The prevalence of omicron subvariant BA.5 is declining slightly in the U.S., according to data from the Centers for Disease Control and Prevention.
At its peak in August, BA.5 was responsible for nearly 87% of new coronavirus cases. This week, the CDC estimates that it caused about 83% of infections.
The decline is small but has been steady for about a month. Other strains, like BA.4.6 and BF.7, have started increasing in the meantime.
BA.4.6 is the most prevalent strain behind BA.5. It was responsible for nearly 12% of infections this week.
BF.7, which is an offshoot of BA.5, caused over 2% of cases this week.
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The Biden administration has been pushing updated COVID-19 shots that target the omicron variant ahead of expected coronavirus surges in the fall and winter. The shots are designed to take on BA.4 and BA.5 as well as the original coronavirus strain. Experts expect the future surges to be fueled by BA.5 but warn that the variant scene can change quickly.
“All the data from this new bivalent vaccine have demonstrated that it will protect you against – more likely protect you – against the strains that we have circulating right now, those omicron BA.5 strains, as well as keep you well protected, because we’ve seen that some of that protection can wane over time,” CDC Director Rochelle Walesnky said after getting her updated booster shot this week. “So, we are really encouraging everybody to roll up their sleeves and get this updated bivalent vaccine.”
Meanwhile, the World Health Organization this week warned that its ability to track emerging variants is hampered by declining surveillance and testing.
“Our ability to track variants and subvariants around the world is diminishing because surveillance is declining, and with surveillance declining, the numbers of tests are declining, the numbers of sequences that are being conducted and being shared is declining,” WHO’s technical lead for COVID-19 Maria Van Kerkhove said at a press briefing on Thursday.
She added that COVID-19 “continues to circulate at an incredibly intense level around the world.”
“The more this virus circulates, the more opportunities it has to change, and this is something we are deeply concerned about,” Van Kerkhove said.