The claim: Merriam-Webster removed the immunity part of its 'vaccine' definition
Merriam-Webster, the company known for its reference books and dictionaries, has become the source of online misinformation about vaccines.
"Vaccine used to be defined as a substances that provides 'immunity' to a specific disease," reads the text of an Instagram post shared Nov. 4. "Now, Merriam Webster has literally changed the definition of 'vaccine' and removed the 'immunity' portion in order to possibly cover for the fact that the COVID 'vaccines' don't actually provide immunity from COVID."
The post generated close to 27,000 likes in less than a week. Other social media users have shared false claims that Merriam-Webster changed the definition of "anti-vaxxer," PolitiFact reported.
This claim is missing context, too.
Merriam-Webster revised its "vaccine" definition to replace "immunity" with "immune response." The change also addresses the new technology of mRNA vaccines in light of the COVID-19 pandemic.
The company told USA TODAY the goal was to be scientifically accurate about how vaccines work, not to question their effectiveness.
USA TODAY reached out to the social media user who shared the post for comment.
Definition changed 'immunity' to 'immune response'
Peter Sokolowski, editor at large for Merriam-Webster, told USA TODAY in an email that the company changed its "vaccine" definition to include more scientifically accurate language.
"Merriam-Webster adds definitions and evolves existing ones to accurately report on how words are used," he said.
According to an archived version of the dictionary's website, Merriam-Webster formerly said a "vaccine" was "a preparation of killed microorganisms, living attenuated organisms, or living fully virulent organisms that is administered to produce or artificially increase immunity to a particular disease."
The new definition of "vaccine", published in May, reads: "a preparation that is administered – as by injection – to stimulate the body's immune response against a specific infectious agent or disease."
The editors changed "artificially increase immunity" to "stimulate the body’s immune response" because they believed it would be more helpful to readers, according to Sokolowski.
"The definition (of) immune response provides a detailed description of how a vaccine actually works and is therefore more specific, scientific and complete than the more general term immunity," Sokolowski said.
Definition addresses mRNA vaccines
The new definition also reflects the newer medical technology of messenger RNA (mRNA) vaccines, according to Sokolowski.
mRNA vaccines have been studied for years, but have recently become available to the public, according to the Centers for Disease Control and Prevention.
mRNA is a section of deoxyribonucleic acid (DNA) that leaves the nucleus of a cell to help make encoded protein. Once the mRNA has performed its task, it is destroyed.
The Pfizer-BioNTech and Moderna's mRNA vaccines, used to help provide protection against the virus that causes COVID-19, are the only two mRNA vaccines authorized in the U.S. According to the CDC, the vaccines work by teaching cells "how to make protein that will trigger an immune response inside our bodies."
The response produces antibodies that help fight off COVID-19, according to the CDC.
The new vaccine definition in Merriam-Webster's dictionary has two sub-definitions that elaborate on the function of a vaccine, a feature that was not present in the old definition.
The first sub-definition addresses an "antigenic preparation of a typically inactivated or attenuated pathogenic agent (such as a bacterium or virus) or one of its components or products (such as a protein or toxin)."
The second sub-definition addresses the mRNA vaccine with the definition "a preparation of genetic material (such as a strand of synthesized messenger RNA) that is used by the cells of the body to produce an antigenic substance (such as a fragment of virus spike protein)."
COVID-19 vaccines build immunity to virus
Merriam-Webster's change is in line with updates the Centers for Disease Control and Prevention made to its vaccine definition.
In September, the CDC changed its vaccine definition from “a product that stimulates a person’s immune system to produce immunity to a specific disease” to "a preparation that is used to stimulate the body’s immune response against diseases," according to the Miami Herald.
Belsie Gonzalez, senior public affairs specialist for the CDC, told USA TODAY the agency made the change independently of Merriam-Webster's decision.
"The previous definition could be interpreted to mean that vaccines were 100% effective, which has never been the case for any vaccine, so the current definition is more transparent and also describes the ways in which vaccines can be administered," Gonzalez said via email.
Vaccines "imitat[e] an infection," according to the CDC, which causes the immune system to produce antibodies that help fight an illness. Mild side effects from vaccination are normal and a sign the body is developing immunity.
It takes two weeks after someone is fully vaccinated against COVID-19 to develop immunity against the virus, according to the CDC.
"It is possible that a person could be infected with the virus that causes COVID-19 just before or just after vaccination and then get sick because the vaccine did not have enough time to provide protection," the agency says on its website.
Our rating: Missing context
Based on our research, we rate MISSING CONTEXT the claim that Merriam-Webster removed the immunity part of its vaccine definition, because without additional information the claim is misleading. Merriam-Webster revised its definition of vaccine to replace "immunity" with "immune response." The change also addresses the new technology of mRNA vaccines made publicly available in response to the COVID-19 pandemic. The company said the goal was to be scientifically accurate about how vaccines work, not to cast doubt on their effectiveness.
Our fact-check sources:
Merriam-Webster, accessed Nov. 9, Definition of 'vaccine'
Miami Herald, Sept. 27, Why did CDC change its definition for ‘vaccine’? Agency explains move as skeptics lurk
Peter Sokolowski, Nov. 10, Email exchange with USA TODAY
Belsie Gonzalez, Nov. 10, Email exchange with USA TODAY
Merriam-Webster, accessed Nov. 10, Definition of 'immune response'
Merriam-Webster via Wayback Machine, accessed Nov. 10, Archive of 'vaccine' definition
Centers for Disease Control and Prevention, Sept. 1, Immunization: The basics
Centers for Disease Control and Prevention, May 21, Understanding How COVID-19 Vaccines Work
USA TODAY, Aug. 5, Fact check: 6 of the most persistent misconceptions about COVID-19 vaccines
Centers for Disease Control and Prevention, Aug. 17, 2018, Understanding how vaccines work
PolitiFact, May 17, No, Merriam-Webster didn’t change the definition of ‘anti-vaxxer’
Centers for Disease Control and Prevention, Nov. 12, Myths and Facts about COVID-19 Vaccines
Centers for Disease Control and Prevention, Nov. 3, Understanding mRNA COVID-19 Vaccines
Contributing: Miriam Fauzia
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This article originally appeared on USA TODAY: Fact check: Merriam-Webster changed 'vaccine' definition for accuracy