Does a study by University of Colorado medical researchers show that the "vast majority of humanity has gotten the COVID-19 vaccine via "shedding," meaning the vaccine spread from person to person? No, that's not true: The study's lead author told Lead Stories that the social media post making this assertion "does not properly reflect the findings of our study."
Also, there's no credible scientific evidence supporting the claim. Vaccines work by stimulating the immune system to produce an immune response without causing the disease itself. They do not shed or spread from person to person in the way that viruses do.
The claim appeared in a post on X (archived here), the social-media platform formerly known as Twitter, on July 29, 2023. It was published on the Leading Report account. The post said:
BREAKING: A study conducted by scientists at the University of Colorado confirms the vast majority of humanity has gotten the COVID vaccine via 'shedding,' whether they wanted it or not.
This is what the post looked like on X at the time of the writing of this fact check:
(Source: X screenshot taken on Fri Aug 4 15:20:37 2023 UTC)
The study
The string of tweets shares a link to a preprint version of the study, which was later published, following peer review, in the journal ImmunoHorizons on May 9, 2023, under the title "Evidence for Aerosol Transfer of SARS-CoV-2-Specific Humoral Immunity."
In an August 4, 2023, email to Lead Stories, the study's lead author, Ross Kedl, a professor of immunology and microbiology at the University of Colorado Anschutz School of Medicine, said, "This social media post is far from accurate." He continued:
I cannot believe that this has been manipulated this badly by those that have such a screwed-up agenda. The levels of incompetence one has to have in order to use my paper as evidence for antigen shedding is almost impossible to quantify.
The vaccine-shedding concept promoted in the social media post circulates often enough that the Centers for Disease Control and Prevention (CDC) has included it among its list of "Myths and Facts about COVID-19 Vaccines." The page on the CDC website reads:
MYTH: COVID-19 vaccines authorized for use in the United States shed or release their components.
FACT: Vaccine shedding is the release or discharge of any of the vaccine components in or outside of the body and can only occur when a vaccine contains a live weakened version of the virus.
None of the vaccines authorized for use in the U.S. contain a live virus. mRNA and viral vector vaccines are the two types of currently authorized COVID-19 vaccines available.
Saying the tweet on X "does not properly reflect the findings of our study," Kedl continued his response:
Nothing about our study has any relationship to 'antigen shedding' whatsoever. We found that all of us have ANTIBODIES in our saliva and nasal cavity such [that] these ANTIBODIES get breathed out during normal respiration. This can be detected by essentially 'washing off' the inside of someone's mask that they wore for the day and finding that ANTIBODIES were stuck there. This is not antigen from the vaccine, this has nothing to do with the vaccine itself, there is no 'shedding' going on.
Additional reading
Lead Stories previously debunked claims that COVID vaccines threaten unvaccinated people through someone who's already received a vaccine.
Additional Lead Stories fact checks of claims related to vaccines can be found here.
