The BA.2 omicron subvariant is accounting for more than half the COVID-19 cases across Chicago as of Thursday, as the city continues to monitor the widespread strain, according to the city's top doctor.
"Just as projected, we were estimating that approximately [by] the end of the month we would have seen the majority, meaning more than 50%, of our cases here in Chicago and in the Midwest, being that omicron BA.2," Chicago Department of Public Health Commissioner Dr. Allison Arwady said Thursday. "And in fact that's exactly where we are, 50.4%."
People infected with the original strain of omicron, BA.1, are likely more than 90% protected against the omicron BA.2 subvariant, Arwady said, which differs from that of delta.
Arwady added that city health officials do not expect many people to get reinfected with BA.2. However, she said her team remains concerned for those who have not yet been vaccinated against COVID.
According to the top doctor, Chicago has typically followed the East Coast in terms of COVID spread, which she added has led to a promising point.
Arwady said that in New York City, omicron's BA.2 subvariant is currently making up about 70-75% of COVID cases, though there hasn't been a major surge in metrics. Should Chicago continue its traditional pattern, she said the city will not likely see a surge despite BA.2 rising.
Chicago has been seeing an uptick in COVID cases and test positivity, based on CDPH data. However, health officials noted that the city remains in "good control" over the outbreak after lifting mask and vaccine requirements about one month ago.
Over the past week, 235 Chicagoans on average tested positive for COVID each day, according to CDPH data. Chicago's test positivity rose over the last week to 1.4% on an average of 20,304 tests daily.
Chicago is averaging 11 COVID hospitalizations and less than one death per day, which is nearly the lowest averages since the start of the pandemic, CDPH noted.
"It is not surprising to see a slight increase in cases as behavior changes, but we continue to monitor this closely,” Arwady said. “If the increase in cases does concern people, the most important thing you can do to protect yourself from severe outcomes remains the same: ensure you are up to date with your COVID-19 vaccinations.”
The BA.2 subvariant of COVID, otherwise known as “stealth omicron,” is now the dominant strain of the virus in the Midwest and in the United States, according to new estimates released Tuesday by the CDC.
The estimates peg the percentage of BA.2 cases at 50.4% of all COVID cases in a six-state region of the Midwest that includes Illinois, Indiana, Michigan, Minnesota, Ohio and Wisconsin. CDPH said officials will continue to monitor this strain.
In the United States as a whole, the CDC estimates that 54.9% of all COVID cases are tied to the “stealth omicron” variant, as of this week.
Experts have said that they believed that the BA.2 subvariant would ultimately become the dominant strain of the virus in the United States, following a pattern set in China, Israel, and parts of Europe, all of whom are seeing increases in COVID cases due to the variant.
Dr. Anthony Fauci, the White House’s chief medical advisor, said that he does not anticipate another surge in cases, but says that the new subvariant could cause COVID cases to rise in coming weeks.
According to the U.K. Health Security Agency, the BA.2 subvariant spreads approximately 75% faster than the earlier version of omicron, BA.1. Even still, spikes in cases in the U.K. and Germany caused by the variant have already begun to roll back.
Experts also suggest that BA.2 does not make people sicker than previous strains of the omicron variant, according to data from South Africa and the U.K.