More than 10,000 vaccine breakthrough infections have been reported in the U.S. in individuals who had already been fully vaccinated against COVID-19, according to the U.S. Centers for Disease Control and Prevention.
"A total of 10,262 SARS-CoV-2 vaccine breakthrough infections had been reported from 46 U.S. states and territories as of April 30, 2021," the government agency said. The report covered the period from January 1 to April 30 this year.
More than half (63%) of the breakthrough cases happened in females, according to the CDC. Preliminary data indicated that more than a quarter (27%) of the cases were asymptomatic and 160 people (2%) passed away. But 28 of the deceased were asymptomatic or passed away due to a cause not connected to coronavirus. The median age for the deceased was 82.
The CDC noted that the quantity of reported vaccine breakthrough cases probably falls far short of the actual amount of breakthroughs among the vaccinated.
"The findings in this report are subject to at least two limitations. First, the number of reported COVID-19 vaccine breakthrough cases is likely a substantial undercount of all SARS-CoV-2 infections among fully vaccinated persons. The national surveillance system relies on passive and voluntary reporting, and data might not be complete or representative. Many persons with vaccine breakthrough infections, especially those who are asymptomatic or who experience mild illness, might not seek testing. Second, SARS-CoV-2 sequence data are available for only a small proportion of the reported cases," the agency noted.