The White House COVID-19 response team doesn't believe it's a good idea for people to wait for a modified version of the vaccine that targets the omicron variant.

Health officials said they are concerned about waning immunity as the omicron subvariants, BA.4 and BA.5, rapidly spread across the U.S.

"My message is simple: It is essential that these Americans get their second booster shot right away," said Centers For Disease Control Director Dr. Rochelle Walensky.

The subvariants now make up 80% of new cases in the country, according to the Centers for Disease Control.

“We are experiencing about 300-350 deaths a day," said White House COVID-19 czar Ashish Jha. "That is unacceptable. It’s too high."

Currently, people 50 and older are eligible for a second booster shot. Some people ages 12 years and older who are moderately or severely immunocompromised can also get a second booster. However, Walensky noted that a large portion of the population has still not got their first booster shot.

While a vaccine that targets the omicron variant is expected in the fall, Walensky said the threat is now. The response team noted that getting a booster now wouldn't make a person ineligible for an omicron-specific vaccine in the fall or winter.

In addition to making sure a person is up to date on their vaccinations, health officials said people should consider masking when they are in an indoor public space.