Updated July 13, 2021 - 7:50 pm
Southern Nevada health officials sounded the alarm in June over a cluster of “breakthrough” cases of the coronavirus delta variant among vaccinated employees of a Las Vegas hospital.
At least 11 employees of Sunrise Hospital and Medical Center tested positive for COVID-19 after attending a party on June 7, according to Southern Nevada Health District emails obtained through records requests by the Brown Institute for Media Innovation’s Documenting COVID-19 project. The emails, which were shared with the Review-Journal, indicate that eight of the employees had been fully vaccinated in December and January, meaning that the virus had “broken through” the protection of inoculation.
Two other employees who were infected had received one dose of a double-dose vaccination. One was unvaccinated. At least 10 of the 11 had the delta variant, a more easily transmissible strain of the virus.
The cluster prompted health district officials to initially question whether doses of the temperature-sensitive vaccine given by the hospital to its employees might have been improperly handled or stored. This possibility was quickly dismissed.
“At the request of the health district, HCA Sunrise Hospital conducted a preliminary investigation of its vaccine administration and storage practices and found no evidence of improper storage or handling issues,” health district representative Stephanie Bethel said in an email.
‘No mishandling of the vaccine’
In a statement to the Review-Journal, Sunrise CEO Todd P. Sklamberg, said, “There was absolutely no mishandling of the vaccine at any time.”
In an email to the district, a Sunrise manager said that security surrounding vaccines had been “very tight.”
“Think ‘Lock/key armed guard,’” wrote Jennifer Sanguinet, director of infection prevention.
Sklamberg said in his statement that an outside gathering of employees triggered the illnesses.
“The source of the outbreak was an off-site private party on June 7 and all who tested positive are doing well and have returned to work,” he said.
“Although all were vaccinated, we want to acknowledge our colleagues recognized their own symptoms (similar to allergies or the common cold) and chose to get tested,” he said. “There were no exposures to our patients as our staff complies with all PPE (personal protective equipment) guidelines, masking at all times and wearing face shields with all patient encounters.”
The health district conducted an investigation into the cases and learned they “had a common exposure outside of work,” Bethel said. “The staff members contacted during the investigation isolated themselves as part of COVID-19 protocols. In addition, there have been no reported secondary cases and the investigation has been closed.”
If mishandling of vaccine isn’t to blame, what might account for eight cases in fully vaccinated people from a single exposure?
One factor could be that the delta variant, currently the most common strain of the virus in Nevada, spreads more easily than other strains and is thought to be better able to break through immunity created by vaccination or prior infection. There also are potentially even more contagious mutations of the delta variant emerging.
“The viruses that are circulating in July aren’t the viruses that were circulating in February. These are the Olympians now,” said Mark Pandori, director of the Nevada State Public Health Laboratory. “The ones that are circulating now have a better ability to get around vaccination.”
The virus is also more likely to spread from an individual with a “high viral load,” or a high level of virus in their body. An individual with a high viral load coming into close contact with a lot of people at a gathering might result in new infections in multiple vaccinated people, he said.
“Maybe there was something about this particular party that made transmission a far greater affair,” said Pandori, who had no direct knowledge of the cluster. “Were they participating in some kind of activity or behavior that would have fostered transmission?”
“If, as an example, everybody’s doing Jell-O shots from the same vessel or something,” he said, speaking hypothetically. “Well, now you’ve created in an environment where there’s going to be a particular challenge in terms of immunity.”
As of Thursday, the health district had reported 92 hospitalizations in Clark County of people with COVID-19 who had been fully vaccinated: 12 in 25- to 49-year-olds; 15 among those 50 to 64; and 65 among those 65 and older.
Eight of the hospitalized patients died. Due to the small number, their ages were withheld to “protect privacy and confidentiality.”
Not all cases counted
Due to a change in how breakthrough cases are reported, the data on them is incomplete.
Beginning May 1, the Centers for Disease Control and Prevention stopped monitoring all reported vaccine breakthough cases, focusing instead on those resulting in hospitalization or death. The state of Nevada and the health district, in turn, stopped reporting totals of identified cases.
However, in a June 22 email, a health district official told other agency officials there had been 471 identified breakthrough cases in Clark County, with 53 resulting in hospitalization and eight in death. In other words, there were nearly 10 times as many breakthrough cases identified as were publicly disclosed.
The health district did not grant a request for an interview on breakthrough cases, but noted in a statement that such cases are unsurprising.
“It is important to remember that no vaccines are 100 percent effective and breakthrough cases are expected,” Bethel said. “To date more than 2 million doses of COVID-19 vaccine have been administered in Clark County. The three vaccines currently available provide protection against serious illness in breakthrough cases.”
In laboratory tests, the Pfizer and Moderna vaccines were about 95 percent effective in preventing symptomatic cases of COVID-19. That means that about 1 in 20 people could become sick after being vaccinated, though their infections would be less likely to be severe. The Johnson &Johnson vaccine was shown to be about 66 percent effective in preventing infection in trials around the globe and 74 percent effective in the U.S.
Unvaccinated drive spike
Brian Labus, an epidemiologist and assistant professor with the UNLV School of Public Health, said cases in unvaccinated people — not breakthrough cases — are driving the state’s current spike in new COVID-19 infections.
The hundreds of known breakthrough cases in Clark County do not compare in volume to the hundreds of new cases that are being reported daily in unvaccinated people, he said.
He acknowledged that people may be surprised to hear of breakthrough cases if they don’t understand that the protection offered by vaccine, though considerable, is imperfect.
“I would say it’s like wearing a seat belt in a car,” Labus said. “Just because there’s the occasional death of somebody who is … wearing the seat belt when the car crash occurs doesn’t mean you shouldn’t wear a seat belt.
“It’s going to protect most people for the most part.”