Unvaccinated? Beware: As state loosens restrictions, the risk of a serious COVID-19 infection may be higher than it was last summer.

Illinois dropped many of its remaining pandemic restrictions Friday, but public health data shows two different realities lie ahead for people as that reopening begins.

For those who are fully vaccinated, the threat of a serious infection is largely (but not entirely) over. Of more than 5 million fully vaccinated Illinoisans, state data shows 413 later got sick enough from the coronavirus to be hospitalized.

But for people who haven’t gotten the shot, the risks of catching COVID-19 remain — and researchers are worried about how this group will fare this summer.

A Tribune analysis of state and federal data shows that for those not fully vaccinated, hospitalization and death rates in Illinois have been notably higher in recent months than they were last summer, when vaccines weren’t available but coronavirus cases had plummeted.

Take hospital admissions. During the last four weeks, the hospitalization rate for those not fully vaccinated was roughly 50% higher what it was during one of the mildest four-week periods last summer. And death rates for this group are roughly double last summer’s rates.

While the odds of dying or being hospitalized remain low even for those unvaccinated, doctors say the virus remains a threat to those who haven’t gotten a shot, despite the overall number of cases dropping.

“Just because the numbers are low, it doesn’t necessarily mean you’re not going to contract COVID if you’re not vaccinated,” said Dr. Shikha Jain, an oncologist who also helps run the advocacy group Illinois Medical Professionals Action Collaborative Team.

The risk for unvaccinated people may be growing as people become less careful about taking precautions, amid the reopening, said Jain, who’s also an assistant professor of medicine at the University of Illinois Cancer Center in Chicago. She’s had about half a dozen patients catch COVID-19 after deciding not to get vaccinated, including three or so in the last month.

The data remains concerning to some who have studied the virus’ path over the past year, such as Jaline Gerardin, a Northwestern University assistant professor of preventive medicine. She said that those still left to be vaccinated are generally younger and healthier than the population as a whole. So it’s a troubling sign if this younger and healthier group is still being hospitalized and dying at rates above what the entire state saw last summer.

In addition, the pandemic statistics that the public focuses on — the number of cases, hospitalizations and deaths — don’t include a breakdown of the differences between the fully vaccinated and those who aren’t. That can hide the dangers to unvaccinated people, said Nigel Goldenfeld, a University of Illinois physics professor who has worked with university colleague Sergei Maslov to develop COVID-19 forecasts.

“To see the epidemic trends, it is essential to separate out the fully-vaccinated population from the unvaccinated,” Goldenfeld said.

Here’s what we know:

Reopening

Effective Friday, Gov. J.B. Pritzker revised his emergency orders to lift capacity limits, social distancing requirements and health screening mandates. Masks are still required on public transportation, inside schools and day cares, and in health care settings, and those not fully vaccinated are asked to wear masks in public (unless outdoors and 6 feet away from others), while still avoiding crowds and poorly ventilated areas.

The reopening follows a 15-month roller coaster of two major waves of COVID-19 infections in Illinois, massive job losses from lockdowns and a running death tally the state calculates at roughly 23,000, though experts have blamed even more deaths on the pandemic.

Since March 2020, the Pritzker administration set up various benchmarks that served as trigger points of when to ramp restrictions up or down, with the goal of making sure the health care system isn’t overwhelmed and avoiding deaths. Illinois is meeting the governor’s metrics to reopen.

One key metric: declining hospitalizations. Statewide, the number of people hospitalized each day with COVID-19 has dropped in the past month from nearly 2,000 during a brief third surge to less than 1,000. To put that in context, last fall, the figure peaked at 6,000, and the fear then was that hospitals could become overwhelmed.

Pritzker also set reopening benchmarks for vaccinations: at least 50% of those 16 and older getting at least one shot (more than 60% have received a shot), and at least 70% of those 65 and older getting at least one shot (more than 80% have done so).

Overall, at least 5.2 million Illinoisans are considered fully vaccinated, defined by federal health officials as having gotten a final shot at least two weeks ago, to give their bodies time to build up maximum immunity.

Nearly 1.4 million residents are partially vaccinated, while another 4.3 million are old enough to qualify but have yet to get a shot. Another nearly 1.9 million others are too young to qualify for now.

Breakthrough cases

The risks for vaccinated people are not zero, but still far lower than even the mildest periods of the pandemic.

The state measures that risk through so-called breakthrough cases documented among those vaccinated. As of Wednesday, the Illinois Department of Public Health documented 413 breakthrough infections serious enough that they led to hospitalizations, with 106 deaths.

Those small numbers show how well the vaccine has worked. A Centers for Disease Control and Prevention study released Monday found that two-dose vaccines reduced the risk of infection by 91%, while limiting the seriousness of the disease for those rare cases of infection.

That also is borne out in the Illinois data analyzed by the Tribune.

