Topline
The highly transmissible BA.5 omicron subvariant is now the dominant coronavirus strain in the U.S., accounting for nearly 54% of Covid-19 infections last week, according to estimates from the Centers for Disease Control and Prevention, as cases rise and drug companies work to reformulate vaccines to target new virus strains known for their ability to evade antibodies.
A nurse tends to a Covid-19 patient in the Intensive Care Unit.
Key Facts
BA.5 and the closely related omicron substrain BA.4 comprised 70% of coronavirus infections for the week ending July 2, according to CDC estimates, which may be subject to changes.
The BA.2.12.1 variant, which helped fuel a spike in Covid-19 cases when it was dominant in the spring, accounted for only 27% of cases last week.
The news comes a week after the Food and Drug Administration recommended that pharmaceutical companies update their coronavirus vaccine booster shots by the fall to target BA.4 and BA.5, in anticipation of a winter Covid-19 surge.
It also comes as Covid-19 cases have been on the rise in recent months, with the United States averaging 94,345 new infections per day in the week ending July 4, more than triple the 30,558 daily cases reported as of April 10, but well below the January peak of more than 800,000 per day.
Hospitalizations have trended upwards, too: Covid-19 hospital admissions averaged 4,376 per day in the seven-day period ending July 3, more than twice the average of 1,428 per day in early April, though numbers are still much lower than during the winter coronavirus surge, when daily hospitalizations topped 20,000.
Surprising Fact
Over 16% of U.S. coronavirus tests came back positive on average last week, the highest positivity rate since early February, according to the CDC.
Key Background
BA.4 and BA.5 were first discovered earlier this year in South Africa, where the strains became dominant, and they eventually made their way into the U.S. in late March, though omicron substrain BA.2 remained the dominant variant for several weeks. All three of the substrains have specific mutations in their spike proteins—the part of the virus that binds to the human cell—that help them evade the immune system, with data suggesting BA.5 is even better at escaping antibodies from previous coronavirus infections and vaccines. Countries around the world like the United Kingdom are also seeing a spike in cases as BA.4 and BA.5 become their most prevalent coronavirus strains. BA.4 and BA.5 combined became the dominant Covid-19 substrains in the U.S. two weeks ago, accounting for 55% of cases.
What To Watch For
A continued spike in Covid-19 cases over the summer. The rise in new subvariants that are even more contagious than previous strains and capable of escaping the immune system suggest “substantial circulation of virus this summer,” Dan Barouch, director of the Center for Virology and Vaccine Research at Boston’s Beth Israel Deaconess Medical Center, told the Wall Street Journal last week.
Further Reading
What to Know About the Newest, Most Contagious Omicron Subvariants (Time)
Source: https://www.forbes.com/sites/madelinehalpert/2022/07/05/highly-contagious-ba5-variant-becomes-dominant-in-us-as-covid-cases-rise/