Hedy Tung

A recent Yale-led study investigating the biology of post-vaccination syndrome — a term used to describe persistent symptoms reported by a small subset of individuals following COVID-19 vaccination — has found itself at the center of a broader national debate on science, politics and public trust in vaccines.

The study was published as a preprint, meaning it has not yet undergone peer review, a critical step where independent experts evaluate the study’s methodology, analysis and conclusions to ensure accuracy and rigor before formal publication. Since its release on Feb. 25, the preprint by Akiko Iwasaki and Dr. Harlan Krumholz has drawn both praise and controversy. 

While the study emphasized its preliminary nature and small sample size, it has nonetheless been invoked by vaccine skeptics such as Elon Musk, senior advisor to President Donald Trump, as supposed evidence of vaccine harm. The incident has renewed concerns among researchers at Yale about how to navigate politically sensitive science — particularly in the current climate, where public confidence in vaccines and scientific institutions continues to waver. 

“Now more than ever, I think it is crucial to study the potential adverse events after vaccination with rigorous scientific approaches,” Iwasaki, Sterling Professor of Immunobiology, wrote in an email to the News. “Ultimately, we want to make vaccines safer for everyone in the future.”

The PVS preprint study, which analyzed immune markers in 42 individuals reporting persistent symptoms following COVID-19 vaccination, has faced both scrutiny and misinterpretation. 

Critics have pointed to the study’s small sample size, lack of control group and preprint status, raising concerns that its findings could be overstated or misinterpreted. Some scientists have expressed worry that releasing preliminary research on such a politically charged topic could inadvertently fuel vaccine fear, especially in online spaces where nuance is often lost. 

Supporters of the study, however, view it as a necessary step toward understanding a poorly defined condition and responding to the experiences of individuals reporting long-term post-vaccination symptoms. The controversy intensified when Musk reposted a tweet that included a screenshot of an article published on The Disinformation Chronicle. The tweet, which currently has 2.1 million views, read, “They are finally admitting ‘Long COVID’ is just vaccine injury.”

Iwasaki replied, tweeting “No. This is not what our study shows.”

Dr. Howard Forman, a professor of public health and management at Yale, acknowledged the controversy and the tension it reveals about science communication today.

According to Forman, the study has a narrow scope, and may not have results that are relevant to all mRNA vaccines. However, he pushed back against leaving the study unpublished just because it sparked controversy. 

“But choosing not to publish it because the results might be misused would be a mistake,” Forman said. “We don’t stop science because it’s inconvenient.”

Forman noted that the backlash was predictable in today’s information ecosystem, where scientific findings have been stripped of context and amplified for political ends. 

“People reacted very angrily on both sides,” he said. “And quite frankly, I think that’s to their detriment.”

For many scientists, however, the concern is not simply about how research is shared, but how it is interpreted. 

Mark Schlesinger, a professor of health policy at the School of Public Health, noted that public expectations around vaccines are often shaped by the belief that medical care should be risk-free. 

“There is never any kind of medical treatment that doesn’t do harm. It could be to a relatively small number of people, but some people will still have harms done to them,” Schlesinger said. “When people hear that the vaccine does some harm to some people, like that preprint that came out, because their expectations are almost unduly positive, hearing about any harm makes them feel like someone has either screwed up or lied to them.”

According to Schlesinger, skepticism expanded significantly during the pandemic as mRNA vaccines were introduced under emergency authorization, noting that concerns around the novelty of the technology were reasonable but often uninformed.

Schlesinger explained that before the COVID-19 pandemic, vaccine hesitancy in the United States was more commonly found among well-educated, politically liberal individuals, often rooted in skepticism toward the pharmaceutical industry. 

However, the introduction of mRNA vaccines during the pandemic contributed to a rise in vaccine hesitancy among more conservative and less formally educated groups. Concerns about the new technology, combined with political discourse and resistance to perceived government mandates fueled this shift, Schlesinger explained.

“Public sentiment around vaccines has been eroded by deliberate disinformation campaigns”, Dr. Caitlin Ryus, a Yale emergency physician and public health advocate, noted. “Now we’re seeing vaccine skepticism normalized, even in policy decisions.” 

Both Ryus and Schlesinger agree that while skepticism is still concentrated in specific groups, its growing visibility — especially on social media — has fueled anti-vaccine narratives in public discourse.

“I think it’s unfortunate that the last 70 years of dramatic vaccine development is coming into question at this point,” Forman stated. “When you get the same answer all the time and the research gives you the right answer consistently, the notion of going back and questioning that becomes less about skepticism and more about conspiracies.”

Critics of the administration have pointed to both the language and the actions of public health officials — such as Health and Human Services Secretary Robert F. Kennedy Jr. — as indicative of a growing anti-vaccine stance. 

Ryus said she sees signs of an increasing popularization of anti-vaccine rhetoric in both policy and leadership appointments.

“This administration has not only failed to correct misinformation, but in some cases, it’s legitimizing it,” she said. “That has real consequences.”

Forman, Schlesinger and Ryus each pointed to the importance of improving science communication, particularly as misinformation continues to circulate widely. They emphasized the need for communication that is accurate, accessible and sensitive to how scientific findings are interpreted by the public.

“We need to translate science into plain language,” Ryus said. “It needs to connect to people’s values and lived experience. That means leading with stories and not just data.”

Schlesinger pointed out that one major challenge is how to explain that all vaccines — and all treatments — carry some risk. 

“It becomes our obligation to help people deal with negative consequences,” he said, referencing the federal vaccine injury compensation fund. “Because if we’re going to mandate vaccination, we have to own the risks that come with it.”

In the case of the PVS study, Iwasaki said her team worked hard to communicate their findings responsibly, acknowledging limitations and sharing the research only after a careful review process.

“Unfortunately, our findings have been used by some to fuel misinformation,” Iwasaki said. “But all we can do is provide our own coverage of the study in a responsible manner.”

As debates over vaccine research and public trust continue, Yale experts underscored the importance of preserving scientific rigor and integrity — even when the findings are inconvenient or unpopular.

“It’s a delicate balance,” Ryus said. “But the answer isn’t silence. It’s better science, clearer communication, and the courage to speak up.”