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The CDC that it's tracking a new variant of SARS-CoV-2 -- named BA.2.87.1 -- given its large number of changes in the spike protein.

So far, no cases of BA.2.87.1 have been identified in the U.S. In fact, the strain has only been detected in South Africa -- just nine times from September to December 2023 -- and doesn't yet appear to be highly transmissible, the agency said.

However, experience with BA.2.86 showed that the ability of the virus to transmit can change quickly, according to the CDC. While that variant initially spread relatively slowly, its descendant JN.1 "spread very quickly to become the dominant variant across the globe."

South Africa's cases of BA.2.87.1 were posted to a public database on January 31. That country hasn't seen a detectable increase in COVID cases in recent weeks, CDC said.

"The fact that only nine cases have been detected in one country since the first specimen was collected in September suggests it does not appear to be highly transmissible -- at least so far," the agency wrote.

BA.2.87.1 has more than 30 changes in the spike protein compared with XBB.1.5, the variant that the updated vaccine is designed to protect against. "In theory, variants with multiple changes in the spike protein could increase the possibility of escape from this immunity," the CDC wrote.

However, the agency's announcement noted that several variants over the past year have had "significant changes in their spike protein" yet "existing immunity from vaccines and previous infections still provides good protection."

"We don't yet know how well existing immunity holds up against BA.2.87.1," the CDC wrote. "However, our immune systems now have several years of experience with this virus and vaccines, generally providing protection against a wide range of variants."

CDC issued a similar alert about closely monitoring BA.2.86 last August, noting that it too had more than 30 novel mutations and could be "more capable of causing infection" in those who had been vaccinated or previously had COVID. But it never took off, until a single mutation turned it into JN.1, which is now the dominant variant in the U.S.

Indeed, CDC's shows that for the 2-week period ending February 3, JN.1 accounted for an estimated 93% of cases, followed by HV.1 at 2.3% of cases.

Researchers have previously told 乌鸦传媒 that SARS-CoV-2 will continue to mutate and that there shouldn't be much concern about new variants before there's substantial information about transmission and disease severity.

Shishi Luo, PhD, head of infectious diseases at the population genomics company Helix, said in an earlier interview that experts are now watching hospitalizations "[r]ather than trying to follow what the new mutations are and seeing if neutralization assays or experiments are done to investigate the functional impact of the mutation."

Continued surveillance for new COVID variants is important, Luo said, as is surveillance for other respiratory pathogens including influenza and respiratory syncytial virus.

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