The CDC’s Revised Definition of Vaccination Is for Clarity

14th September 2021

The CDC’s Revised Definition of Vaccination Is for Clarity

Government sites often update definitions as changes arise (Getty Images).

The Claim

The CDC is downplaying the ineffectiveness of coronavirus vaccines by changing the definition of vaccination on its site.

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Emerging story

A recent Twitter thread from U.S. Representative Thomas Massie highlighted that the CDC’s definition of vaccination has changed a number of times over the last decade. The first tweet included a comparison between the CDC to the totalitarian Ministry of Truth in George Orwell’s novel 1984. The next tweets gave links to the changing definitions on the Internet Archive Wayback Machine and retweeted another tweet, which has since been suspended.

These tweets have gained significant attention on Twitter, with the initial tweet in the thread gaining over 22,0000 likes within days. The other tweets have gained hundreds of interactions. Others have managed to gain hundreds of interactions by retweeting Representative Massie’s claims.

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Misbar’s Analysis

A CDC spokesperson has stated that the revised wording is an attempt to make the overall information more transparent for readers. They also stated that the changed wording has not affected the overall definition of vaccination on the CDC website. The spokesperson denied that the changes meant that the coronavirus vaccine is less effective than other vaccines and that it has never been the case that any vaccine is completely effective.

Representative Massie specifically highlights three words to make his claim that the CDC is changing the overall definition of vaccination. He states that prior to 2015, the CDC said that vaccines would “prevent” disease. From 2015 to 2021, the CDC said that vaccines would produce “immunity” to disease. And in September 2021, the word immunity was changed to “protection.” On other websites, all of these terms are used to describe vaccines and are sometimes used interchangeably. For example, the National Institute of Health’s MedlinePlus website states that immunization can mean the same thing as vaccination. And the sentence that explains this has an additional clause which states that this definition means getting “protected” from a disease.

Dictionary.com also highlights how vaccination and immunization can often be used in overlapping ways. It also states that both vaccination and immunization have the goal of “preventing” people from diseases. This reinforces the CDC spokesperson’s statement that the overall definition of vaccination has not changed. Instead, it appears to be an effort in clarifying the existing meaning using suitable terminology.

Significant evidence suggests that coronavirus vaccines are effective in preventing illness. In fact, they are more effective than other comparable vaccines. In the 2019-2020 flu season, the flu vaccine was 39% effective. The MMR vaccine is 88% effective against mumps after two shots. Comparatively, the Pfizer and Moderna vaccines were initially 95% effective at preventing coronavirus. And even with the delta variant, studies show that the vaccines are still above 80% effective against symptomatic illness.

Additionally, government websites often update their site’s definitions. For example, at the time of writing, the National Institute of Standards and Technology last updated the glossary terms and definitions of the Computer Security Resource Center on September 7th, 2021. The Internet Archive Wayback Machine shows that before this, the site had previously updated its definitions on August 5th, 2021.