BA.2.75 has a large number of mutations compared to its sister Omicron lineages. Some of these adaptations could allow the virus to bind to cells more efficiently, said Matthew Binicker, director of clinical virology at the Mayo Clinic in Rochester, Minnesota. BA.2.75 was first analyzed in May in India, where it spread rapidly.
A very early analysis of data from India by Raj Rajnarayanan — who is Assistant Dean for Research, NYITCOM at Arkansas State University — indicates that BA.2.75 may have a growth advantage over BA.5. It is not yet clear whether BA.2.75 makes people sicker than previous variants.
BA.2.75 (#Centaurus) still hasn’t taken its foot off the gas pedal in India!
The growth advantage of BA.2.75 over BA.5* and BA.2.38* increased slightly to 324% and 423% (over the last 3 months)
Only one thing is for sure… It Ain’t Over Folks! pic.twitter.com/94Kj50OuNu
— Raj Rajnarayanan (@RajlabN) July 13, 2022
Since it was first identified, the subvariant has been identified in “around 14 countries,” according to WHO’s Covid-19 technical lead, Maria Van Kerkhove. These include Australia, Canada, Japan, Germany, New Zealand, the United Kingdom and the United States
States with consecutive BA.2.75 infections are California — with two cases — and one each in Illinois, New York, North Carolina, Texas, Wisconsin, and Washington. The California cases have been traced to Bay Area sewage samples since mid-June, the San Francisco Chronicle reported.
“It’s still too early to draw too many conclusions,” Binnicker said. “But it seems that, especially in India, transmission rates are kind of showing that exponential increase.”
Tom Peacock, Virologist at Imperial College London cited “the divergent mutation profile, the wide geographical spread and the speed with which new sequences have emerged” as his main concerns about BA.2.75. It may also have an advantage over BA.5 through increased immune evasion.
“Over the last several months, we’ve seen each successive (Omicron) variant have a small transmission advantage over the last,” Dr. Anthony Fauci told the White House’s Covid-19 Response Team briefing on Tuesday. He presented a diagram illustrating the incremental nature of the increasing ability to develop new variants.
WH Covid-19 Response Team
WHO’s Van Kerkhove cautioned that, for BA.2.75, “there are very few sequences available,” and so our understanding of the Omicron branch is limited.
Indeed, funding for Covid surveillance has been cut globally and in the US at the federal, state and local levels, making it more difficult to understand what is happening — or what will happen.
But if BA.2.75 surpasses BA.5, it may follow a similar pattern to its previous variants, staying low for the next month or so and then roughly doubling its share of new cases each week for the next month before become the dominant status variant about 12 weeks after discovery. That would put the nation in the grip of a new surge of Covid as children head back to school in September, around the same time the Delta wave hit last year.
