CDC Finds Very Small Number of Coronavirus Infections in Vaccinated People

The Centers for Disease Control and Prevention documented over 10,200 cases of coronavirus infections in fully vaccinated people as of late April.

Over 101 million people were fully vaccinated by that date, meaning far less than 1% of vaccinated people were reportedly infected with the virus, according to CDC's report, which was published on Tuesday.

Experts warned that the "breakthrough" infections would happen because no vaccine is perfect.

"Even though FDA-authorized vaccines are highly effective, breakthrough cases are expected, especially before population immunity reaches sufficient levels to further decrease transmission," the report said. "However, vaccine breakthrough infections occur in only a small fraction of all vaccinated persons and account for a small percentage of all COVID-19 cases."

Of the 10,262 breakthrough infections documented, more than 60% were in women, but the agency noted that "the age and sex distribution of reported vaccine breakthrough infections reflects the fully vaccinated U.S. population."

Preliminary data on the cases show that 27% were asymptomatic, meaning that most infected people did show symptoms of the virus.

Ten percent of the infected individuals required hospitalization and 160 of them died. The median age of the deceased patients was 82 years old. Among the nearly 1,000 people who required hospitalization, nearly 30% were asymptomatic or hospitalized for a reason unrelated to the coronavirus, according to the report.

Just 5% of cases had sequence data available that showed that the majority of those infections were caused by variants of concern. The World Health Organization last week said that currently available coronavirus vaccines appear to be effective against variants, and the CDC said that the "proportion of reported vaccine breakthrough infections attributed to variants of concern has also been similar to the proportion of these variants circulating throughout the United States."

The report acknowledged that the documented breakthrough cases are likely a "substantial" undercount because reporting is voluntary and many fully vaccinated individuals might skip testing.