Was New COVID Vaccine Booster Tested on Only 8 Mice? What We Know

According to the Food and Drug Administration, the new COVID-19 vaccine booster was tested on only eight mice.

Due to the fact that clinical trials were conducted on mice rather than humans, new COVID boosters that will be ready by the end of the week are being scrutinized.

The Food and Drug Administration (FDA) on Monday approved the boosters produced by Pfizer-BioNTech and Moderna. Due to concerns about a rise in respiratory diseases across the country this fall and winter, a panel of advisors to the Centers for Disease Control and Prevention (CDC) voted 13-1 in favor of its widespread use for people 6 months and older on Tuesday.

Depending on the locale, the new vaccines will be offered at local pharmacies, physicians’ offices, and public health departments in addition to large pharmacies like CVS and Walgreens.

Some have questioned the efficacy of these revised boosters because they will be the first to be made available to the public without involving any humans in the clinical trials.

To combat the then-dominant XBB.1.5 subvariant, the FDA asked manufacturers to create a new booster in June. The BA.5 omicron subvariant is combated by the new bivalent shots.

An FDA representative declined to respond to a particular question from Newsweek regarding the testing procedures, saying that Pfizer and Moderna could provide more information about their procedures.

The FDA press release, which claims that the revised mRNA vaccines are produced using a comparable procedure to earlier formulations, was referenced by the spokesman.

“In studies that have been recently conducted, the extent of neutralization observed by the updated vaccines against currently circulating viral variants causing COVID-19, including EG.5 and BA.2.86, appears to be of a similar magnitude to the extent of neutralization observed with prior versions of the vaccines against corresponding prior variants against which they had been developed to provide protection,” the release says.

“This suggests that the vaccines are a good match for protecting against the currently circulating COVID-19 variants.”

According to previously authorized and recommended immunizations, it also states that “the benefit-risk profile is favorable” for people aged six months and older who are advised to obtain these boosters.

In a statement, CDC Director Mandy Cohen stated, “We have more tools than ever to prevent the worst outcomes from COVID-19.”

In an opinion piece that appeared in the New York Times on Wednesday, Cohen acknowledged that coronavirus is likely to always be around, but that serious illnesses, hospitalizations, fatalities, and long-term effects can and should diminish thanks to new scientific advancements that can also help people fight off flu and respiratory syncytial virus (RSV) infections.

“Some viruses, however, change over time,” she said. “This coronavirus is one of them. It finds ways to evade our immune systems by constantly evolving. That’s why our vaccines need to be updated to match the changed virus. Even though many Americans have been exposed to previous versions of the virus because they’ve been infected, that protection decreases over time.”

Since 2021, more than 670 million doses have been given in the United States.

In an episode of her podcast, “The Megyn Kelly Show,” that aired on September 6, Megyn Kelly confessed she regretted getting the COVID shot due to a vaccine injury.

Infectious disease specialist Dr. David Wohl of the University of North Carolina School of Medicine told Newsweek via email that the safety of the COVID-19 vaccines, even in children, has been closely monitored.

“With so many people across the world having been vaccinated, often repeatedly, there are large data sets that allow for detection of safety signals,” Wohl said. “We saw how with the Johnson & Johnson vaccine, those signals led to a preference for the Pfizer and Moderna vaccines.

“I am confident that these vaccines are safe, including for kids. I am much more concerned about the side effects of COVID-19 than the vaccines.”

The ‘Mouse Test’

On August 25, FDA Commissioner Dr. Robert Califf stated on X, formerly Twitter, that the new boosters were developed using clinical trial data from other bivalent mRNA COVID-19 boosters.

“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 wrote. “FDA has extensive experience with reviewing strain changes in vaccines, as is done with the annual flu vaccine.”

Pfizer performed preliminary studies on eight mice in June 2022. Uncertainty exists on the precise number of mice used in the current research.

Data provided by Pfizer to the CDC on Tuesday showed that in trials involving female mice, 10 per group, a primary series of monovalent vaccine was administered, followed by a third booster dose of the bivalent vaccine (original vaccine plus BA.4/5) and a fourth booster dose of either a bivalent (original plus BA.4/5) or a monovalent (XBB.1.5) vaccine.

These updated boosters, according to Wohl, use the same methodology and technology as the earlier shots “and only tweak the text of the message they send to our cells so that they make a COVID-19 spike protein that looks more like the variant circulating now.”

“Variants have been emerging every few months as we continue to transmit the virus to each other, therefore clinical trials of each updated vaccine is not practical or helpful since by the time the results would be available newer variants would likely be circulating,” he said.

According to John Moore, an immunologist at Weill Cornell Medicine, using “mouse data” is more of a concern for effectiveness on people than for safety.

“For the FDA to rely on mouse data is just bizarre, in my opinion,” Moore said. “Mouse data are not going to be predictive in any way of what you would see in humans.”

Moore said to Newsweek via email on Thursday that his comments were made about a current debate (in 2022) regarding whether vaccination effectiveness in mice can be predicted.

“I would not have said the same words this time around, as the context is different (as is the extent of our knowledge on booster composition changes),” he said.

Wohl echoed Califf’s argument that vaccines unrelated to coronavirus and SARS-CoV-2 have gone through similar clinical studies, saying that such testing is standard procedure.

“We have a similar challenge with influenza,” he said. “And every year the flu shot is tweaked to better match what is coming our way. Some years the match is good, others less so.

“With the mRNA technology that has been so successfully used for COVID-19 vaccines, we may be able to shorten the time to develop flu shots and therefore better match the flu virus that will arrive each flu season.”

Questions surround both the safety and efficacy of these new boosters in the post-pandemic era, where confidence in COVID-related vaccinations is probably lower than it was when they were originally made available.

“There’s no reason to think they’ll be unsafe,” Dr. Celine Gounder, an infectious disease specialist at NYU Langone Health in New York City, told NBC News. “But whether they provide significantly more protection than the original vaccines? Of that I’m skeptical.”

All eligible individuals have been urged by President Joe Biden to get the booster to “protect those around you this fall and winter.”

But the skeptics continue.

“The latest and greatest version of the Covid vaccine was tested on 4 rats, which oddly died peacefully of natural causes in their little cages!” wrote one user on X. “If the FDA says it’s good to go, what could go wrong?”

Everyone eventually has to decide whether to get vaccinated, according to Wohl. He is particularly pleased by the fact that older Americans have been the age group most ready to receive a coronavirus vaccination, which he attributes to their experience and awareness of the risks involved.

“These decisions should be based on facts and not lies or nonsense,” Wohl said. “Unfortunately, the assault on truth that has been undertaken to cast doubt and discord, has shaken confidence in what had been respected and unassailable sources of information and advice. This has been almost as deadly as the COVID-19 virus.

“Leadership matters and when those to whom we give this responsibility point the way to what evidence tells us keeps us safe, rather than being amplifiers of our fears, we benefit. When they don’t, we suffer.”