Leaked Video Clip of Zuckerberg Discussing Vaccines Omits Context

In July 2020, Facebook CEO Mark Zuckerberg held one of the company's regular internal Q&As for company employees. We obtained a transcript.

Published Feb. 6, 2023

Mark Zuckerberg testifies in an unrelated video conference on July 29, 2020, in Washington, D.C. (Photo by Graeme Jennings - Pool/Getty Images) (Graeme Jennings - Pool/Getty Images)
Mark Zuckerberg testifies in an unrelated video conference on July 29, 2020, in Washington, D.C. (Photo by Graeme Jennings - Pool/Getty Images)

On Jan. 20, 2023, Twitter user James Cintolo (@healthbyjames) posted a leaked video that purportedly showed Meta/Facebook CEO Mark Zuckerberg talking about COVID-19 vaccines in August 2021.

In the video, Zuckerberg could be heard saying, "I share some caution on this, because we just don't know the long-term side effects of basically modifying people's DNA and RNA to directly encode in a person's DNA and RNA basically the ability to produce those antibodies, and whether that causes other mutations or other risks downstream."

The tweet's caption read, "BREAKING — Leaked Video Of Mark Zuckerberg Warning His Staff Not To Take A COVID Vaccine."

Despite the date imprinted on the video, it was not from August 2021. The clip came from an internal Q&A for Facebook employees that took place in July 2020, back in the early days of the pandemic. At the time, COVID-19 vaccines were still months away from becoming available to the public.

More importantly, this brief video clip lacked context, and, at the time these remarks were made, Zuckerberg lacked a proper understanding of how mRNA vaccines (the type then being developed by Moderna and Pfizer) work.

Lastly, at no point is Zuckerberg heard "warning his staff not to take a COVID vaccine."

Original Video

The leaked video was first published by Project Veritas on Feb. 16, 2021, and included one additional sentence that wasn't part of the January 2023 Twitter upload. Zuckerberg had said, "So, there's work on both paths of vaccine development."

The brief video was originally made available on the Project Veritas website, while a shorter version was posted by the company's founder, James O'Keefe, apparently to fit into a Twitter video time limit of two minutes and twenty seconds.

"We would know none of this, but not for the fact that we have a brave Facebook insider that continues to leak and transmit videotape of Facebook executives to Project Veritas," O'Keefe said in the video. "It's not that the insider is betraying Mark Zuckerberg. It's that Mark Zuckerberg is betraying what Facebook ought to stand for."

Zuckerberg's Full Answer

Two years later, in February 2023, Snopes obtained a transcript of Zuckerberg's full answer, which showed that some context was missing from the original video.

In Zuckerberg's full remarks on vaccine progress, which were not shared by Project Veritas, he referenced positive news about Moderna's vaccine trial, a development that covered on July 15, 2020:

There are some good – there was a positive announcement by Moderna about their – you know, their first round of trials this week. It was a safety trial for 45 people. No one has any bad side effects yet. But I have to say, there are a couple of different paths to a vaccine here. There's sort of the traditional path, where you modify a virus to make it a little less – to make it harmless, or at least less harmful, and then inject it in, and then have the body develop antibodies to fight it. There's a new approach that people are trying, which is called an RNA vaccine, which is what this Moderna vaccine is basically attempting to do, which is just basically injecting RNA directly into a person to turn a person's own cells directly into a factory for producing antibodies by basically appending the genetic code to create antibodies into your own genome rather than just kind of exposing your body to the virus and have it fight and develop an immune response on its own, and... I think that if this is possible and safe, then I think it would be a huge breakthrough, and it would be a great path going forward for more rapidly developing, basically, vaccines for a whole lot of other viruses that come in the future ...

Then came the brief moment that appeared in the Project Veritas video, which has been bolded below:

... but I do just want to make sure that I share some caution on this, because we just don't know the long-term side effects of basically modifying people's DNA and RNA to directly encode in a person's DNA and RNA, basically, the ability to produce those antibodies, and whether that causes other mutations or other risks downstream. So there's work on both paths of vaccine development. Certainly, the initial Moderna results are good. But I also wouldn't get over-hyped by that. I think we're still unlikely to have a vaccine sometime before the middle of next year. But certainly, I don't think we've gotten any particularly bad news yet that would suggest that it has to take longer than we thought in the past.

However, Zuckerberg was incorrect about his "caution" regarding vaccines "modifying people's DNA and RNA," a point on which he soon apparently found clarity, as we'll explain in the next section.

Zuckerberg and Fauci

On Nov. 30, 2020, weeks before COVID-19 vaccines began to become available to some members of the general public, Zuckerberg spoke for one hour in a publicly broadcast live video session with Dr. Anthony Fauci. Fauci, who has since retired, was regarded as the nation's top infectious disease expert. Project Veritas included a portion of this discussion in its article and video.

During the remarks, Zuckerberg asked Fauci for clarification regarding the claim that vaccines "alter" DNA and RNA, beginning at the 31:44 mark in this video.

Here's a transcript of the relevant portion of the discussion:

Zuckerberg: So I've heard from a lot of people who have questions about a new type of vaccine that involves RNA or DNA and why we can expect that this can be safe without having any issues down the line. So I'm curious to hear, you know, how you would explain that scientifically and your thoughts on that concern overall.

