According to data released Tuesday by the Centers for Disease Control and Prevention, more than 10,000 people in the United States have become infected with COVID-19 since being immunised against the virus.
As of April 30, about 101 million people in the United States have administered all doses of the two-shot Pfizer-BioNTech or Moderna vaccinations, or the single-shot Johnson & Johnson vaccine, according to the CDC.
According to the data, 27 percent of the more than 10,000 individuals diagnosed with so-called “breakthrough infections” – or infections that emerge following complete vaccination – have no signs of the virus.
However, 10% of these patients were hospitalized following infection and 2% ultimately died.
“Even though FDA-authorized vaccines are highly effective, breakthrough cases are expected, especially before population immunity reaches sufficient levels to further decrease transmission,” the agency researchers wrote.
“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,” they said.
According to study, the Pfizer-BioNTech and Moderna vaccines provide more than 90% protection against severe illness caused by the coronavirus, while the Johnson & Johnson shot is more than 70% safe.
The vaccines’ safety is expected to last at least six months.
Vaccines, however, do not always prevent infection. According to the CDC, they instead boost the immune system so that sick individuals do not experience serious symptoms.
According to the department, an individual is deemed completely vaccinated 14 days after getting the second dose of either of the two-dose drugs or 14 days after receiving the single-dose injection.
Sixty-three percent of the breakthrough infections in fully vaccinated people occurred in women, and most of those diagnosed were older adults age 40 to 74.
Nearly 60% of the breakthrough infection cases involved the B.1.1.7, or “U.K.” variant of the virus, while one in four were the B.1.429, or California, strain.
These strains are believed to be more contagious than the one first identified in Wuhan, China, in late 2019, according to the CDC.
Only 5% of the samples collected from the more than 10,000 breakthrough cases, however, underwent analysis for genetic variants.
“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 agency researchers wrote.
Still, “the number of COVID-19 cases, hospitalizations, and deaths that will be prevented among vaccinated persons will far exceed the number of vaccine breakthrough cases,” they said.