The Food and Drug Administration (FDA) is expected to authorize new COVID-19 booster shots this week. The booster shots will be released months before trials on humans are completed, according to a new report.

New COVID-19 booster shots that target the latest Omicron variant will be approved by the FDA this week, the Wall Street Journal reported. The new booster shot will be "bivalent" – which means it can target the original COVID-19 strain and the Omicron BA.5 subvariant.

The booster shot will likely be available to Americans despite not having been tested on humans. Instead, the FDA will rely on testing on mice, data from current COVID-19 vaccines, and earlier iterations of boosters.

The Wall Street Journal noted, "The Food and Drug Administration is expected to authorize new COVID-19 booster shots this week without a staple of its normal decision-making process: data from a study showing whether the shots were safe and worked in humans."

FDA Commissioner Robert Califf issued a statement on Twitter regarding how the government agency will likely make a decision in granting emergency use authorization (EUA) for booster shots from Moderna and Pfizer.

"FDA will rely on the totality of the available evidence in making a decision, including: Clinical trial data from other bivalent mRNA COVID-19 boosters RWE from current COVID-19 vaccines administered to millions of people, non-clinical data for the bivalent BA.4/5 vaccines, bivalent and multivalent vaccines are very common and modifying a vaccine to include different virus strains often does not require a change in other ingredients," Califf said on Twitter.

Califf compared approving the mRNA booster shots to authorization of the annual flu vaccine.

"Real world evidence from the current mRNA COVID-19 vaccines, which have been administered to millions of individuals, show us that the vaccines are safe," Califf added. "As we know from prior experience, strain changes can be made without affecting safety."

Califf declared that the FDA will not hold a meeting about the newest subvariant-targeting vaccines because the "agency feels confident in the extensive discussion that was held in June."

He said that the Vaccines and Related Biological Products Advisory Committee (VRBPAC) "voted overwhelmingly to include an Omicron component in COVID-19 boosters," and that the FDA "has no new questions that warrant committee input."

In June, two health experts wrote an op-ed urging the FDA not to release the booster shots without proper research. The piece was written by John P. Moore – a virologist and professor of microbiology and immunology at Weill Cornell Medicine – and Paul A. Offit – a pediatrician, professor of pediatrics, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, and a member of the Vaccines and Related Biological Products Advisory Committee.

Offit told the Wall Street Journal, "I'm uncomfortable that we would move forward — that we would give millions or tens of millions of doses to people — based on mouse data."

Moderna has already begun human trials on the booster shots, and Pfizer is expected to begin theirs this month. Experts believe that trials likely wouldn't be completed until the spring.

Earlier this month, White House COVID-19 Response Coordinator Dr. Ashish Jha expected the boosters to be available by "early to mid-September."

Jha also said that the Omicron BA.5 subvariant represents 85% to 90% of all U.S. cases of COVID.

CDC data shows that less than 50% of Americans received the first booster shot, and 33% of Americans over the age of 50 got the second dose.