The CDC estimates that the Omicron BA.4 and BA.5 sub-variants together have become dominant in the US.

Continuing its swift march across the United States, Omicron sub-variants known as BA.4 and BA.5 together have become dominant among new coronavirus cases. new estimates Tuesday from the Centers for Disease Control and Prevention.

As of the week ending Saturday, BA.4 accounted for 15.7% of new cases and BA.5 for 36.6%, accounting for about 52% of new cases in the United States, and experts say the numbers should increase in the coming weeks. .

The statistics, released Tuesday morning, are based on simulations and are subject to revision as more data becomes available, which happened in late December when the agency’s estimates missed.

Less than six months after BA.4 and BA.5 were first discovered in South Africa, the two sub-variants appeared in the United States, overtaking two earlier Omicron sub-variants, including BA.2, which was the first. prevailing version earlier this spring. Another, BA.2.12.1, was dominant only as of the week ending June 18, according to CDC estimates. During the winter, the form of Omicron, first introduced in the United States, led to a spike in cases. Prior to this, the Delta option was dominant in the US since early summer.

BA.4 and BA.5 are escape masters, able to elude some of the antibodies produced after coronavirus vaccinations and infections, including those caused by some earlier versions of Omicron. This may explain why these sub-options are spreading even faster. than others in the Omicron family. But little evidence yet that they cause more severe illness.

Sub-variants BA.4 and BA.5 have been discovered worldwide and they are fueled outbreak in South Africa spring, despite widespread pre-existing immunity to the virus. The wave was not as high as previous waves in South Africa and deaths did not rise as sharply. Just last week South Africa canceled their rules which required the wearing of masks in enclosed public places.

More than 100,000 new coronavirus cases have been reported daily in the United States in recent weeks. according to the New York Times databasea figure that reflects only part of the true number. Many infections go unreported in official reports. Some scientists estimate that the current wave of cases is the second largest during the pandemic.

As of Monday, the number of hospitalizations in the US up to 6 percent up to 31,000 people a day on average over the past two weeks, according to federal data. According to state and local health authorities, the average number of new deaths remains below 400 per day. This is just a fraction of the thousands seen daily during Omicron’s winter peak.

“But in my opinion, 250 deaths a day is still too much,” the doctor said. Rochelle Walensky, director of the CDC, said last week in Aspen, Colorado. “The deaths we see usually among the elderly, debilitated, with many comorbidities, highly vaccinated or unvaccinated.”

Many Americans with risk factors say they feel ignored and abandoned. as their governments and neighbors sought to return to normalcy.

As always, the spread of the virus is a regional matter. In the Northeast and Midwest, the number of known cases has been declining for several weeks, while in the South and West, the number of cases is increasing.

Across the country, public health regulations continue to be lifted, including the ending on Saturday due to an indoor mask mandate for Alameda County, the second most populous county in the San Francisco Bay Area. In New York, Broadway theaters – save for one are lifting their mask requirements from Friday. Even the long-standing requirement to take a coronavirus test before flying to the US from abroad It was dropped this month.

While the recent introduction of vaccines for children aged 6 months to 5 years has been a welcome development for many parents and kindergarteners, experts do not expect availability pediatric doses to change the overall trajectory of the pandemic in the United States.

natural weakening protection of the vaccine against infection over time, along with the immune evasion of BA.4 and BA.5, may explain why these sub-variants are able to spread rapidly. It also gave relevance development or Omicron oriented boosters. While the vaccine manufacturers were chasing develop thesethey are based on other versions of Omicron, and it has not yet been clear how well they can protect against BA.4 and BA.5 infections.

Preliminary laboratory research data suggests that unvaccinated people infected with a version of Omicron known as BA.1 can easily become re-infected with BA.4 or BA.5. The study suggests that vaccinated people are likely to feel somewhat better.

But as the virus evolves, no one can tell if the modified vaccines might be obsolete by the time they become available.

“What we don’t know is what will happen with the new vaccine in the fall,” Valensky said from Aspen. “I really think we’re going to need more vaccines.”