CHICAGO (WLS) -- Windy City Live executive producer Hank Mendheim returned from a Cape Cod vacation in July only to learn a few weeks later he and his friends would become part of CDC history.
"There were 10 people in our group in Cape Cod, and seven out of 10 tested positive for COVID," he said. "And we were all vaccinated."
The breakthrough cases caused by the delta variant in Provincetown, Mass., led the CDC to revise indoor mask recommendations last week.
"The delta variant is different, we are seeing the same amount of virus in vaccinated and unvaccinated individuals," said Dr. Khalilah Gates, pulmonary and critical care specialist at Northwestern Medicine.
Dr. Gates said that means that unlike previous variants, vaccinated people can transmit COVID but most of the breakthrough cases do not lead to hospitalizations or death.
"No one get severely sick, I only had a cough, lost my sense of smell and taste for five days, and I think had I not gotten the vaccine it could have been far worse," Mendheim said.
In Illinois, less than 2.5% of breakthrough cases led to hospitalization and death. In Chicago, 99.9% of vaccinated residents have not been diagnosed with COVID-19.
"So, were the vaccinated patients who have underlying immunocompetent status or were they on medication that cause their immune systems to not work as well?" Gates wondered.
She said the bottom line is the vaccines are working, none are 100%, and similar to Mendheim and his friends, most of the breakthrough cases are not causing serious illness or death.