A new analysis of adverse events reported to the federal vaccine safety surveillance database after the HPV vaccine detected a strong safety signal for POTS, an autonomic nervous system disorder, in some people who received the shots.
The authors of the study, published last week in PLOS One, analyzed 77,909 reports associated with human papillomavirus (HPV) vaccines submitted to the Vaccine Adverse Event Reporting System (VAERS) between 2006 and 2024.
They concluded that the signal for postural orthostatic tachycardia syndrome (POTS) warranted further investigation. However, they downplayed the significance of their findings, according to experts who spoke with The Defender.
Their discussion section dedicated only two sentences to POTS, even though the condition was the strongest signal identified by the analysis.
The authors underscored that a signal for POTS does not prove that it was caused by the shot, and said that a strong signal “does not necessarily translate into a large clinical or public health impact.”
Warning that when people hear about serious adverse events, it affects their “perception” of safety, the authors framed their paper as part of a process of identifying and addressing potential risks that “is crucial to maintaining high vaccination coverage.”
Cynthia Nevison, Ph.D., said this approach led the authors to be dismissive of their own results. “I always object in principle to papers that start out with the motivation of reducing vaccine hesitancy,” Nevison told The Defender.
Children’s Health Defense (CHD) Chief Scientific Officer Brian Hooker said the attempts to downplay POTS as a side effect of the HPV shot are “criminal and the paper is expertly crafted to hide this very obvious signal in order to repeat the default ‘safe and effective’ lie.”
He added that given VAERS underreporting, “we know that the pesky result they’re downplaying could represent 68,000 POTS cases nationwide and over 1 million serious adverse events total.”
Did data really show ‘favorable’ overall safety of HPV vaccines?
Researchers from Xiamen University in China examined the reports using four statistical signal-detection methods commonly employed in pharmacovigilance to identify adverse events that are reported more often than expected.
They identified adverse event signals in the data, typically called “safety signals,” because they indicate a condition may be caused by the shot and warrant further investigation.
Syncope, or fainting, was the most frequently reported adverse event signal, with 8,351 reports. POTS showed the strongest statistical reporting signal, appearing in 680 reports.
Among all reports, 68.4% involved females and nearly half involved people younger than 18, the primary age group targeted for HPV vaccination. About 90% of reported adverse events occurred within 30 days of vaccination.
CHD Senior Research Scientist Karl Jablonowski said that according to the data in the paper, the proportion of POTS reports for non-HPV vaccines in the VAERS database is 1 in 9,950. For Gardasil, it is 1 in 475.
“For a passive surveillance system that captures the smallest fragment of actual adverse events, 1 in 475 is a huge number and is hugely out of proportion for all other vaccines,” he said.
Nevison, who has conducted her own analysis of adverse event reports for Gardasil in VAERS, questioned some of the authors’ numbers.
She counted over 12,000 reports of syncope from 2006-2025 in the U.S.-only VAERS dataset — well above the 8,351 cases identified by the authors, who deemed only 1,229 of those reports “serious.”
“The decision to label a report as ‘serious’ can be subjective and it’s not clear who is making this determination,” Nevison said. “When we recall that health officials during COVID routinely dismissed myocarditis reports as ‘mild,’ there is reason to be skeptical of these subjective judgments.”
She said this is particularly important, given that the authors concluded:
“Encouragingly, serious AEs [adverse events] account for only a small proportion of the reported HPV vaccine-related AEs. While the overall safety of the HPV vaccine is favorable, identifying and addressing potential risks is crucial to maintaining high vaccination coverage.”
“Again, the emphasis is on decreasing vaccine hesitancy and reassuring the public that safety is not an issue,” Nevison said. “On what basis are they claiming that ‘the overall safety … is favorable’? Such a statement requires a quantitative comparison of the number needed to harm vs. the number needed to treat for vaccine AEs and HPV-related conditions, respectively, of comparable severity. Zhang et al. haven’t done this.”

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The evidence for link between Gardasil and POTS
Merck has been aware of a link between Gardasil and POTS since at least 2011, according to expert reports submitted as part of a recent lawsuit against Merck by Jennifer Robi, a California woman who alleged the Gardasil vaccine permanently disabled her.
Yet, the company has never warned the public about the risk.
Robi and hundreds of other plaintiffs who alleged they suffered POTS and other serious adverse events after taking Gardasil recently settled with Merck on confidential terms. The expert reports submitted during the case are now public.
Several expert reports present evidence, including clinical cohorts, adverse event reports and autoimmune testing, that experts said support a probable connection between Gardasil and the development of POTS and certain autoimmune conditions.
Other reports showed how Merck cherry-picked vaccine injury data to try to prove its Gardasil HPV vaccine didn’t cause serious neurological side effects.
Numerous published studies have also linked Gardasil to autoimmune conditions and POTS.
Related articles in The Defender
- Merck Deliberately Hid Gardasil Link to Autoimmune Disorders, Says Former FDA Consultant
- CDC Relied on Cherry-picked Data to Claim No Link Between Merck’s Gardasil Vaccine and POTS
- Woman Confined to Wheelchair Settles With Merck Over HPV Vaccine Lawsuit
- Gardasil’s Long Shadow of Autoimmunity Confirmed — Again — by New Study
