Here's what makes the increase in BA.5 cases different from previous COVID-19 surges

LOS ANGELES (KABC) -- With the highly-infectious and immune-evasive BA.5 subvariant spreading rapidly, there's a renewed push to get people vaccinated and boosted.

A new CDC study finds among those 50 and older, those unvaccinated are 29 times more likely to die from COVID-19 than those fully-vaccinated and double-boosted.

"If you haven't gotten a shot in the last six months or in the year 2022, you need to get one now. It will protect you for the rest of the summer into the fall," said Dr. Ashish Jha, the White House COVID response coordinator.

Genomics researcher Dr. Jasmine Plummer with Cedars-Sinai says the BA.5 variant is more transmissible because it contains spike protein mutations that prevent antibodies from neutralizing it.

"It has additional mutations that probably allow the virus itself to replicate faster," she said.

But by the time vaccines targeting BA.5 arrive this fall, a different subvariant could be dominating. One possible threat is BA.2.75. Like its predecessor, this new subvariant contains even more spike protein mutations

And it can also efficiently make more copies of itself. Yet, Plummer said it's not yet known how BA.2.75 disease severity compares to other subvariants.

"It could be another variant like what happened last summer. We had a variant that came up and then went back down over the summer," Plummer said.

"If you wear a good mask, an N95 or a KN95, a mask that is well-fitted, it will protect you from being infected," said Dr. Anthony Fauci, the White House chief medical advisor.

And starting Monday, University of California Irvine resumes its indoor mask policy on campus, making mask-wearing mandatory in all indoor spaces. The same at UCLA, with daily symptom monitoring also in effect.

Fauci adds a well-fitted medical or respirator mask will protect others as well.

"And if you are infected and asymptomatic, it would help in preventing you from spreading infection," he said.

Fauci said active discussions are underway about whether the FDA will authorize a second booster vaccine for Americans under 50 years old. He said we should expect an answer soon.