As the ommicron coronavirus subvariant BA.5 rages across the US — accounting for an estimated 54 percent of the country’s cases — experts are looking at another subvariant that threatens to be on its tail.
The subvariant is called BA.2.75 and was first discovered in India at the end of May. Against the background of BA.2 and BA.5 circulating in India, the newcomer BA.2.75 started to gain ground quickly in June. This week it reached 23 percent of recent virus samples over there. Meanwhile, BA.2.75 spread beyond India’s borders. It is now present in about 10 other countriesincluding the US, according to the World Health Organization.
Being experts Worried about the new sub-variant, not only because of its meteoric rise. It has different mutations in its spike protein– the crucial protein that allows the virus to attach to human cells and the protein that acts as an important target for immune responses. In particular, BA.2.75 has key mutations that suggest it could be good at: evade antibody responses in humans vaccinated and/or previously infected with prior omicron subvariants.
“This subvariant seems to have a few mutations on the receptor-binding domain of the spike protein, so that’s clearly an important part of the virus attaching to the human receptor, so we need to look out for that,” Dr. Soumya Swaminathan, the chief scientist of the World Health Organization said in a video explanation this week†
Swaminathan notes that the number of samples and sequences is still low for now and that our understanding of this version of the virus is limited. “It’s too early to know whether this subvariant has properties of additional immune evasion or, indeed, of being more clinically serious. We don’t know. So we’ll have to wait and see,” she said, adding that the WHO is closely monitoring the subvariant.
American situation
So far, three cases of BA.2.75 have been discovered in the US, which were identified in California and Washington state. Helix — a California-based viral surveillance company that is working with the Centers for Disease Control and Prevention to detect emerging coronavirus variants — confirmed the third US case to Ars in an email Friday. Samples for the three US cases were collected on June 14, June 15, and June 27.
Helix said it’s too early to predict how BA.2.75 will pan out in the US, but the sub-variant is worth keeping an eye on, echoing warnings from outside experts.
Meanwhile, BA.5 rages across the US. The prevalence of the previous prevalent ommicron subvariant, BA.2.12.1, has fallen to an estimated 27 percent. BA.4 — a subvariant that shares the same spike mutations as BA.5 and has spread elsewhere besides BA.5 — appears to have dropped out, accounting for just 16.5 percent of U.S. cases.
Amid the rise of BA.5, cases have maintained a high plateau, although many cases discovered through rapid home testing go unreported. According to tracking by The New York Times, there are an average of about 108,000 new cases per day in the country. Some experts are anxiously waiting to see if there will be a bump after Independence Day celebrations. Just before the holidays, the positivity rate of reported tests hit about 17.5 percent.
Otherwise, daily hospital admissions are up 15 percent in the past two weeks to an average of 35,651. Intensive care admissions also rose by 16 percent. Deaths remain plateau at about 320 per day.
