CT Coronavirus Breakthrough Cases On Rise: Yale Study

CONNECTICUT — If you were getting the sneaking suspicion that the number of COVID-19 breakthrough cases — fully-vaccinated people who still catch the virus — is growing, you were not wrong.

A study from Yale University, released last week and published in Lancet Infectious Diseases, confirms that breakthrough cases are happening more frequently in Connecticut.

The researchers studied hospitalized patients in the Yale New Haven Health System who tested positive for COVID-19 during a 14-week period between March and July 2021. Of that group, 54 were fully vaccinated.

"These cases are extremely rare, but they are becoming more frequent as variants emerge and more time passes since patients are vaccinated," said Hyung Chun, associate professor of medicine (cardiology) at Yale and senior author of the study.

The scientists went looking for some common themes, and found them. The breakthrough patients in the study tended to be older, between 65 and 95 years old, with a median age of 80.5. They also had preexisting comorbidities, such as Type 2 diabetes and cardiovascular disease. A subset of patients was also on immunosuppressive drugs that may affect vaccine efficacy, according to a news release from Yale.

It's worth noting that many of the patients with severe breakthrough infections in Chun's study were hospitalized before the dominance of the delta variant in the state. Additional research will be needed to determine the impact of the Delta variant on the rate of breakthrough COVID-19, he said.

31% Of New Connecticut COVID-19 Cases Are Fully Vaccinated: DPH

Of the 2,207 coronavirus cases recorded by the Connecticut Department of Public Health in the most recent 7-day reporting period, 1,521 were not fully vaccinated. The remainder, 686, or 31.1 percent, had completed their vaccine series.

DPH is also reporting that as of Thursday, 9,875 cases breakthrough cases of COVID-19 in the state have been confirmed, up from 8,617 last week. Seventy coronavirus-related deaths have occurred among those breakthrough cases, up from 65 the previous week.

These deaths represent 7.1 percent of all COVID-19 deaths since Feb. 9, according to the DPH report. Nearly 76 percent of the fatalities have been among patients 75 years of age and older.

From the start of the pandemic through Wednesday, of the more than 2.2 million people in Connecticut have completed their vaccine series, 0.43 percent have contracted the virus, up 0.05 percent from last week's report.

Nationwide, as of Sept. 9, 2,675 fully vaccinated people have died as a result of the virus, and 87 percent of them have been age 65 or older, according to the Centers for Disease Control and Prevention.

The charts above and below also shows the "relative risk," or the difference in risk when comparing rates between vaccinated and unvaccinated persons.

Although coronavirus deaths in Connecticut have declined markedly since February, it is important to note that death — and hospitalization — rates have consistently been higher among unvaccinated persons compared to fully vaccinated persons.

According to DPH, unvaccinated residents have a 5-times higher risk of being infected with, and being hospitalized as a result of, COVID-19, compared to people vaccinated against the virus. Their risk of dying is seven times greater.

This week, the state Department of Public Health has reported just 22 new deaths. Last week, DPH reported 39 news deaths, up from 25 the previous week. To date, 8,416 Connecticut residents have died from COVID-19-associated illness.

The number of COVID-19 patients in facilities throughout the state reported on Friday was 364, up 10 beds overnight, but down one from the previous weekend.

The daily coronavirus positivity rate has averaged 3.17 percent for the past two weeks, down just under a quarter point compared to the previous 2-week period. On Friday, DPH reported it as 2.73 percent, on the basis of 625 new confirmed COVID-19 cases out of 22,894 tests.

See Also: Updates On COVID-19 Red Zones, Vaccination Rates In Connecticut