The Centers for Disease Control and Prevention (CDC) altered the definition of “vaccine” because of concern that the definition didn’t apply to COVID-19 vaccines, according to newly released internal emails.
The agency updated its definition on Sept. 1.
The definition was formerly, “A product that stimulates a person’s immune system to produce immunity to a specific disease, protecting the person from that disease.” That definition now reads, “A preparation that is used to stimulate the body’s immune response against diseases.”
One CDC employee in August, shortly before the definition was changed, said the definition was being used by “right-wing COVID-19 pandemic deniers … to argue that mRNA vaccines are not vaccines,” according to the newly published emails.
The Pfizer and Moderna COVID-19 vaccines utilize messenger RNA technology. All three COVID-19 vaccines authorized for use in the United States plummet in effectiveness against infection several months after receiving them, after initially being promoted as protecting against infection and severe disease.
The definition “was twisted to claim that the existing COVID-19 vaccines were not vaccines because they only prevented severe illness,” the CDC employee said.
Alycia Downs, lead health communication specialist for the agency, messaged a colleague on Aug. 19, saying that she needed to update the definition and others like it, “since these definitions are outdated and being used by some to say COVID-19 vaccines are not vaccines per CDC’s own definition.”
Downs didn’t get a response, so she messaged again the following week.
“The definition of vaccine we have posted is problematic and people are using it to claim the COVID-19 vaccine is not a vaccine based on our own definition,” she wrote.
Valerie Morelli, another CDC official, approved the change on Sept. 1, even though it seems to differ greatly from a definition she had laid out in an earlier document (pdf).
“If this is for the general public, I am good with the change,” Morelli wrote.
The emails were obtained by attorney Travis Miller through a Freedom of Information Act request. The CDC didn’t dispute their authenticity.
