US President Joe Biden's ­COVID-19 symptoms "continue to improve" and he is tolerating treatment well, his White House physician said Saturday, two days after the 79-year-old tested positive for the virus.

Biden, who is isolating at the White House, completed a second full day of Paxlovid on Friday night, his doctor Kevin O'Connor wrote in a memorandum to the White House press secretary.

The US leader continues to experience a sore throat, runny nose, cough and body aches, but they are "less troublesome." 

And his pulse, blood pressure, respiratory rate and temperature "remain entirely normal." His oxygen saturation "continues to be excellent on room air," while his lungs are "clear," according to O'Connor.

He wrote that Biden will continue to take Paxlovid, as well as using Tylenol and an inhaler for his cough "as needed." The president "is experiencing no shortness of breath at all," O'Connor added.

He said that primary sequencing results showed Biden most likely had contracted the highly transmissible Omicron BA.5 subvariant.

While Biden is reported to be in good general health, as the oldest US president ever elected his age heightens concern over the impact of ­COVID-19 .

The White House has emphasized since Biden's diagnosis that the president was fully vaccinated and twice boosted.

O'Connor reiterated that the president will keep isolating in accordance with guidelines from the US Centers for Disease Control and Prevention, and that his team will continue monitoring him "closely."