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At least one of two or more new variants of SARS-CoV-2 is likely to have spread to the community in the United States, but they are unlikely to have a large impact on the effectiveness of the vaccine or standard precautions, they said. CDC officials at a briefing.
The first reported US case of the highly communicable variant of the coronavirus first seen in Britain (dubbed SARS-CoV-2 VUI 202012/01) was confirmed Tuesday in a Colorado man with no travel history. The strain can be at least 56% and up to 70% more transmissible than the “wild-type” virus, although not more serious or deadly. The British variant has likely been circulating there since September 2020.
Another extra-transmissible variant of South Africa emerged independently and appears to be spreading internationally now, and Nigeria has reported that another variant emerged there. Neither has yet been isolated in the United States.
“We hope to see new variants emerge over time,” said Henry Walke, MD, MPH, CDC’s COVID-19 Incident Manager, during Wednesday’s news conference.
Exactly how many variants have emerged so far is “impossible to answer,” because it depends on how you set the threshold for how different a virus must be to represent a variant, said Gregory Armstrong, MD, director of Advanced Molecular Detection at the CDC. Program.
The government has been working on a strain surveillance system since November with two national laboratories to analyze genetic sequences of SARS-CoV-2 samples from around the country to determine the penetrance of newly identified variants. Armstrong said findings are expected in the next few days.
It is not yet clear how well vaccines and other treatments will work against these variants. A study published on the prepress server medRxiv suggested that convalescent plasma does not work as well against variants.
However, “from what we know from experience with this mutation and other mutations, it is unlikely to have a large impact on vaccine-induced immunity or the existing immunity of older strains,” Armstrong said.
“We know that some of these mutations can reduce the effectiveness of monoclonal antibodies,” which bind to a particular portion of the target antigen, Armstrong noted. But immune responses derived from infections or vaccines recognize multiple parts of the spike protein, he added.
“Experts generally agree that mutations like this are unlikely to have much of an impact on neutralization,” he said. “It may have a small impact, but keep in mind that the amount of immunity induced by natural infection or by the vaccine is likely to be large enough that the slightly lowered titer has no noticeable effect.”
In vitro studies of the UK variant are underway and should provide a more definitive answer, Armstrong said.
Furthermore, Walke said, there is no reason to think that the recommended measures to reduce the spread – washing hands, keeping your distance, wearing a mask, and avoiding large gatherings – will not work against these variants.
“We are pushing our very messages that we have been pushing from the beginning,” he said. “While we believe that this variant that originated in the UK … can potentially transmit more than the wild type, we strongly believe that our mitigation measures in our guide will now work.”
Last updated December 30, 2020
