on July 26 after days of isolation and treatment. He tested positive again on July 30 in the "rebound" case, according to the White House. /IANS