the individual required hospital care, and that case occurred in an unvaccinated worker, the researchers say. No one died.
And although 94 of the 125 cases reported in July occurred in vaccinated workers, the key number to look at is what the researchers call the “attack rate.”
According to the study, in July there were about 5.7 cases of COVID-19 per every 1,000 vaccinated workers at UCSD Health.
Compare that to the attack rate among the unvaccinated: 16.4 cases of COVID-19 per every 1,000 workers.
READ: Experts Explain Why Fully Vaccinated People are Still Getting Infected With COVID-19
That means that an unvaccinated person was nearly three times more likely to contract COVID-19 compared to a fully vaccinated person.
As for symptoms, in a tally of cases occurring among UCSD health workers from March through July, “symptoms were present in 109 of the 130 fully vaccinated workers [83.8%] and in 80 of the 90 unvaccinated workers [88.9%],” the study found.
The new study represents a detailed look at COVID infection rates, because UCSD Health “has a low threshold for SARS-CoV-2 testing, which is triggered by the presence of at least one symptom during daily screening or by an identified exposure, regardless of vaccination status,” the authors note.
Dr. Amesh Adalja is an expert in infectious disease and a senior scholar at the Johns Hopkins Center for Health Security in Baltimore. Reading over the findings, he says that they support the effectiveness and necessity of getting vaccinated against the new coronavirus.
“Vaccines aren’t force fields — breakthrough infections will occur, especially as people get back to their activities in the midst of the more contagious Delta variant,” Adalja says.
“The breakthroughs were all mild, with no one hospitalized,” he adds. “To me, that shows the vaccines are doing what they were designed to: taming the virus.”
To learn more about breakthrough infections and vaccinations, visit the CDC.