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

Tuesday, August 17, 2021
By Austin Tannenbaum

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.
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 If you come across any that you feel are out of date and need to be looked at with fresh eyes, don't hesitate to contact us at support@gigafact.org.