Joe Biden likely infected by highly contagious BA.5 subvariant

President Biden’s coronavirus likely stemmed from the Omicron subvariant BA.5, currently the most dominant strain of the virus in the U.S., according to a letter from the White House physician on Saturday.

The big picture: BA.5 is responsible for 75-80% of infections in the U.S., his physician Kevin O’Connor said in a letter on Saturday.

• BA.5 is so transmissible — and different enough from previous versions — that even those with immunity from prior Omicron infections may not have to wait long before falling ill again, Axios’ Tina Reed writes.
• A new study found that BA.5 is four times as resistant to vaccines as previous strains. The president is fully vaccinated and received a second booster shot in March.

Details: Biden, who tested positive for COVID on Thursday, had his virus sample sent for sequencing to determine what variant he has, Ashish Jha, the White House’s COVID-19 response coordinator, said at a briefing that same day.

• It’s not clear where exactly Biden was infected, Jha added.
• Biden’s symptoms continued to improve after his first full day of Paxlovid.

What they’re saying: “This data does not affect the treatment plan in any way,” O’Connor said.

• Biden completed his second day of Paxlovid treatment and his symptoms are improving O’Connor added.
• “The President is responding to therapy as expected. The BA5 variant is particularly transmissible and he will continue to isolate in accordance with Centers for Disease Control and Prevention recommendations.”

Go Deeper: The summer of subvariants