CT has tracked 938 ‘breakthrough’ COVID cases among 2.4M vaccinated

Photo of Julia Bergman
Wilza Cordero, of Ansonia, receives her second COVID-19 vaccination shot from St. Vincent’s Medical Center nurse Mo Blees at the mass vaccination clinic on Sacred Heart University’s West Campus, in Fairfield, Conn. June 30, 2021.

Wilza Cordero, of Ansonia, receives her second COVID-19 vaccination shot from St. Vincent’s Medical Center nurse Mo Blees at the mass vaccination clinic on Sacred Heart University’s West Campus, in Fairfield, Conn. June 30, 2021.

Ned Gerard/Hearst Connecticut Media

Connecticut adults and older teens vaccinated against COVID-19 have had a 1 in 2,500 chance of having a positive test since the start of immunizations last December, according to a database provided by the state.

Those who were not immunized? They’ve had closer to a 1 in 6 chance of coming down with a recorded case of the illness, according to figures released by the state Department of Public Health Friday.

The department has tracked 938 so-called breakthrough cases of COVID-19 among people who are vaccinated. Of those, 160 people were hospitalized and 20 died, the new numbers showed.

Officials did not say whether any of those patients were fully or partially vaccinated and it’s unclear whether the 938 cases represent the full number of positive tests among people who have received vaccinations.

Still, the numbers paint a stark difference in the outcomes between people who have and have not rolled up their sleeves for an inoculation — and confirm a point underscored by public health officials: breakthrough cases are rare.

“No vaccine is perfect. No vaccine gives 100 percent immunity to infection, to disease, but these vaccines are highly effective,” said Dr. Albert Ko, a Yale epidemiologist who co-chaired Gov. Ned Lamont’s reopening committee last spring.

More than 2.1 million residents in Connecticut are fully vaccinated and 2.4 million residents have received at least one dose, out of 2.9 million eligible, giving the state one of the highest vaccination rates in the country.

Connecticut on Friday reported an additional 212 COVID-19 cases since Thursday for a daily positivity rate of 1.73 percent, and an additional 10 hospitalizations from a day earlier, the largest single-day jump since late April, for a total of 76.

The weekly positivity rate ticked up to 1.89 percent — the highest its been since early May. Gov. Ned Lamont said the state is watching hospitalization numbers closely but reiterated Friday that the precautions in place are adequate for the time being.

“I’m going to hold off because we didn’t even know what the delta variant was three weeks ago. We sure as heck know now, let’s let another couple, two or three weeks go by, let’s see what it looks like we’ll have a much better window of what the new school year is going to look like and I’m following hospitalizations very carefully as a key metric to make these determinations,” the governor said.

The COVID-19 mRNA vaccines developed by Pfizer-BioNTech and Moderna have shown to be 94 percent effective in reducing the risk of illness in fully vaccinated people, according to data from the Centers for Disease Control and Protection.

“What’s not actually counted is the people who are fully vaccinated, who have been exposed and are protected,” Ko said. “If we compare the risk of people who are vaccinated getting a breakthrough case to people who are unvaccinated getting sick, that risk is very small.”

The state has reported about 185,000 positive COVID-19 cases since it opened its first round of inoculations on Dec. 14, starting with health care workers and residents of long-term care facilities, vulnerable populations at higher risk of severe infection.

Of the 938 breakthrough cases, nearly a quarter were among people 75 and older, who also were prioritized for inoculations given they are at higher risk for getting sick and dying from COVID-19. Nearly 54 percent of the hospitalizations and 80 percent of the deaths affected people 75 and older.

National comparisons are not readily available. The U.S. Centers for Disease Control and Prevention stopped tracking all breakthrough infections starting May 1, to focus on investigating only those among patients who are hospitalized or die.

From January to April, one of every 10,000 vaccinated Americans had a recorded, positive breakthrough case, according to the CDC. The number who actually contracted COVID-19 may be significantly higher, as many went untested — especially since the vaccine causes cases to be less severe.

As of July 19, more than 161 million people in the United States had been fully vaccinated against COVID-19, and the CDC had received reports of 5,914 patients with breakthrough infections who were hospitalized or died.

The highly contagious delta variant, which has become the dominant coronavirus strain in the U.S. and in Connecticut, has fueled outbreaks among unvaccinated people. Health officials have said at this point in the pandemic the majority of those hospitalized and dying from COVID-19 are not vaccinated.

The rapid spread of the delta variant is prompting local governments and private businesses across the country to consider whether to institute vaccine mandates or reinstate protocols such as wearing masks indoors, even for those who are immunized, or delaying plans for employees to return to work.

Studies out of the United Kingdom and Israel, “which had the delta epidemic before us,” show that if someone is fully immunized, they have nearly the same level of protection against delta as other variants, Ko said.

But there was “marked decrease” in protection against delta among people who only had one dose of the vaccine, he said.

Health officials expect COVID-19 cases to continue to rise in Connecticut. Ko said he predict the surge will be much smaller than what the state experienced last winter, but added that the next couple of weeks will be telling as officials continue to monitor the trajectory of the delta variant.

If Connecticut experiences a spike in cases similar to what Provincetown, Mass., saw recently, then Ko said officials should consider whether to limit large gatherings, particularly indoors, and take precautions in schools in order for children to return for in-person learning such as requiring masks given children under 12 are not eligible to get the vaccine.

But, he said, there’s still time to make those decisions.

“What we’re going to learn over the summer is whether our vaccination rates now will dampen a large surge in cases such as we’re seeing in the south of U.S.,” Ko said. “We have time.”

Hearst Staff Writers Jordan Fenster and John Moritz contributed to this report.