Delta variant of COVID-19 ready to ravage unvaccinated in Illinois: ‘Some areas are going to blow up’

The most infectious variant of the coronavirus yet is expected to dominate Chicago and the rest of Illinois within months. What makes it so dangerous? Local experts weigh in.

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A medical worker tests a person for COVID-19 at a basketball court turned into a coronavirus testing center Tuesday in Binyamina, Israel. The Delta variant is sweeping that county as it’s expected to do within months in Illinois.

A medical worker tests a person for COVID-19 Tuesday in Binyamina, Israel. The Delta variant is sweeping that county as it’s expected to do within months in Illinois.


Nearly 16 months into the pandemic, COVID-19 is still finding insidious new ways to invade and devastate the human body.

Front of mind for public health officials in Chicago and beyond is the Delta variant of the coronavirus, which already accounts for more than 20% of new cases across the United States and “is likely to be our dominant strain here in the next couple of months,” according to Chicago Public Health Commissioner Dr. Allison Arwady. 

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Overall case counts have bottomed out across Illinois as 69% of eligible residents have gotten at least one vaccine dose, but Gov. J.B. Pritzker is pleading for remaining unvaccinated residents to get a life-saving jab because Delta surges in other countries “are a harbinger of what could happen here.”

It’s hard to say how bad a wave of Delta variant cases could get, but experts say the solution is simple: Get more shots into arms. 

Here’s a quick rundown of the latest focus of the pandemic, why experts are so concerned about it, and what it means for Illinois residents:

Where did the Delta variant come from?

It was termed the B.1.617.2 variant when it was first detected late last year in India, where it now makes up the vast majority of cases in that nation’s ongoing, devastating surge. 

It’s one of the thousands of variants that form through genetic mutation while the virus has replicated billions of times, according to Dr. Michael Angarone, an associate professor of medicine and infectious disease specialist at Northwestern Medicine. 

“As they replicate, that genetic material makes mistakes. It’s like if you type too fast, you’re going to miss a letter,” Angarone said.

Why is it dangerous?

Most variants are inconsequential, but some — like Delta — have proven to spread more easily. That’s what landed it on the list of several “variants of concern” highlighted by the U.S. Centers for Disease Control and Prevention. 

The Delta variant is unique because its so-called spike proteins allow it to more strongly latch onto cells in the respiratory and circulatory systems, Angarone said. 

The previously identified U.K. variant of the virus, which now makes up the majority of cases in the U.S., was about twice as infectious as the original form of the virus that swept the globe. The Delta variant could be up to 60% more infectious on top of that. 

“It spreads so easily, even potentially outdoors,” said University of Chicago epidemiologist Dr. Emily Landon. “It’s a huge problem for unvaccinated individuals.”

Angarone said experts are most concerned about a variant springing from a variant, which hasn’t yet happened on a large scale. “That’s when you start to get big changes in how the virus operates — can it bypass the vaccine immunity?”

So do COVID-19 vaccines protect against the Delta variant?

Yes, though they’re slightly less effective against it. Research has shown the Moderna and Pfizer vaccines are about 88% effective in preventing Delta cases, compared to 95% efficacy against the original strain of the virus. Another study suggested a similarly slight decrease in effectiveness for the Johnson & Johnson vaccine. 

“Either way, the vaccines are still going to help protect people from ending up in the hospital,” Landon said. 

Does the Delta variant make people more sick?

Some research has suggested the strain causes more severe symptoms and potentially a new one — hearing loss — but that’s still being studied. 

How many Delta cases have been detected in Illinois?

The Illinois Department of Public Health has identified 103 cases, but that’s only a sliver of the actual total. Just a small fraction of positive cases are evaluated to see if they’re a variant case. From that figure, experts can extrapolate that there are “way more cases,” Landon said, likely thousands. 

“The question is, will it take a foothold? Probably, among unvaccinated individuals,” she said. 

I’m fully vaccinated. Should I be worried?

Probably not, unless you’re in a largely unvaccinated community that sees a severe outbreak. 

That means it’s unlikely there’ll be a massive statewide surge in cases like the early months of the pandemic, not to mention the vicious resurgence Illinois suffered last fall.

Dr. Emily Landon of the University of Chicago.

Dr. Emily Landon of the University of Chicago.


“The vaccines are the walls that keep things contained,” Landon said. “But can one community become completely decimated by the Delta variant, in a neighborhood, in a church? Absolutely. Some areas are going to blow up. Will it overwhelm our health care system? Probably not.”

Angarone said even with the dangerous variants, COVID-19 will more likely end up “kind of like influenza, with a substantial number of people who get really sick, but nowhere near what we saw in early and mid periods of the pandemic.”

“What’s probably going to happen is we have enough immunity to protect most people, but see patches of outbreaks. But this pandemic has taught us that our crystal ball predictions are often wrong,” Angarone said. 

How the Delta virus plays out in the U.K. over the next few weeks “will be telling,” he added. 

I’ve already recovered from COVID-19. Should I be worried?

Very much so, if you’re not vaccinated. “These specific variants are especially suited to overcome immunity from a recovery,” Landon warned. “You’re certainly less protected.”

Does this mean I should keep masking up, even though the CDC has said it’s generally OK for fully vaccinated people to go maskless?

You’re not required to in Chicago or elsewhere in Illinois in most situations — but it couldn’t hurt. 

The World Health Organization updated its guidance last week recommending vaccinated people keep wearing masks to help stem the Delta spread, but Arwady, Chicago’s health commissioner, said the city is sticking with the looser CDC guidelines because the virus is “in very good control locally, even with the Delta here.”

Landon said there’s “no black and white when it comes to prevention, but if we all wore masks inside, it would be much less likely to spread. I think wearing masks inside would be prudent right now. It’s probably not essential, but I wouldn’t throw away your mask yet. Keep thinking about your fellow man.”

What else should I do to help keep the Delta variant at bay?

The golden rules of the pandemic still stand. 

“We have to use our sense of what we’re doing and who we’re going to be around,” Angarone said. “Wearing a mask and keeping distance — it’s still very helpful and will apply until we get this completely under control. And our most powerful tool is getting more people vaccinated.”

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