It’s been a month since new COVID-19 boosters arrived. About 10.5% of eligible Illinois residents have gotten them.

About 10.5% of people in Illinois eligible for new, updated COVID-19 boosters have received them in the month since they became available — a percentage that worries some doctors who fear a winter surge.

“I think this is not top of mind for people anymore, but possibly when the fall and winter surge happens people will feel more urgency,” said Dr. Mercedes Carnethon, a professor and vice chair of preventative medicine at Northwestern University Feinberg School of Medicine.

The updated boosters started going into arms in Illinois during the second week of September. The shots, made by Pfizer and Moderna, are called bivalent boosters because they’re designed to protect against COVID-19 broadly as well as against the omicron variants that are now dominant in the U.S.

Eligible people, over the last month, included individuals ages 12 and older, who completed their original vaccine series, as long as it had been at least two months since their last dose or booster shot.

Of all Illinois residents, ages 12 and older — including those who aren’t eligible for the updated boosters because they didn’t get previous COVID-19 vaccines or it’s been less than two months since their last shot — about 7.9% of the population has gotten bivalent boosters, according to the state health department.

On Wednesday, bivalent boosters were authorized for children ages 5 to 11 as well.

The 7.9% is a far cry from the number of Illinois residents who’ve received previous shots. Nearly 78% of Illinois residents ages 12 and older have completed their first two shots of the Moderna or Pfizer vaccines or gotten one shot of the Johnson & Johnson vaccine, since those were authorized.

About 865,000 doses of the bivalent booster shots had been administered in Illinois as of Wednesday.

Part of the reason more people aren’t rushing to get the boosters may be because they’re not as worried about COVID-19 as they once were. When mitigation measures faded earlier this year, many people began to feel more relaxed about COVID-19, Carnethon said.

“I think people think it’s not a big deal,” she said. “Much of that, really, is some false confidence because there are people who do get severely ill and there are people for whom you might not expect to have such a bad (illness) and they do.”

It’s also possible not everyone understands how this booster is different from the last one, said Dr. Shikha Jain, an associate professor at the University of Illinois and CEO and co-founder of the Illinois Medical Professionals Action Collaborative Team (IMPACT), an advocacy group of medical professionals.

Jain, who is a medical oncologist, said she’s seen many patients who didn’t know why they might need the updated booster.

“They were saying, ‘I got a booster months ago,’ ” she said.

Patients don’t know exactly who is eligible or when a person is eligible, she said. People must have completed the primary series of a COVID-19 vaccine to get the updated booster. People who got the previous versions of the COVID-19 booster shot can still get the updated one, as long as it’s been at least two months since their last dose.

If a person has just been sick with COVID-19, the Centers for Disease Control and Prevention says that person may (but doesn’t have to) wait three months to get the updated booster. Jain said she’d recommend a person who just had COVID-19 get it sooner than that — after symptoms are gone and a rapid, at-home test shows a negative result.

People also may think it’s not important to get the booster because COVID-19 isn’t as prevalent as it once was. Cook County and its surrounding counties are all now at low COVID-19 community levels, according to the CDC. Unlike during previous stretches of the pandemic, COVID-19 doesn’t seem to be sending nearly as many people to hospitals. As of Tuesday, there were 968 COVID-19 patients in Illinois hospitals — far less than the more than 7,000 who filled beds during the surge last January.

Jain, however, suspects that the number of overall cases may be higher than what the data shows because many people who have COVID-19 are likely testing only at home or not at all.

“I think, unfortunately, we’ve all gotten to a point now where we have COVID fatigue to the nth degree,” Jain said. “The thing that makes me the most sad is I see a lot of young healthy individuals that they’ve gotten so fatigued that they’ve stopped taking the precautions they were taking previously. They get COVID and they end up having symptoms for months.

“I think a lot of people are just tired of talking about COVID, tired of thinking about COVID and would like to pretend it’s not here anymore, and unfortunately, that’s not the way viruses and pandemics work,” she said.

Illinois Department of Public Health Director Dr. Sameer Vohra said about two weeks ago he was encouraged by the number of people who had gotten bivalent boosters at that point. He cautioned people not to let their guard down, even though COVID-19 numbers were declining.

“As we head into fall and face a potential surge in new cases, I urge everyone who is eligible to contact their health care provider or local pharmacy to get the updated booster AND their flu shot,” Vohra said in a news release.

Doctors are hopeful that more people will get the bivalent boosters now that they’ve been approved for children as young as 5. But, so far, children have been receiving COVID-19 vaccines at a lower rate than adults. About 39% of children ages 5 to 11 in Illinois are considered fully vaccinated, meaning they received the first two doses.

Illinois seniors have proven the most eager for the bivalent boosters, with 22.3% of eligible people in that group having received them. Only 3.8% of eligible youth ages 12 to 17 have gotten the bivalent boosters.

Disparities also exist between racial groups. About 6.7% of eligible Black Illinois residents have gotten the updated boosters, 4.3% of eligible Hispanic residents, 13.2% of eligible white people and 9.5% of eligible Asian residents.

lschencker@chicagotribune.com