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Dr. Fauci says Covid vaccines can be easily adapted to new variants, drugmakers working on boosters

Pfizer and Moderna‘s current Covid-19 vaccines can be easily adapted to target new strains of the virus, something the drugmakers are already working on, White House health advisor Dr. Anthony Fauci said Wednesday.

New strains of the coronavirus have emerged in the United Kingdom, South Africa and Brazil that have given scientists some cause for concern. Although it’s no surprise the virus is mutating, researchers are quickly trying to determine what the changes might mean for recently developed lifesaving vaccines and treatments against the disease.

Some early findings published in the preprint server bioRxiv, which have yet to be peer reviewed, indicate that the variant identified in South Africa, what scientists are calling the B.1.351 strain, can evade the antibodies provided by some coronavirus treatments and may reduce the effectiveness of the current line of available vaccines. Fauci told CNN in an interview that it was very similar to the new strain found in Brazil.

However, there is some good news: The newly developed mRNA technology used to make the vaccines from Pfizer and Moderna makes it easy to adapt to the new strains, Fauci said. He added that the drugmakers are already working to make so-called “booster” shots that will target the variant found in South Africa, which appears to be more problematic than the others.

“We’re already trying to stay one or two steps ahead of the game so that if, in fact, we have a situation where the South African strain is prevalent here — it’s here, but it’s certainly not dominant — you want to really get ahead of it from a protection standpoint,” Fauci said. “You’re going to want to have a vaccine that specifically addresses that strain.”

Earlier on Wednesday, Fauci, director of the National Institute of Allergy and Infectious Diseases, said federal agencies would collaborate to study how effective Covid-19 vaccines are against mutated strains of the virus. While the authorized remain highly effective against the B.1.1.7 strain first identified in the U.K., “things get a bit more problematic” with the B.1.351 strain.

Even then, both vaccines have proven to be about 95% effective in preventing Covid-19 in clinical trials, allowing a little bit of cushion where the vaccines will still work even if any of the variants reduces their effectiveness, the infectious disease expert has said.

Testing the effectiveness of the booster vaccines doesn’t require starting from scratch, Fauci said. The booster shots won’t need to go through the same large-scale clinical trials that were required for the original vaccines to receive the U.S. Food and Drug Administration’s emergency use authorization in December, he said, adding that they could get through with a “quick phase one” trial instead.

“You don’t have to do a 30,000 person trial or a 40,000 person trial,” Fauci said. “You work with the FDA and you could bridge information from one trial to another. Bottom line is we’re already on it.”

Moderna announced Monday that its Covid-19 vaccine might be less effective against the B.1.351 strain in South Africa, and that the company is accelerating work on a booster shot to guard against that variant “out of an abundance of caution.”

Pfizer said on Tuesday that the company, along with German drugmaker BioNTech, would also develop a booster shot, according to a Reuters report citing an email from the company.

A spokesperson for Pfizer told CNBC that the company published a study on Wednesday, which has yet to be peer reviewed, that found their vaccine was still effective against lab-engineered mutations seen in the new strains found in the U.K. and South Africa.

The mutations seen in the variant found in South Africa did have a small impact, but they are still “unlikely to lead to a significant reduction in the effectiveness of the vaccine.”

“While these findings do not indicate the need for a new vaccine to address the emerging variants, the Companies are prepared to respond if a variant of SARS-CoV-2 demonstrates evidence of escaping immunity by the COVID-19 vaccine,” the statement said.

It was not clear when the study was posted and whether Pfizer-BioNTech will be making a booster.

— CNBC’s Will Feuer and Berkeley Lovelace Jr. contributed to this report.