February 5, 2023

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The highly transmissible BA.5 omicron subfactor is now the dominant strain of coronavirus in the United States, accounting for nearly 54% of Covid-19 infections last week, according to the Estimates From the Centers for Disease Control and Prevention, as cases rise and drug companies work to reformulate vaccines to target new viral strains known to be able to evade antibodies.

key facts

BA.5 and the closely related Omicron BA.4 subchain accounted for 70% of coronavirus infections for the week ending July 2, according to CDC estimates, which may be subject to changes.

BA.2.12.1, which helped boost Covid-19 cases when it was prevalent in the spring, made up only 27% of cases last week.

The news comes a week after the Food and Drug Administration recommended drug companies update their coronavirus vaccine boosters by fall to target BA.4 and BA.5, in anticipation of a surge in Covid-19 in the winter.

Also comes as Covid-19 cases It has been on the rise in recent months, with the average number of new infections in the United States averaging 94,345 cases per day in the week ending July 4, more than three times the 30,558 reported daily as of April 10, but Well below the January peak of over 800,000 cases per day.

hospitalization Trending up too: Covid-19 hospitalizations averaged 4,376 per day in the seven-day period ending July 3, more than double the 1,428 average per day in early April, although the numbers are still much lower than they were On it during the increase of the Corona virus in the winter, when the number of daily hospitalizations exceeded 20,000.

Amazing fact

More than 16% of coronavirus tests in the United States came back positive on average last week, the highest positive rate since early February, according to the Center for Disease Control.

main background

BA.4 and BA.5 were first detected earlier this year in South Africa, where the strains became dominant, and eventually made their way to the United States in late March, although the omicron subrain BA.2 remained the dominant variant. for several weeks. All three sub-cells contain specific mutations in their spiny proteins – the part of the virus that attaches to the human cell – that help them evade the immune system, and the data suggests that BA.5 is better at evading antibodies than previous coronavirus infections and vaccines. Countries around the world like United kingdom It is also seeing an increase in cases as BA.4 and BA.5 become the most prevalent strains of coronavirus. BA.4 and BA.5 combined dominant Covid-19 substations in the US two weeks ago, accounted for 55% of cases.

What to watch

A steady rise in Covid-19 cases during the summer. The rise in new sub-variants that are more contagious from previous strains and able to escape the immune system indicates “a significant circulation of the virus this summer,” said Dan Baruch, MD, director of the Center for Virus and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, Tell The The Wall Street Journal last week.

in-depth reading

The FDA recommends using Covid boosters to target highly contagious Omicron subvariants — here’s when you should get your next shot (Forbes)

What to know about the latest, most infectious omicron sub-variants (time)

Full coverage and live updates of coronavirus

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