Laying out its strategy to manage BA.5 ahead of a 9.30am briefing with top public health officials, the White House said there were indications the sub-variant might be better at escaping immunity, including from prior infections.

Officials will prioritise getting Americans booster shots, making at-home testing and high-quality masks widely available and supporting people who are immunocompromised.

“These tools – even in the face of BA.5 – work to prevent serious illness, keep people out of the hospital, and save lives – and we can prevent nearly all Covid-19 deaths with them,” the White House said in a statement.

The BA.5 and BA.4 sub-variants now make up 80% of Covid-19 cases nationwide, with BA.5 accounting for a majority of cases, the White House added.

The White House said BA.5’s wide circulation means new cases would likely rise in the coming weeks.

“This potential for increase is greatest where fewer people are up to date on their vaccinations and there is increased waning of immunity from vaccines,” it said.

The US Food and Drug Administration has recommended Covid-19 vaccine manufacturers change the design of their booster shots from the fall to better combat the BA.4 and BA.5 sub-variants.