With COVID upticks being seen across parts of Europe, many coinciding with a rise in BA.2 or “stealth omicron” cases, what does that signal for the U.S. as restrictions ease?
Chicago’s top doctor said Thursday she is particularly concerned about the state of Europe’s COVID cases.
“I’m going to be honest, I am concerned about what’s happening in Europe because I think there is not a full understanding of it,” Chicago Department of Public Health Director Dr. Allison Arwady said during a Facebook Live Thursday.
As most COVID-19 restrictions are relaxed across Europe, including Austria, Britain, Denmark, Germany and France, the numbers of infections have inched higher in recent days. The uptick is driven in part by the slightly more infectious omicron descendant BA.2 and by people largely abandoning masks and gathering in bigger groups.
In the last two weeks, COVID-19 hospitalizations and deaths have both risen slightly in Britain.
Elsewhere, South Korea had its deadliest day yet of the pandemic on Tuesday, with 293 deaths reported in the latest 24 hours, as the country grapples with a record surge in coronavirus infections driven by the fast-moving omicron variant.
China banned most people from leaving a coronavirus-hit northeastern province and mobilized military reservists Monday as the fast-spreading “stealth omicron” variant fuels the country’s biggest outbreak since the start of the pandemic two years ago.
“I think it’s very likely that what we’ve seen in Europe, where BA.2 is increasing in relative proportion is going to happen here,” said Dr. Isaac Ghinai, medical director for lab-based surveillance at CDPH. “We’re going to see BA.2 causing an increasing proportion of the number of cases. We’ve already seen that.”
BA.2, also known as “stealth omicron,” is considered a subvariant of omicron.
BA.2 has several key mutations, with the most important of those occurring in the spike protein that studs the outside of the virus. Those mutations are shared with the original omicron, but BA.2 also has additional genetic changes not seen in the initial version.
Ghinai added that he believes the rise of BA.2 is “less concerning” than omicron was when it was first detected in the U.S. late last year.
“I don’t expect the same kind of surge that we saw in late 2021 as a result of BA.2,” he said. “That’s not to say there won’t be changes, especially at some point – we’re at a nearly historic low in terms of COVID here in Chicago, it’s very likely that there may be some changes in transmission. I don’t expect it to be a surge like we saw the last few months because of omicron, because of delta.”
Stealth omicron had already been detected in Illinois earlier this year.
Northwestern Medicine’s Center for Pathogen Genomics and Microbial Evolution said the subvariant was found in a Chicago resident who was tested for COVID-19 on Jan. 18.
According to data from the Centers for Disease Control and Prevention, variant surveillance measures in the Midwest indicate BA.2 cases are doubling every seven days.
Arwady stressed that while the rise of COVID in other countries could be a sign of what’s to come, it’s not a guarantee.
“I do certainly have some concern, particularly about what we’re seeing in Europe, but there are a lot of differences there,” she said.
Arwady said that while her office has been in communication with the UK, the rising metrics could be due to any combination of restrictions lifting, waning immunity or BA.2 and other variants.
She noted that many countries currently seeing spikes, such as China and Australia, “were really aiming for a zero-COVID approach.”
“What I think we’ve seen with omicron – BA.1, BA.2, doesn’t matter – it is so much more infectious, so much more contagious, that countries that had been aiming for a zero goal, it’s really not possible with a variant that infectious. And so what’s important is that a lot of these countries, while they’re seeing surges in cases, it’s not turning into the, you know, sort of the severe illness, the hospitalizations because they’re highly vaccinated. My worry is we are not as highly vaccinated as a lot of those other countries.”
Preliminary data indicate vaccinations and boosters are similarly effective in preventing symptomatic cases of BA.1, the original omicron variant, and BA.2.
“People are watching BA.2 very closely because it appears to have a growth advantage over BA.1,” Ghinai said. “So to put that into, kind of, plain English, it means it’s probably more transmissible than BA.1. But the difference between BA.1 and BA.2 is much, much smaller than the difference between omicron as a whole and delta as a whole.”
According to Ghinai, evidence so far suggests infection with one omicron sublineage is believed to provide protection from other omicron sublineages.
“Obviously we’re watching this closely, we’re concerned about it, but I have been reassured in some, you know, really good real world studies that suggest, you know, about a 90% protection in at least the short term,” Arwady said. “So, people who just recently, if they had, for example, a breakthrough infection from the original omicron, BA.1, it looks unlikely based on what we’ve seen in other setting that we would expect those same people to likely be particularly susceptible to BA.2.”
