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Thomas Jefferson president has ‘liked’ tweets critical of COVID-19 vaccines, among other controversial topics

In response to criticism: “What I did not understand was that by liking a tweet, it could be interpreted as endorsement of the thought expressed or the person expressing it ...," Mark Tykocinski said.

Thomas Jefferson University
Thomas Jefferson UniversityRead moreEd Newton

Mark Tykocinski, the president of Thomas Jefferson University and dean of its medical college, has used his Twitter account to “like” tweets that question the science of COVID-19 vaccines, call gender reassignment surgery “child mutilation,” and are critical of diversity offices on college campuses, among other controversial topics.

“Two years after their introduction, the mRNAs Covid vaccines have proven to be what we all should have expected,” said a Dec. 11 tweet by Alex Berenson, once called “the pandemic’s wrongest man” by the Atlantic. “Another in a long line of overhyped, rushed, profit-driven Big Pharma flops with weak long-term efficacy and a lousy side effect profile. ...”

That was one of nearly 30 Berenson tweets in the last year that Tykocinski, 70, a Yale-educated molecular immunologist and academic leader who was elevated from provost to president July 1, “liked,” using his account, which identifies him as president of Jefferson and dean of the Sidney Kimmel Medical College.

Referring to a case that’s become a cause célèbre for attacks on gender reassignment surgery for children, Tykocinski liked this tweet by Donald Trump Jr. that said: “Doctors lied and coerced a 13-year-old into an irreversible ‘gender affirming medical procedure.’ Now she is fighting back and suing them. Donate here to support the lawsuit and help stop child mutilation.”

And he’s liked a tweet that linked to a letter to the editor in the Wall Street Journal titled, “Diversity Czars Always Need to Find New Oppression.”

“Their salaries and authority depend on discovering or, if necessary, creating new groups of the oppressed and their oppressors and finding ever more microaggressions to pursue,” the author wrote.

Jefferson employees who have asked for anonymity because they fear retribution have approached The Inquirer with concerns about Tykocinski’s social media activity, given that it is on an account that clearly identifies him as Jefferson’s president.

“He’s welcome to his private views,” said one employee. “But broadcasting them on social media in his capacity as president of Jefferson shows questionable judgment and undermines Jefferson’s credibility as an institution of higher learning. Some of the views he endorses on his account call into question the university’s commitment to diversity and inclusion and would be hurtful to Jefferson’s trans-identifying students and students of color.”

» READ MORE: Thomas Jefferson University provost elevated to president under new structure

In response to Inquirer questions raising the criticism, Tykocinski, who has worked at Jefferson for 16 years, said in a statement that he “liked” tweets to bookmark them, “to learn more about the subject matter or the particular viewpoint.

“As a scientist, educator and administrator, I firmly believe that productive discourse is a foundational element of science, growth and education,” he wrote. “What I did not understand was that by liking a tweet, it could be interpreted as endorsement of the thought expressed or the person expressing it. ... I certainly had no intention of endorsing the content of individual tweets or the person tweeting.

“I regret my lack of understanding of how ‘liking’ a tweet is an implied endorsement. I also regret how my lack of understanding of the Twitter platform caused some to question my views on these complex issues.”

The president, with only 108 followers on his year-old account that he created and maintains — “President, @jeffersonuniv and Dean of the Sidney Kimmel Medical College, Husband, dad, grandfather to 10 and cyclist” — uses it largely to support Jefferson sports teams, research, and employee and student honors.

He’s not a prolific tweeter: He’s tweeted 85 times total; in April, his five tweets were all retweets. The last time he wrote his own tweet was March 17, a congratulatory message to medical students. But he regularly likes tweets: 539 since he started his account, including one about students on Match Day, a photo of a rainbow, and a Thomas Jefferson commercial. A few of the hundreds of tweets he liked could be classified as legitimate scientific discussion about COVID vaccines, but many, however, represent controversial stances.

Tykocinski, who got his medical degree at New York University, previously worked at the University of Pennsylvania for a decade, and before that, he spent 15 years at Case Western Reserve University, where he was founding director of its Gene Therapy Facility. He was key in the transition when Thomas Jefferson merged with the former Philadelphia University in 2017.

» READ MORE: Jefferson-Philadelphia University merger drawing attention from other schools

‘It’s an anti-public health message’

It’s incumbent on a university president and medical college dean not to spread information that contradicts prevailing science, said Paul Offit, a medical doctor, professor of pediatrics, and the director of the Vaccine Education Center at Children’s Hospital of Philadelphia.

