NBC News reported that by examining over 40,000 COVID-19 cases reported in Los Angeles County between May 1 and July 25, researchers found that by the time the Delta variant had become dominant on July 25.
Speaking to NBC News, Dr. Sharon Balter, one of the study's authors and an infectious disease director at the Los Angeles County Department of Public Health said, "This means that vaccinated persons are much less like to have severe illness and may only have mild symptoms."
"This is a great reason to get vaccinated," he added.
"At the same time, because vaccinated people can get Covid and may have mild symptoms, we do encourage vaccinated people to wear masks to prevent spread to unvaccinated people who may become severely ill," Balter further added.
"These infection and hospitalization rate data indicate that authorized vaccines were protective against SARS-CoV-2 infection and severe COVID-19 during a period when transmission of the Delta variant was increasing," the report said.
Meanwhile, Angela Rasmussen, a virologist with the Vaccine and Infectious Disease Organization at the University of Saskatchewan in Canada, said the findings were "consistent with a lot of the data coming in: delta causes more breakthroughs, including symptomatic breakthrough, but vaccination dramatically reduces critical illness and death."
"The vaccines are holding up where it matters most — keeping people out of the ICU and out of the morgue," Rasmussen said.
According to public health data, nearly a month after the data period ended, as many as 64 percent of Los Angeles County residents ages 12 and up are currently fully vaccinated.