The US is facing at least seven different versions of Covid-19 Omicron as the nation heads into winter when health officials anticipate another wave of viral infections.
Although the omicron BA.5 variant remains dominant in the country, it is gradually losing ground to other versions of the virus, according to data from the Centers for Disease Control and Prevention released Friday.
Omicron BA.5 was fragmented into several new but related variants including BQ.1, BQ.1.1 and BF.7. The UK Health Security Agency said in a report earlier this month that these three variants show a growth advantage over BA.5, the most contagious version yet.
In the US, omicron BA.5 accounts for about 68% of all new infections, compared to about 80% in early October. According to CDC data, BQ.1, BQ.1.1, and BF.7 together cause about 17% of new infections.
About 3% of new infections are due to BA.2.75. and BA.2.75.2, which are related to the omicron BA.2 variant that caused a dent in the cases in the spring but was pushed out.
Scientists from Peking University in China found that Omicron BA.2.75.2 and BQ.1.1 were best at evading immunity from previous BA.5 infection and multiple antibody drugs. The study, published in early October, was not peer-reviewed.
dr Ashish Jha, the White House Covid response coordinator, said earlier this week that US public health officials are closely monitoring these variants because they are good at bypassing prior immunity.
“The reason we’re pursuing them is because they’re either much more immune-invasive or they render many of our treatments ineffective,” Jha said. “Those are the two main things that catch our attention.”
But Jha said the new Omicron boosters that the US began rolling out last month should offer better protection against these emerging variants than the first-generation vaccines. The boosters target BA.5 and the resulting variants are all Omicron and most descended from BA.5.
Jha urged all eligible Americans to get the new boosters by Halloween so they have full protection for Thanksgiving when family celebrations are in full swing.
However, the Peking University scientists said the immune avoidance of variants such as BA.2.75.2 and BQ.1.1 could mean that the BA.5 booster shots do not provide broad enough protection.
It’s unclear how much more effective the boosters will prove in the real world. The Food and Drug Administration approved the recordings without direct human data, relying instead on clinical trials of a similar recording developed against the original version of omicron, BA.1.
Pfizer and BioNTech released the first human data from its BA.5 recordings on Thursday. They elicited a significant boost in the immune system against Omicron BA.5 in a laboratory study examining blood samples from adults aged 18 and over, the companies said.