The Tribune compared federal hospitalization data on overall admittances for known COVID-19 against state breakthrough data on hospitalizations. To smooth out the normal ups and downs of statistics, the analysis looked at four-week periods from last summer, when federal figures first became available.

The analysis covered mid-March to early June, the period for which state public health officials published breakthrough data, and midsummer 2020 through mid-January, when enough data was available and before Illinois’ vaccination program had produced anyone fully vaccinated. The numbers show the rate of infections is far lower now among those fully vaccinated than it was even during last summer’s lull in COVID-19 cases.

At the tamest part of the pandemic last summer, when nobody could be vaccinated, the average daily rate of hospitalizations was 0.9 per 100,000 residents. In the most recent four-week period that could be studied, through Wednesday, the rate for those fully vaccinated had dropped to 0.2.

So what’s the worry?

And then there’s the risk for the rest of Illinoisans: those who haven’t had a drop of vaccine to those who’ve gotten shots but are still not two weeks beyond the final one. For now, that’s a majority of the state’s population.

The data offers a picture that’s a little more uneasy for this group. Their rates of hospitalizations for COVID-19 were higher than last summer’s lull.

During the most recent four-week period, the average daily admittance rate was 1.4 per 100,000 in that group. That’s about 50% higher than last summer, although still lower than a rate of 4.3 for all Illinoisans during the height of the fall-winter surge.

The hospitalization rates for those not fully vaccinated, although dropping, still trouble Gerardin, the Northwestern researcher.

After reviewing the Tribune’s analysis, she said that one of her concerns is that those left to be fully vaccinated are generally younger and healthier. So if that group is getting sick enough to need hospitalization, and at higher rates than the broader population earlier in the pandemic, that shows how dangerous the virus remains and “actually reflects an even bigger disparity.”

That risk was shown in a recent CDC study which found that across the country, COVID-19 hospitalization rates among adolescents, although still low, had roughly doubled from March to April.

Another window into the danger is through Illinois’ death data.

During last summer’s infection lull, when everyone was unvaccinated, the average daily death rate was less than 0.15 per 100,000 residents, peaking at about 1.04 during the fall-winter surge. In the most recent four-week period, the average daily death rate was nearly 0.30. That’s still less than the worst of the pandemic, but double the summer 2020 lull.

The state doesn’t publish more precise data on those not fully vaccinated, making it difficult to discern more details of those who have been more likely to be hospitalized or die.

The public health agency also declined to make officials available to answer questions about what the Tribune found, or how the agency itself may be studying the issue and adjust its efforts.

In an email, spokeswoman Melaney Arnold told the Tribune that, in general, the agency is processing “massive amounts of data” each day but lacks the capacity to study it deeply.

“IDPH is not a research agency, and while we do try to identify trends to inform decision, we are not able to conduct studies, especially during a pandemic,” she said. “Much of this research and study is being done at the national level, by universities, and by other public health research organizations.”

Publicly, the Pritzker administration has struck consistent themes as the governor prepares for a possible reelection bid: pushing for people to get shots and advising the unvaccinated to be more careful, all the while celebrating the overall decline in numbers and, more recently, the pending reopening for Illinois.

“I want people to have an incredible summer,” IDPH’s director, Dr. Ngozi Ezike, said last week on Illinois Public Media’s “The 21st Show.”

“I think we are seeing the lowest positivity (rate) that we’ve seen since we’ve even been recording anything related to positivity for COVID. So we are going to have a summer that will look similar to summers from 2019.”

Unknowns

Because of the limited data available, questions remain about the risk to different groups, such as those partially vaccinated.

Research shows benefits beginning two weeks after the first shot of the two-dose regimen, but the state doesn’t offer statistics on hospitalizations and deaths of those partially vaccinated. That’s a sizable number now — roughly 1 in 9 Illinoisans.

And without knowing that, it’s difficult to compute a risk rate for another large group: those who haven’t gotten any vaccine doses.

Other questions remain about the type of fully vaccinated people still getting seriously ill or dying. The state public health agency is weeks past a legal deadline to provide detailed breakthrough data as part of a Tribune public records request. The agency regularly has failed to meet legal deadlines to provide data and records during the pandemic.

That lack of data, in turn, makes it harder to calculate the risk rates by region, which vary in how many people are fully vaccinated. Nearly half of residents in the region covering DuPage and Kane counties are fully vaccinated, but less than a third are in the southern tip of the state.

Some good news: overall hospitalization figures for COVID-like symptoms (regardless of who’s been vaccinated) in all regions are seeing a drop from the spring rise in infections.

Still, trends could change as the state reopens. And U. of I.’s Goldenfeld cited the differing vaccination rates as a reason to study each region’s figures, and not just statewide totals, noting “the highly-vaccinated people in one region will hide the trends in the region with low rates of vaccination.”

“This is critically important at a time when the state as a whole is opening up, and highly infectious variants … are still spreading in Illinois,” he said.

jmahr@chicagotribune.com

dpetrella@chicagotribune.com

lschencker@chicagotribune.com

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