Vaccines May Not Be as Effective Against Variants, Fauci Says

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The current COVID-19 vaccines may not be as effective against new coronavirus variants, but they should be powerful enough to still be beneficial, Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, said during a news briefing on Thursday.

Both vaccines from Pfizer-BioNTech and Moderna have such high efficacy rates that it creates a "cushion effect," he said, meaning that new variants will likely only diminish vaccine efficacy slightly. To slow the spread of the new strains, Fauci said, people should get vaccinated as soon as possible. If viruses can't spread as far or as quickly, they won't mutate as much.

"Bottom line: We're paying very close attention to it," he said. "There are alternative plans if we ever have to modify the vaccine."

The U.S. has reported 144 cases of the B.1.1.7 variant, which was first identified in the United Kingdom, according to the latest update from the CDC. So far, no cases of the variant strain identified in South Africa have been reported in the U.S., but Fauci said public health officials are looking for it.

"We're following very carefully the one in South Africa, which is a little bit more concerning, but nonetheless not something that we don't think we can handle," he said.

Despite challenges with vaccine distribution and administration, the U.S. "can and should" vaccinate 70% to 85% of adults by the end of the summer, Fauci told CNN on Thursday evening. If that happens, people could begin to return to some sense of normalcy by the fall, he added.

"When you put…the pedal to the floor, you can get it done," he said.

If the U.S. administered one million shots per day, it would take until the end of 2021 to fully vaccine 75% of adults, according to a CNN analysis. Fauci said he believes the U.S. can give more than one million shots per day. On Friday afternoon, an updated tally from the CDC showed that 1.6 million shots were given in the past 24 hours, which was the largest single-day increase yet reported.

"I'd like it to be a lot more," Fauci told CNN. "If we can do better than that, which I personally think we likely will, then great."