CHICAGO — For people who contracted COVID-19 during earlier omicron surges, doctors have some unwelcome news: You are again susceptible to catching the virus.
Two new variants of the virus appear to more easily evade immune protection from prior infections, meaning even some who have recovered from a case of COVID-19 in recent months may become a clean slate for the virus. The vaccines still remain effective in largely preventing hospitalizations and death, doctors say.
The variants in the omicron family, BA.5 and BA.4, together are now the dominant strains in Illinois and across the country, according to medical experts and data from the Centers for Disease Control and Prevention.
“For right now, everybody is basically susceptible to this,” said Dr. Emily Landon, an epidemiologist at the University of Chicago School of Medicine.
With the new variants circulating, doctors still recommend people wear masks indoors and ensure they are up to date on booster shots. The COVID-19 booster remains an underutilized resource, with only about 34% of people 5 and over having received the third shot, according to the CDC.
People should also consider masking during crowded outdoor events as well, doctors said, such as the upcoming Lollapalooza music festival from July 28 to 31.
“People have gotten it in their head that being outside is magic,” Landon said.
She noted that cases will likely rise after Lollapalooza, but added that fact alone doesn’t make it unsafe to hold it, as the festival is a voluntary event. She implored attendees, though, to take care of their impact on others after the events by testing themselves, staying home if they feel sick and avoiding immunocompromised people.
“You can make your choice about whether you go to Lollapalooza,” Landon said. “The grocery store is a completely different thing.”
As of last week, about 72% of cases in the Midwest were either the BA.5 or BA.4 strain, according to CDC data, which groups Illinois with Indiana, Ohio, Wisconsin, Michigan and Minnesota. Nationwide, the new variants make up about 70% of cases.
Most of the cases are the BA.5, which appears to be outcompeting the similar BA.4, experts say.
The new variants have “a few more mutations in the spike protein” that make them more resistant to antibodies, according to Dr. Egon Ozer, an infectious disease specialist at Northwestern Memorial Hospital.
Ozer said early data show that the BA.5 had reinfected people who contracted earlier variants of COVID-19 in the winter or early spring, who for a time had carried some immunity guarding against a new infection.
“Every infection is an opportunity (for the virus) to adapt further and to overcome new defenses,” Ozer said. “It’s probably a bit of an arms race over time in terms of the virus changing and us changing the vaccine.”
Pfizer and Moderna have been working on a booster shot designed specifically with omicron in mind.
New cases in both Illinois and Chicago have gone down since May, when a prior strain of omicron caused a spike in infections, but doctors note that the prolific use of at-home tests means official case numbers are likely undercounted. The CDC has designated Cook County as having a medium level of community transmission.
Chicago Public Schools’ in-school COVID-19 testing program resumed last week for those participating in summer session. Forty-two people tested positive among 2,670 tests administered last week, according to online CPS data. The 1.6% positivity rate is higher than the 1% positivity CPS recorded days before the school year ended on June 14. The district is reporting 200 adult COVID-19 cases and 32 student cases so far this summer.
Even though the vaccines, along with new therapies that treat COVID-19, increasingly make the virus less deadly upon infection, its ability to continue to reinfect the population at rapid rates raises the specter of continued disruptions as the U.S. continues to face supply chain issues.
“There’s always economic costs and issues with health care when people are having to stay home from work,” said Dr. Jonathan Martin, an infectious disease physician with Cook County Health. “I know there are people out there who think the pandemic is over. I assure you, the virus is not done with us yet.”
And much is still unknown about COVID-19′s long-term health impact, doctors say, with evidence mounting that prior infections can put people at higher risk for other medical conditions.
“I don’t think people are taking it quite as seriously as they should,” Landon said.
Doctors stress that the more the population reduces infections, the fewer chances the virus has to continue to mutate.
“There’s still really good reasons to avoid getting COVID,” Landon said.
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(Chicago Tribune’s Tracy Swartz contributed.)
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