CDC Gearing Up to Track Three Covid Variants in U.S., Chief Says

(Bloomberg) -- Three worrisome Covid-19 variants are now circulating in the U.S. and the federal government needs significance resources to track their progress, according to the head of the Centers for Disease Control and Prevention.

The variants, which emerged initially in the U.K., South Africa and Brazil, have all now been seen in the U.S., said Rochelle Walensky, the CDC chief, in a question and answer session hosted by the Journal of the American Medical Association.

The agency has already warned that the highly contagious mutant strain that emerged in the U.K. could become dominant among Americans in the next two months. There are now 19 cases of the mutation first reported in South Africa in the U.S., she said, and two cases of a variant initially detected in Brazil in two states.

One priority for fighting the variants in the U.S. is to put strong public health surveillance in place that can track changes in the virus, according to Walensky. The CDC is partnering with state laboratories to get 750 samples a week to sequence, she said, and has arranged with private and academic laboratories to contribute data as well.

Additionally, the CDC is already working with makers of current vaccines to see if they can tweak their shots to work better against the variants, according to Walensky. “So that if down the line we need a bivalent vaccine or a booster vaccine, we’re ready to go,” she said.

On Wednesday, a laboratory study showed that the current Pfizer Inc.-BioNTech SE vaccine stimulated roughly two-thirds lower levels of neutralizing antibodies against the variant that emerged from South Africa.

What the lab data means in practice, though, remains to be seen.

“It is unclear what effect a reduction in neutralization by approximately two-thirds would have” on protection from Covid-19 caused by the South Africa variant, the Pfizer study concluded. Pfizer and BioNTech said in a statement that there’s no real-world evidence that the South African variant can elude their shot.

Resources Needed

In the JAMA session, Walensky indicated the CDC needs significant resources to keep on top of the issue. Each sample can cost $150 to sequence, she said, and there remains a question of who is going to be able to analyze all the samples quickly and efficiently.

The first priority, though, is simply to have less virus circulating, she said. She estimated that about 20% of the population likely has natural immunity already from being infected, she said, and about 5% of Americans have had two doses of a vaccine so far.

That’s a good start, according to Walensky. But “if the variants are more transmissible,” she said, “we have a higher bar to get to in terms of herd immunity,” the point when enough people have immunity to contain spread. Health officials have said the U.S. has to have 70% to 85% of its population immunized to reach that level.

330 Million Individuals

Come Spring, Walensky’s concerned that many Americans will have had enough of masks and social distancing and start abandoning still-needed mitigation strategies. “How this goes depends on 330 million individuals,” she said.

Walensky, who most recently was chief of infectious diseases at Massachusetts General Hospital, has treated patients on the front lines of the Covid-19 outbreak.

She’s inherited an agency whose reputation has been tarnished. Early in the pandemic, the Trump administration halted the CDC’s briefings and the agency faded from view. By the fall, mounting evidence showed how administration officials interfered in the agency’s work, slowing down publication of guidance and stalling access to $1 billion in pandemic aid Congress intended for the agency.

Since moving into the CDC’s top spot, she has been highly visible in public briefing and events like the JAMA Q&A session.

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