SAN JOSE (KPIX) — Despite a steady decline in COVID-19 cases in Santa Clara county as well as the rollout of the vaccine, Dr. Anthony Fauci warned Thursday the pandemic could get worse as new mutant variants threaten any progress that has been made.

“We’re much more concerned about the South African strain,” Fauci said.

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Two adults in South Carolina came down with the nation’s first known cases of the South African strain and the CDC has projected the UK variant will become dominant in the United States by March.

“We think it’s somewhere between 30% and 70% more transmissible or at least it spreads faster,” said the UK government’s chief scientific adviser Patrick Vallance. “We don’t yet know why.”

On Thursday, Santa Clara county reported 828 new coronavirus cases. For reference, the county reported 1,736 cases on Jan. 9 and 1,551 on Jan. 10.

“I just feel that it’s even more important now to get vaccinated than ever,” said Jim Carter who was among the 500 people who were vaccinated at the Mexican Heritage Plaza in east San Jose Thursday.

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The location turns into a popup vaccination clinic on Tuesdays and Thursdays with the capacity to vaccinate 500 people each day it’s open.

“I feel safe and secure,” said Concepcion Flores, who received her vaccination at the popup clinic.

The plaza’s executive director, Jessica Paz-Cedillos, said that some people have become emotional after receiving the dose.

“During vaccination days, you see a lot of hope,” she said. “We’ve had people, they’re smiling.”

Flores, who watches the news every day for COVID-19 updates, said she hopes Fauci’s warning that the pandemic could worsen before it gets better doesn’t become reality.

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“I just pray that it doesn’t happen,” Flores said.