At least 151 people have died and more than 500 have been hospitalized in Illinois due to COVID-19 in "breakthrough" cases after they were fully vaccinated, according to state health officials.
What is a breakthrough COVID case, how common are they and how are they being tracked? Here's what you should know:
What is a breakthrough COVID case?
A vaccine breakthrough case occurs when a person tests positive for COVID-19 after they've been fully vaccinated against the disease.
A person is considered “fully vaccinated” two weeks after receiving the second dose of either the Pfizer or Moderna COVID vaccine, or two weeks after receiving the single-dose Johnson & Johnson vaccine.
How many breakthrough COVID cases has Illinois had?
According to data updated Wednesday by the Illinois Department of Public Health, 151 people in Illinois have died due to COVID-19 or complications after being fully vaccinated. That figure equates to 2.2% of COVID-19 deaths in the state since Jan. 1, officials said.
At least 563 fully vaccinated people have been hospitalized in Illinois, IDPH said.
The state only reports breakthrough infections among those who have been hospitalized or died, following guidance from the Centers for Disease Control and Prevention, IDPH said.
The state does not publicize the number of residents who tested positive after being fully vaccinated but did not die or require hospitalization in order to "help maximize the quality of the data collected on cases of greatest clinical and public health importance," IDPH's website reads.
How many total breakthrough cases have occurred in the US?
The CDC transitioned from monitoring all reported breakthrough cases to only reporting hospitalizations or deaths on May 1, the agency says.
That means the total number of breakthrough cases at this point is not made publicly available, but federal health officials did track all breakthrough cases from January of this year through April 30, 2021.
The CDC says that in that time period, a total of 10,262 breakthrough COVID cases were reported in 46 U.S. states and territories. About 63% of those cases were in women, with the median patient age at 58 years.
The CDC says 27% of those breakthrough infections were asymptomatic, while 2% died.
About 10% of those breakthrough cases were hospitalized, officials said, but among those hospitalized, 29% were asymptomatic or hospitalized for a reason other than COVID-19.
Vaccination may make COVID-19 less severe for breakthrough cases
"There is some evidence that vaccination may make illness less severe for those who are vaccinated and still get sick," the CDC says.
One Chicago man who contracted COVID-19 earlier this month after getting vaccinated in March said his symptoms were "more intense than I expected them to be," he's grateful for his vaccine.
"The vaccine still worked for me because it kept me out of the hospital - and that's the most important thing - and it kept me alive," Robert Flinn said. "I'm confident that I won't end up there. Hopefully I don't."
Another Chicagoan who tested positive after a group vacation to Massachusetts said that the symptoms were mild for him and his friends, which he credited the vaccine for.
"It's like a really nasty cold," Robert Coy said. "You'll get a bit of a cough, maybe, and you just feel tired and it's not fun, but I will say it's definitely a lot less severe than I would have expected. Had I gotten this last year before I'd been vaccinated... I've seen people go through way, way, way, way worse."
How common are breakthrough COVID cases?
While breakthrough cases have been considered rare, they are possible and even "expected," per the CDC. Experts have said that while the vaccine itself cannot give you the virus, it is also not 100% effective at preventing the virus entirely, though those who receive the vaccine are far less likely to be hospitalized or die from it, data shows.
"COVID-19 vaccines are effective and are a critical tool to bring the pandemic under control," the CDC's website reads. "However, no vaccines are 100% effective at preventing illness in vaccinated people. There will be a small percentage of fully vaccinated people who still get sick, are hospitalized, or die from COVID-19."
The CDC says this is true of all vaccines: not one prevents illness 100% of the time.
Illinois' top doctor said Tuesday that breakthrough cases of COVID-19 in fully vaccinated residents are a "unicorn" as she again urged those who have not yet gotten vaccinated to do so.
"These vaccines are truly effective," IDPH Director Dr. Ngozi Ezike said. "You know, everyone has heard of a case or two of someone who had a breakthrough infection or breakthrough hospitalization, but it is, that is so far the unicorn, that you need to focus on the people who are not vaccinated, they're the ones filling up the hospital as COVID patients."
Cases are surging in areas of lower vaccination rates, officials say
The recent surge of COVID-19 cases in certain parts of the state have been found in areas of lower vaccination rates, Ezike said.
"There is a very clear connection between where those case rates are growing the fastest and how well that area is vaccinated, i.e. the more highly vaccinated areas are having lower case rates," she said.
She noted that the growing delta variant has a higher transmissibility that impacts more people at a time than previous variants. Within weeks, Ezike said Illinois has seen COVID cases double statewide.
Studies have shown that the delta variant spreads approximately 225% faster than the original strain of the virus. Studies have also shown that once a person catches the delta variant, they likely become infectious sooner, and that the virus grows more rapidly inside a person’s respiratory tract.
Areas of western and southern Illinois are seeing increases in positivity rates and coronavirus-related hospitalizations in recent weeks, continuing a recent trend that’s seeing COVID metrics slowly on the rise in many areas, particularly those bordering Missouri.
As the delta variant continues to spread, experts are continuing to push for more Americans to get the COVID vaccine. All three of the vaccines currently authorized for emergency use by the FDA, have shown to be largely effective against preventing serious illness and death due to COVID, and all three companies say that their vaccines are showing promise in preventing those outcomes with the delta variant as well.