Fully Vaccinated People Account for 1 in 4 COVID Cases Here, New CDC Report Says

A substantial portion of the COVID cases in this metropolitan area are breakthrough cases.

If you got the COVID vaccine, you may have expected to evade the virus completely. However, as public health officials and experts from the Centers for Disease Control and Prevention (CDC) have repeatedly reminded us, no vaccine is 100 percent effective, which leaves room for breakthrough cases. Especially as the more contagious Delta variant has become the most prominent strain circulating in the U.S., it seems we're hearing more and more about COVID cases among the vaccinated. And currently, in one major metropolitan area, one in four newly reported COVID cases are among people who are fully vaccinated, according to a new study from the CDC.

RELATED: 85 Percent of Breakthrough COVID Cases Now Have This in Common, Study Says.

The study, published in the CDC's Morbidity and Mortality Weekly Report on Aug. 27, examined more than 43,000 COVID infections that were reported in California's Los Angeles County between May 1 and July 25. The findings showed that the overwhelming majority of infected people, 71 percent, were unvaccinated. Three percent were partially vaccinated at the time they were infected and 25 percent were fully vaccinated.

While breakthrough infections are to be expected, they're often much less severe than COVID cases among unvaccinated people. The CDC study found that unvaccinated people infected with COVID were 29 times more likely to require hospitalization than those who were fully vaccinated. The study noted that "efforts to increase COVID-19 vaccination, in coordination with other prevention strategies, are critical to preventing COVID-19–related hospitalizations and deaths."

Virologist Angela Rasmussen, PhD, told NBC News that the new research seems to be "consistent with a lot of the data coming in: Delta causes more breakthroughs, including symptomatic breakthrough, but vaccination dramatically reduces critical illness and death." She pointed out that "the vaccines are holding up where it matters most—keeping people out of the ICU and out of the morgue."

One of the study's authors, Sharon Balter, MD, told NBC News that the study's findings indicate "that vaccinated persons are much less likely to have severe illness and may only have mild symptoms." However, she added that since vaccinated people can still get COVID, "vaccinated people [should] wear masks to prevent spread to unvaccinated people who may become severely ill."

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The COVID vaccines are intended to prevent severe illness from the virus, a point the CDC recently clarified on its page about breakthrough cases. "COVID-19 vaccines protect people against severe illness, including disease caused by Delta and other variants circulating in the U.S.," they point out. The agency notes that fully vaccinated people are often asymptomatic, but even when they do develop symptoms, they're much less likely to result in hospitalization or death.

As the new CDC study highlights, breakthrough cases still remain significantly less common than COVID cases among the unvaccinated. In early August, NBC News reported that data from the Kaiser Family Foundation showed that 1 in 900 people get COVID after being fully vaccinated.

In light of the CDC study, Barbara Ferrer, the Director of Public Health in L.A. County, said in a statement, "Data continues to provide reassurance that fully vaccinated people are protected from severe COVID-19 illness." She added, "We must continue to increase COVID-19 vaccinations, in coordination with other prevention strategies like masking, testing, contact tracing, and quarantine; these efforts are critical to preventing COVID-19 hospitalizations and deaths."

RELATED: 74 Percent of Vaccinated People Who Get Severe COVID Have This in Common.

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