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COVID Cases Among Vaccinated Are Rare But Rising As Delta Variant Spreads In St. Louis Area

St. Louis County workers are vaccinated with the Pfizer vaccine at the mass vaccination site located on the campus of St. Louis Community College - Florissant Valley.
File Photo / David Kovaluk
St. Louis Public Radio
A health worker prepares a dose of COVID-19 vaccine at a clinic earlier this year in north St. Louis County. Health officials say more vaccinated people are testing positive for the coronavirus, but the vaccine is keeping them from getting severely ill.

More people who have received the COVID-19 vaccine are testing positive for the coronavirus than earlier this year, though such cases remain relatively rare, St. Louis County officials said Wednesday.

The more contagious delta variant and widespread transmission of the virus in the St. Louis region put even fully vaccinated people at risk, officials said.

“Because the delta variant is so contagious, there are so many more particularly unvaccinated people who are becoming infected and getting ill and transmitting infections,” said Dr. Steven Lawrence, an infectious disease specialist at Barnes-Jewish Hospital.

“When there is constant exposure over and over, even a lower-likelihood event such as a vaccinated person getting infected becomes more likely to happen if there are multiple, multiple exposures,” he said.

In St. Louis County, vaccinated people are catching the coronavirus at the rate of about 14 cases per 100,000 residents a day. That’s up from three cases per 100,000 residents a day in early July.

The rate among unvaccinated people in the county is approximately 39 per 100,000 residents each day.

Even if more vaccinated people are testing positive, they’re largely staying out of the region’s hospitals. In St. Louis area health systems, 84% of hospitalized COVID-19 patients are unvaccinated, said officials from the St. Louis Metropolitan Pandemic Task Force.

Many of the vaccinated patients are immunocompromised or hospitalized for other illnesses, said Dr. Clay Dunagan, task force leader.

The number of patients hospitalized in task force hospitals is four times what it was at the beginning of summer and as high as it was in February, before the vaccine was widely available, Dunagan said Tuesday.

That rate of increase is not sustainable, he said. "These facts are shocking and disheartening as we think about the preventability of cases we've seen.”

The virus is so prevalent in the region that it’s likely a typical person in St. Louis will come into contact with an infected person during grocery shopping or other daily activities, said Spring Schmidt, St. Louis County Department of Public Health deputy director.

“We do not mean for any of this data to be presented to instill fear. But it should instill caution,” she said. “It isn't just enough to be vaccinated in the current level of community transmission.”

To protect themselves and their loved ones, people should seek COVID-19 vaccines, minimize exposure and continue to wear masks, Schmidt said. That’s especially important as the delta variant is shown to be as transmissible among children, who cannot receive the vaccine, as it is among adults.

Health experts say the number of cases in vaccinated people makes up a very small percentage of total new cases.

A national study from the Kaiser Family Foundation showed less than 1% of people who were vaccinated later tested positive in states that reported such data. In all states that track cases in vaccinated people, they made up less than 1% to about 6% of overall coronavirus cases.

“Cases are one thing, but the vaccines still work as they were found to work in the clinical trials and the real world,” said Jen Kates, Kaiser Family Foundation vice president and one of the study's authors. “They prevent almost all the hospitalizations and fatalities.”

However, health experts say continued vaccination efforts are crucial, because the vaccine may not be as protective if future variants are allowed to develop and spread.

Follow Sarah on Twitter: @petit_smudge

Sarah Fentem is the health reporter at St. Louis Public Radio.