Cases of the highly transmissible omicron subvariant appear to be doubling every week in the U.S., but there isn't clear evidence BA.2 will cause another major surge, epidemiologist Michael Osterholm, PhD, told Becker's March 2.
The subvariant accounted for an estimated 8.3 percent of COVID-19 cases in the week ending Feb. 26, up from 4.4 percent a week prior, according to CDC estimates.
BA.2 was dominant in 18 countries as of Feb. 22, but no trends have emerged to suggest the subvariant is fueling a rise in cases.
"If we look at other countries around the world where BA.2 has taken off … there's no discernable patterns," said Dr. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota in Minneapolis.
COVID-19 cases are rising in some countries where BA.1, the original omicron strain, is still dominant and falling in others. Countries where BA.2 is dominant are reporting mixed case trends, according to Dr. Osterholm.
The U.S. has seen steep drops in cases relative to omicron's peak in January, when the daily average for new cases surpassed 800,000. As of March 2, the daily case average fell below 55,000, data from The New York Times shows.
Dr. Osterholm said the nation's case decline may be leveling off, based on trends from other countries.
"In some countries the peak does have initial steep drops, and it tends to level off at a level that is substantially higher than it was before omicron showed up … so I think this is a huge challenge for some areas still seeing substantial activity."
While case numbers and hospitalizations have seen great improvements, today's figures would've been considered excessively high earlier in the pandemic, Dr. Osterholm said, noting there was a time when 40,000 cases a day was considered "a house on fire."
His points underscore how society's expectations regarding baseline levels of virus activity have evolved throughout the pandemic alongside shifting trends in case volumes and increased availability of COVID-19 vaccines and therapeutics.
Cases will likely continue to drop over time, Dr. Osterholm said, adding he is hopeful cases will reach or fall below levels not seen since last June, when the nation's new case average fell below 12,000.