Washington DC - The Biden administration is warning Americans to take the latest Covid-19 variant, BA.5, more seriously, but its strategy is to keep doing more of the same – encouraging masking, testing, and getting vaccinated when applicable.

The BA.5 variant now makes up more than half of all cases in the United States, and the BA.4 variant makes up roughly 20%. The two new Omicron subvariants are much more transmissible than earlier omicron subvariants, and, unlike previous variants, can evade natural immunity.

Scientists don't yet know how sick BA.4 and BA.5 are making people compared to other Omicron strains, CDC Director Rochelle Walensky said during a briefing Tuesday. But they do know it’s much more transmissible. Even those previously infected by other omicron subvariants do not have much protection against these new variants.

The good news is that current antivirals also work to treat these subvariants. Covid-19 vaccines work to prevent infection in these variants as much as they do for other omicron subvariants.

Top public health officials said they are having active conversations about making second booster doses available to all adults, but the final decision will fall on the decision-makers at the FDA and CDC. Second boosters are currently available only to those ages 50 and up.

Shots that protect against Omicron specifically should be ready in early October, said White House Covid-19 Response Coordinator Ashish Jha. But if an individual receives a second booster this summer, that doesn’t bar them from getting another shot in the fall.

Speaking of vaccines, the bad news is that many older Americans are unprotected, Walensky said. Only 28% of people older than 50 have received a second booster shot.

CDC data shows those older than 50 with only one booster are four times more at risk of dying from the virus compared to those who have two booster shots, she said.

Right now, the US is seeing about 5,100 Covid-related hospitalizations per day, a doubling since early May, and about 350 deaths per day, according to Walensky. About 32% of the country is living in an area with high transmission of the disease, per CDC data.

Even though the new variant is spreading rapidly, public health officials repeatedly said the country is able to handle this moment in the pandemic. Jha encouraged Americans to wear masks in crowded indoor spaces and to take a test before attending a large gathering, such as a wedding or visiting a high-risk person, like a grandparent.

"We’re at a point in the pandemic where most Covid-19 deaths are preventable," Jha said.