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Omicron subvariants, known as BA.4 and BA.5, now represent 13 percent of new coronavirus cases, up from 7.5 percent a week ago and 1 percent in early May. according to new estimates From the Centers for Disease Control and Prevention.
The spread of subvariables adds further uncertainty to the trajectory of the pandemic in the United States, where current case numbers are likely. an important understatement. But scientists remain unclear whether it will lead to a new wave of infections or spikes in hospitalizations and deaths.
The new figures released Tuesday are based on modeling and CDC estimates. I missed the mark before. However, the general trend shows that BA.4 and BA.5 can outperform the competition. two other Omicron sub-variants, BA.2 and BA.2.12.1 together explains most US casessaid Denis Nash, An epidemiologist at the CUNY Institute for Public Health and Health Policy.
Dr. “This could happen very quickly,” Nash said.
Data on BA.4 and BA.5, first detected in South Africa in early 2022, remain limited. However, these variants are spreading faster than previous versions of Omicron, such as BA.2, and may be better at bypassing the immune system’s defenses. So far, there is not much evidence that they cause more severe disease, although more studies are needed.
“How similar is that to us?” said. “I think it is possible that we may see another wave” fueled by BA.4 and BA.5. But if the United States follows South Africa’s example—which is not a guarantee—the wave could be more modest than previous fluctuations and lead to less significant increases in hospitalizations and deaths, he said.
USA averaged over the past few weeks. about 100,000 new cases per dayAccording to the New York Times database, less than 30,000 at the end of March.
and during hospitalizations began to decline in the northeast, they rise elsewhere. Trends in the number of new deaths, which fluctuated between about 250 and 400 per day for the past month, are less clear, although the metric average. much lower than during the winter Omicron surge. (Data reporting delays around the Memorial Day holiday are making recent statistics less reliable.)
Globally, the latest data shows that BA.4 and BA.5 still represent a relatively small proportion of cases, but this may change in the coming weeks. Inside a new reportThe UK Health Security Agency noted that in many countries, the two sub-variants replaced BA.2, as quickly as BA.2 replaced the original version of Omicron.
In the United States, new sub-variants are gaining ground. In the week ended June 4, BA.5 accounted for an estimated 7.6 percent of cases, and BA.4 accounted for 5.4 percent of cases, up from 4.2 percent and 3.3 percent, respectively, from the previous week. was his reputation.
Subvariants have become particularly common in parts of the southern United States. In the region that includes Arkansas, Louisiana, New Mexico, Oklahoma and Texas, BA.4 and BA.5 account for more than one in five infections, according to new figures.
The wastewater data also highlight the spread of subvariables. For example, in early May in Missouri, BA.4 and BA.5 emerged in few state sewers or geographic areas where wastewater was fed to a single treatment plant or other collection point. The subvariables are now detectable in more than half of them, said Marc Johnson, a virologist at the University of Missouri who analyzed the state’s wastewater.
Preliminary evidence from laboratory research It suggests that unvaccinated people infected with the original version of Omicron, known as BA.1, could easily be reinfected by BA.4 or BA.5. (The study shows that people who have been vaccinated are more likely to do slightly better.)
This immunity avoidance, in addition natural decrease in protection against infection over timemay explain why the newest subvariables are spreading so quickly.
Sarah Cahalan contributed.
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