Of the nearly 3.2 million people fully vaccinated against COVID-19 in Illinois, 771 have nevertheless contracted the disease and 13 have died, Illinois Department of Public Health officials report.
The number is a tiny fraction of the disease’s total toll, with 1,296,381 known cases and 21,630 deaths among Illinoisans since the start of the pandemic.
Citing confidentiality reasons, IDPH officials would not comment on whether the 13 who died had anything in common or had health problems that could have made the vaccine less effective.
Recently, researchers have found that individuals who were already suffering from compromised immune systems or who were taking strong immunosuppressants were more susceptible to serious consequences from the virus, even when fully vaccinated.
“What we don’t know is the effectiveness of these vaccines in immunocompromised individuals,” said Dr. Jonathan Pinsky, medical director of infection control and prevention at Edward Hospital in Naperville. “We have to learn from those numbers and find out more about those cases to determine what the threat is.”
Nationally, according to data from last week in a recent NPR report, about 5,800 cases called “ vaccine breakthroughs ” have been reported to the U.S. Centers for Disease Control and Prevention. Among those breakthrough cases, federal officials reported 74 deaths.
People are considered fully vaccinated when they are two weeks after their last dose of vaccine. In Illinois, 3,182,010 people meet that standard, nearly a quarter of the population, according to IDPH figures.
Those who become ill after being fully vaccinated represent less than 0.03% of that population, or one in 4,127 fully vaccinated people.
Of those vaccinated who were infected, 29 were ill enough to be hospitalized. That’s one in every 109,724 fully vaccinated individuals. Those who died represent one in 244,770 fully vaccinated people.
Clinical studies of the COVID-19 vaccines in the United States have shown efficacy of at least 94% in preventing serious illness and death and about 80% in preventing COVID-19 infection.
Pinsky was concerned about how some of the breakthrough cases were counted in fully vaccinated individuals. Since symptoms usually appear a few days after infection, it is possible that someone diagnosed after the two-week threshold may actually have been infected before the vaccine was fully effective.
“There is the potential for fewer breakthrough cases the further you are from that second dose,” he said.
All told, 166,885 additional doses of COVID-19 vaccines went into the arms of Illinois residents and workers Thursday, IDPH officials reported. It is the second highest number of vaccines that Illinois suppliers have administered in one day.
The vaccine doses administered in Illinois are 7,779,290, with 3,453,704 in suburban Cook, DuPage, Kane, Lake, McHenry and Will counties.
IDPH reported 3,866 new cases of COVID-19 and 21 more deaths from the respiratory disease on Friday.
Hospitals in Illinois treated 2,058 patients for COVID-19 on Thursday, 468 of them in intensive care.
The state’s seven-day mean positivity rate is 4.2%. It stayed at that level for three days in a row. An important measure used in measuring levels of infection, case positivity tracks the percentage of new cases derived from a battery of tests.