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Please note!
This fact brief was originally published as an experiment to test the concepts behind fact briefs.
Readers should be aware that while there is still a lot of useful information in fact briefs like this one, not all of them reflect Gigafact's current methods and standards for fact briefs. If you come across any that you feel are out of date, don't hesitate to contact us at support@gigafact.org.
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FACT BRIEF

Is the delta coronavirus variant challenging some of the protective effects of COVID-19 vaccines?

By Austin Tannenbaum
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YES

Vaccines appear to be less effective at slowing the spread of the coronavirus’s delta variant, contributing to increased caseloads and a greater risk of contracting symptomatic COVID-19, even among the vaccinated. 

The American Society of Microbiology estimates that the delta variant is “40%-60% more transmissible than the alpha [variant] and almost twice as transmissible as the original...strain." The ASM outlined related challenges posed by delta, including:

  • Higher viral loads, causing greater contagiousness.
  • Antibodies that are less able to neutralize the virus.
  • Slightly less protection against symptomatic “breakthrough” disease for the vaccinated.

Delta is currently responsible for 83% of U.S. coronavirus infections. Infections that cause severe symptoms increase the chance of mutations into other variants, leading public health leaders and scientists to urge continued efforts to increase vaccination rates.

Vaccinated people continue to be well-protected against serious disease and death.

This fact brief is responsive to conversations such as this one.
Sources
American Society for Microbiology How dangerous is the delta variant (B.1.617.2)?
Nature How do vaccinated people spread delta? What the science says
ABOUT THE CONTRIBUTOR
Gigafact
Between 2020 and 2022, under close editorial supervision, Gigafact contracted a group of freelance writers and editors to test the concepts for fact briefs and provide inputs to our software development process. We call this effort Gigafact Foundry. Over the course of these two years, Gigafact Foundry writers published over 1500 fact briefs in response to claims they found online. Their important work forms the basis of Gigafact formats and editorial guidelines, and is available to the public on Gigafact.org. Readers should be aware that while there is still a lot of relevant information to be found, not all fact briefs produced by Gigafact Foundry reflect Gigafact's current methods and standards for fact briefs. If you come across any that you feel are out of date and need to be looked at with fresh eyes, don't hesitate to contact us at support@gigafact.org.
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About fact briefs published on Gigafact
Fact briefs are short, credibly sourced summaries that offer “yes/no” answers in response to claims found online. They rely on publicly available, often primary source data and documents. Fact briefs are created by contributors to Gigafact —a nonprofit project looking to expand participation in fact-checking and protect the democratic process. See all fact briefs here.