Katlin Stupegia of MobileVax holds a vial of Johnson & Johnson's Janssen COVID-19 Vaccine at a special COVID-19 vaccination event with live performances for arts & culture workers held at Theater Wit in Lakeview on May 21, 2021. Credit: Colin Boyle/Block Club Chicago

CHICAGO — The chance of having a breakthrough coronavirus infection could be as low as less than one in 10,000 in Chicago, according to a new estimate.

The estimate, coming from a New York Times analysis, highlights how well fully vaccinated people are protected against the virus. A breakthrough case is when a person who is at least 14 days past their final COVID-19 vaccine dose becomes sick with the virus.

The analysis estimates the average vaccinated American has a one-in-5,000 shot per day of getting a breakthrough case. But that chance is even lower for people who take safety precautions or live in highly vaccinated areas.

In Chicago, where the COVID-19 outbreak is more under control than in other parts of the country, the chance of a vaccinated person getting a breakthrough case is probably less than one in 10,000 per day, according to the report.

And officials have repeatedly emphasized that the vast majority of people who do experience a breakthrough case will only have a mild case, as the vaccines still widely protect against severe illness and death.

“Delta really has changed the course of the pandemic,” according to the Times analysis. “It is far more contagious than earlier versions of the virus and calls for precautions that were not necessary a couple of months ago, like wearing masks in some indoor situations.

“But even with Delta, the overall risks for the vaccinated remain extremely small.”

Dr. Allison Arwady, head of the Chicago Department of Public Health, has said 95 percent of Chicagoans hospitalized with and dying from COVID-19 recently are not vaccinated.

The doctor has urged all people to take precautions, like wearing a mask indoors in public, to prevent the spread of COVID-19.

But officials have urged unvaccinated people to take even stricter precautions since they’re more at risk of catching, becoming severely sick from and transmitting the virus. Unvaccinated people should avoid traveling in the United States, for example, according to the city’s recommendations.


• In Illinois, about 6.8 million people — or 53.44 percent of the state’s 12.7 million people — have gotten all their COVID-19 vaccine shots, according to state data.

• Across the state, 23,613 vaccine doses are being administered per day, based on a seven-day rolling average.

• Illinois and Chicago have administered at least 14,086,690 vaccine doses of the 16,570,415 provided to them.

• City data shows more than 1.5 million Chicagoans — or 56 percent of all residents — are fully vaccinated. About 61.4 percent of all Chicagoans have gotten at least one shot.

COVID-19 vaccinations are free and do not require insurance. Anyone can call the city’s coronavirus hotline at 312-746-4835 to get more information on how and where to get vaccinated in their community.

The numbers:

• Sixty-six Illinoisans were reported dead from COVID-19 since Friday.

• At least 24,133 people have died from COVID-19 in Illinois, and another 2,564 deaths are probably related to the virus, according to the state.

• The state reported 12,051 cases since Friday. That brings the total number of confirmed cases in Illinois up to 1,550,375.

• Since Friday, 303,278 tests were reported statewide. In all, 29,481,168 tests have been reported in Illinois.

• Illinois’ seven-day positivity rate was at 4.5 percent. The figure represents the percentage of people testing positive among recent tests. It was at 5 percent Friday.

• Illinois’ seven-day test positivity rate, which measures the percentage of tests that were positive, was at 5.1 percent. It was at 5.4 percent Friday.

• As of Monday night, 551 people with COVID-19 were in the ICU and 300 people with COVID-19 were using ventilators in Illinois.

• In Chicago, four deaths were reported since Friday. There have been at least 5,661 deaths from COVID-19 in Chicago. The city is seeing an average of three deaths per day, unchanged from the week prior.

• Chicago has had 1,704 confirmed cases reported since Friday. It’s had a total of 307,329 confirmed cases. An average of 486 confirmed cases are being reported per day, a 1 percent increase from the week prior.

• At the same time, testing has decreased 2 percent since a week ago.

• Chicago’s positivity rate was at 4.2 percent, down from 4.3 percent the week prior.

Block Club Chicago’s coronavirus coverage is free for all readers. Block Club is an independent, 501(c)(3), journalist-run newsroom.

Subscribe to Block Club Chicago, an independent, 501(c)(3), journalist-run newsroom. Every dime we make funds reporting from Chicago’s neighborhoods.

Already subscribe? Click here to support Block Club with a tax-deductible donation. 

Listen to “It’s All Good: A Block Club Chicago Podcast” here:

kelly@blockclubchi.orgnnkelly@blockclubchi.org Twitter @BauerJournalism