Fauci: Yeah, because we know what happens from a lot of work in the animal models, so that RNA that pumps it out pumps it out for a very limited period of time, enough to get a good immune response and then the RNA degrades the way RNA generally degrades under most circumstances, so what the FDA has done is that they are not going to consider an EUA until 60 days following the time that half the people in the trial have received their last dose, and the reason the 60 days is the magic number, because when you look at the experience over decades with vaccines, the intermediate and long-term adverse events almost all occur between 30 and 45 days. So if you wait 60 days, you cushion it a little and overshoot a little and if you don't see severe events during that time, it's extremely unlikely that you're going to see severe adverse events.

Zuckerberg: And just to clear up one point. My understanding is that these vaccines do not modify your DNA or RNA. So I think that's just an important make to clarify. If I'm getting anything wrong here, of course correct me, but just to make that clear.

Fauci: No. First of all, DNA is inherent in your own nucleus cell. Sticking in anything foreign will ultimately get cleared. Messenger RNA is the messenger. It comes from the DNA to the RNA to the protein. Sticking in mRNA into you has absolutely nothing to do with your own DNA or your own RNA. It's going to perform its function and then it's going to be degraded and it's gone. It doesn't have any imprint on any genetic material of your own.

Mark Zuckerberg: Good, well I'm glad we could clear that up.

Since the time that this discussion took place in November 2020, Meta launched what it called "the largest worldwide campaign to promote authoritative information about COVID-19 vaccines." Zuckerberg at least twice posted about being vaccinated himself, and also was interviewed by "CBS This Morning" host Gayle King where he talked about vaccine mandates for Meta employees.

Additionally, a search of Zuckerberg's Facebook feed also revealed that, in December 2022, the Chan Zuckerberg Biohub posted that they, along with Stanford University had "developed a promising new COVID vaccine that, in experiments, [showed] a robust protection against all variants of concern."

Debunking the DNA and RNA Claim

Here is a sampling of organizations, publications, and institutions that have disproved the claim that mRNA COVID-19 vaccines alter a person's DNA or RNA: U.S. Centers for Disease Control and Prevention (CDC), World Health Organization (WHO)Mayo Clinic, Britannica, the Australian government's Department of Health and Aged Care, Children's Hospital of Philadelphia, Nebraska Medicine, First Nations Health Authority, the National Human Genome Research InstituteCincinnati Children's Hospital Medical Center, and Harvard T.H. Chan School of Public Health at Harvard University, just to name a few.

The Associated Press interviewed Dr. Daniel Kuritzkes, chief of infectious diseases at Brigham and Women's Hospital, who explained why the rumor is a "complete fallacy."

The Washington Post spoke with Jason L. Schwartz, an assistant professor of health policy at the Yale School of Public Health, who said, "There literally is no physical connection between the RNA in these vaccines and the DNA in our cellular nuclei, so there's no possibility for that connection, let alone for effects or adaptations."

We found similar reporting from Reuters and The New York Times that also put this false rumor to bed.


Assis, Claudia. "Moderna Stock Surges 17% on Coronavirus Vaccine Trial News." MarketWatch, 15 July 2020,

Chiu, Allyson, and Lindsey Bever. "Are They Experimental? Can They Alter DNA? Experts Tackle Lingering Coronavirus Vaccine Fears." Washington Post, 14 May 2021,

"Facebook CEO Mark Zuckerberg Takes 'Anti-Vax' Stance in Violation of His Own Platform's New Policy … 'I Share Some Caution on This [Vaccine] Because We Just Don't Know the Long-Term Side Effects of Basically Modifying People's DNA and RNA.'" Project Veritas, 16 Feb. 2021,

"Fact Check-MRNA Vaccines Do Not Turn Humans into 'Hybrids' or Alter Recipients' DNA." Reuters, 13 Apr. 2021,

Fichera, Angelo. "No, COVID Shots Don't Change Human DNA to a 'Triple Helix.'" The Associated Press, 5 Oct. 2022,

HealthGuard. "The Top COVID-19 Vaccine Myths Spreading Online." Britannica,

Mayo Clinic Staff. "Different Types of COVID-19 Vaccines: How They Work." Mayo Clinic,

"Myths and Facts about COVID-19 Vaccines." Centers for Disease Control and Prevention,

"Myths and Truths | Coronavirus (COVID-19) Vaccines." Cincinnati Children's Hospital Medical Center,

Neergaard, Lauran, and Zeke Miller. "Fauci to Step down after Decades as Top US Infection Expert." The Associated Press, 22 Aug. 2022,

Offit, Dr. Paul. "Can MRNA Vaccines Alter a Person's DNA?" Children's Hospital of Philadelphia, 10 Feb. 2021,

O'Keefe, James. Twitter,

Ovide, Shira. "How to Reach the Unvaccinated." The New York Times, 10 Mar. 2021,

"Reaching Billions of People With COVID-19 Vaccine Information." Meta, 8 Feb. 2021,

The Different Types of COVID-19 Vaccines.

Tulp, Sophia. "Swedish Study on COVID Vaccines and DNA Misinterpreted." The Associated Press, 20 July 2022,

"Understanding COVID-19 MRNA Vaccines." National Human Genome Research Institute,

Weidenbacher, Payton A. B., et al. A Ferritin-Based COVID-19 Nanoparticle Vaccine That Elicits Robust, Durable, Broad-Spectrum Neutralizing Antisera in Non-Human Primates. bioRxiv, 26 Dec. 2022. bioRxiv,

"You Asked, We Answered: Can MRNA Vaccines Alter Human DNA?" Nebraska Medicine, 21 Dec. 2020,

Zuckerberg, Mark. Facebook,

Jordan Liles is a Senior Reporter who has been with Snopes since 2016.