The U.S. is now analyzing about 14,000 coronavirus cases each week with genetic sequencing to detect faster-spreading variants, Centers for Disease Control and Prevention Director Rochelle Walensky said.

That’s up from 250 sequences a week when Walensky took office last month, she told a House Appropriations subcommittee panel Tuesday morning.

New variants of the SARS-CoV-2 virus first detected in the U.K., South Africa and Brazil appear to spread more efficiently. Each of those variants has been found in the U.S., adding urgency to the country’s effort to understand how they’re spreading.

About 3% of all cases are being sequenced to find variants, Walensky said. “That obviously needs to scale up,” she said.

The CDC is working with seven academic institutions to sequence about 4,000 samples a week, and commercial labs are sequencing about 6,000 cases a week, Walensky said. They are expected to further expand capacity.

Congress is proposing $1.75 billion in additional funding to expand sequencing as part of President Joe Biden’s economic stimulus plan.

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