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The two newest subvariants of Omicron, BA.4 and BA.5, are spreading across the U.S. and making up a higher percentage of new cases, prompting concerns about increased transmissibility.
The subvariants represent 13% of new COVID-19 cases, according to the latest CDC data, up from 7.5% the week before and 1% in early May. About 7.6% of new cases are BA.5, and 5.4% are BA.4.
Other Omicron subvariants that have caused surges, BA.2 and BA.2.12.1, still make up most cases, CDC data shows. BA.2.12.1 is currently the dominant form of the coronavirus, accounting for 62.2% of cases, followed by BA.2 with 24.8% of cases.
“For the summer, going into the winter, I expect these viruses to be out there at relatively high levels,” Alex Greninger, MD, PhD, assistant director of the clinical virology lab at the University of Washington, told CNN.
“The number of cases, the sheer disruptions of the workforce — it’s just a very high, high burden of disease,” he said.
The new BA.4 and BA.5 are considered more contagious than the BA.2 subtypes and are expected to become the dominant subvariants, according to The New York Times. Public health officials predicted that the subvariants could lead to another surge in the U.S. but haven’t been able to determine whether the subvariants will lead to an increase in hospitalizations and deaths.
Omicron and all of its lineages, including BA.4 and BA.5, are considered “variants of concern” by the CDC and World Health Organization, which suggests evidence of increased transmissibility, severity, and impacts on diagnostics, treatments, or vaccines.
BA.4 and BA.5 appear to be more than four times as likely to escape antibodies in fully vaccinated and boosted people as the BA.2 viruses, according to a new preprint study from researchers in New York. They also found a drop in protection for people who have recovered from breakthrough Omicron infections.
In the U.S., BA.4 and BA.5 have spread the most in parts of the South and Southwest, CDC data shows, with the highest proportions seen in Texas, Louisiana, Oklahoma, Arkansas, and New Mexico. In that region, the two subvariants made up more than 22% of new cases last week
During the last few weeks, the U.S. has averaged about 100,000 new cases per day, according to the data tracker from the Times, up from less than 30,000 in late March. Hospitalizations initially increased in the Northeast and have begun to decline, though they are now rising elsewhere. New deaths have fluctuated between about 250 to 400 per day, the newspaper reported.
Overall, the number of new COVID-19 deaths will continue to increase during the next 4 weeks, according to new estimates by the CDC.
The forecast shows that more than 12,000 COVID-19 deaths will likely be reported during the next month, which would boost the daily average to more than 500. This is the fourth consecutive week the agency has predicted an increase in deaths.
Créditos: Comité científico Covid