(NewsNation Now) — A preprint study published Wednesday showed that the antibodies in blood samples from recipients of two Moderna doses were less effective at neutralizing the omicron variant, suggesting an increased risk of symptomatic breakthrough cases. Moderna’s chief medical officer joined “Morning in America” to clarify the findings.

“What we know about omicron is that it has numerous mutations, many of them in the spike protein. It’s not surprising that the vaccines don’t act against omicron as effectively as they did against delta or the original strain,” said Dr. Paul Burton.

The preliminary research, which has not yet been peer-reviewed, analyzed blood samples from 30 participants fully vaccinated with two Moderna doses. Researchers tested antibodies in the blood with “pseudovirus” versions of the omicron strain at the National Institutes of Health and Duke University laboratories.

They found these antibodies in two-dose Moderna recipients were at least 50 times less effective at neutralizing the omicron strain, which “could lead to an increased risk of symptomatic breakthrough infections.”

“What we’re seeing is if you get the booster shot of the Moderna vaccine you will increase the levels of antibody and that will likely give you some protection,” Burton said.

The seven participants who received a Moderna booster saw an about 12-fold improvement in the neutralization against the omicron variant, which researchers noted “may substantially reduce the risk” of COVID-19.

Data from South Africa also found that two doses of the Pfizer-BioNTech vaccine were only 33 percent effective at preventing omicron infection, although it was still 70 percent effective against hospitalization. 

Top infectious disease expert Dr. Anthony Fauci cited the preliminary data on the effectiveness of mRNA boosters when saying there’s no need for a vaccine designed specifically to combat the omicron variant yet.

“Our booster vaccine regimens work against omicron,” Fauci said at a Wednesday briefing. “At this point there is no need for a variant-specific booster.”

Slightly more than a quarter of the U.S. population has received their booster dose, according to Centers for Disease Control and Prevention (CDC) data.

“Dr. Fauci’s comments are correct. If people are on the fence get vaccinated. if they are thinking about getting a booster shot there’s never been a better time,” Burton said. “We’re leaders in this field and mRNA technology. It’s on us. We have to be prepared if it is the dominant strain.”

Scientists raised concerns about the omicron variant first reported in South Africa and Botswana in late November due to its high number of mutations, and early data indicates it’s more transmissible than the delta variant and doubling every two days.

At least 36 states and 75 countries have identified omicron cases. The CDC estimates that the strain makes up 3 percent of cases in the U.S., with higher rates in areas like New York and New Jersey.

Burton says the strain is “highly transmissible.”

“People who get infected with delta strain of COVID typically don’t get reinfected. What we’re seeing with omicron is information that those people can get reinfected. So omicron doesn’t respect prior infection,” he said.

The Hill contributed to this report.