“When you’re in a position like that, there comes with it a certain responsibility and that responsibility is to stick with the science, to support the science,” said Offit. “You have abundant evidence that what he is supporting by linking to it on his site has been clearly refuted. Vaccines do work to keep people out of the hospital and to keep people out of the intensive care unit, and out of the morgue.”

After reviewing Tykocinski’s “likes” history, Offit said: “It’s an anti-public health message that he puts out there.”

Other examples of Tykocinski’s “likes” include:

  1. On Dec. 24, he liked a tweet by Toby Young, a British commentator who created the blog, called by MediaBias/Fact Check “a far-right biased quackery level pseudoscience website that frequently publishes false and misleading information regarding COVID-19 and science in general.” The tweet was about the vaccination of pregnant women leading to neonatal deaths, linking to an article in The Centers for Disease Control and Prevention recommends that pregnant women get vaccinated.

  1. Also on Dec. 24, he liked this tweet by Berenson, the former New York Times reporter once suspended from Twitter for violating its COVID-19 misinformation rules, but was reinstated after he sued: “2021 was the year the mRNAs failed us. 2022 was the year we failed ourselves, by doubling down after we’d already lost. 2023 will be the year we find out how high a price we pay.”

  2. Tykocinski also repeatedly has liked dozens of tweets by Twitter CEO Elon Musk, a polarizing figure, and Michael Shellenberger, who has been critical of climate change research; he is the author of Apocalypse Never: Why Environmental Alarmism Hurts Us All.

  3. And from Dec. 27, he liked this tweet from Libs of Tik Tok, which has been described as a far-right, anti-LGBTQ+ Twitter account: BREAKING: Florida Department of Business and Professional Regulation just announced they are investigating the “Drag Queen Christmas” all-ages drag show which took place yesterday. “Exposing children to sexually explicit activity is a crime in Florida”

Tykocinksi said Thursday when asked whether he regarded transgender surgery as child mutilation: “This is not my clinical area of expertise. In general, any issue involving children should be referred to clinical experts at children’s hospitals who offer the full complement of services necessary.” Jefferson Health provides gender-affirming care, according to its spokesperson.

In response to a question about the importance of diversity efforts on college campuses, he said diversity is “extremely important to him” and that the university has worked in this area on many fronts and does have an office of diversity and equity.

Regarding COVID-19 vaccines, he wrote: “I do not believe vaccines are harmful. The COVID-19 mRNA vaccines were originally made available through an accelerated [emergency use authorization] process: and hence, the speed in which they were developed saves millions of lives. There is still much to be learned. Academic institutions play a key role in answering these questions.”

COVID-19 vaccines have been shown to be safe and effective in preventing serious illness and death during the pandemic. But politics shaped how many Americans responded to guidance on shots and subsequent boosters, and their views on government’s role in mandating safety measures in response to the pandemic. Some conservative leaders emerged as vocal skeptics after the vaccines were rolled out. Polling has shown that Republicans are less likely to get fully vaccinated than Democrats.

A ‘who’s who list of all the typical COVID misinformation peddlers’

Jonathan Zimmerman, a professor of the history of education at the University of Pennsylvania who has ardently defended free speech rights, said he’s generally not in favor of scrutinizing academics’ digital footprint for alleged missteps. But, he said it’s different when it’s the president of a college, because people will presume he or she is speaking for that institution.

“If he liked those tweets because he agrees with Alex Berenson, that is a dagger at the heart of the scientific enterprise,” Zimmerman said. “There’s no other way to describe it.”

Jessica McDonald, science editor for, which is based at the Annenberg Public Policy Center of the University of Pennsylvania, reviewed Tykocinski’s “like” history at The Inquirer’s request. She said the list included some whom she described as a “who’s who list of all the typical COVID misinformation peddlers that we see.”

“At minimum, they are leaving out important information such as the vaccines actually work very well against severe disease and death, and that they’re quite safe, with only a few rare serious side effects.”

Although there are many examples of employees being disciplined for tweets they authored, liking tweets that contradict an employer’s values also has been reason for termination, including in the case of a Toronto Marlies hockey coach who had allegedly liked tweets in support of the Jan. 6 Capitol attack in Washington, and others that were transphobic and anti-vax.

Employees can be fired for conduct that harms a company’s reputation, wrote Lluc Cerda, an employment lawyer and partner at Samfiru Tumarkin LLP, a Canadian law firm, in a 2021 piece for Global News.

“Factors a court will consider include whether the employee had a public-facing role, including one that dealt with clients and suppliers, or if they managed others,” the lawyer wrote. “The more senior the employee, the higher the standard of conduct that’s usually expected.”

Staff writer Tom Avril contributed to this article.