80% of Infants Shed Live Polio Virus After Vaccination—Mutated Vaccine Strains Now Cause 828% More Paralysis Than Wild Polio: Journal 'NPJ Vaccines'

Shedding of vaccine virus continued for weeks in over 10% of infants.

A new peer-reviewed study confirms what public health officials have long downplayed: Oral Polio Vaccine (OPV) recipients are shedding mutated vaccine viruses into the environment—pathogens that can regain neurovirulence and spark outbreaks of vaccine-derived paralytic polio.

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Neurovirulence is the ability of a virus to cause disease or pathology in the nervous system.

The findings, published yesterday in NPJ Vaccines, come from China’s Institute of Medical Biology and involve 1,200 infants in a first-of-its-kind trial analyzing viral shedding and genetic mutation patterns after OPV and IPV (Inactivated Poliovirus Vaccine) immunization.

The study reports that “more than 80% of infants in each group, who received the initial dose of bOPV or tOPV, tested positive for poliovirus in their stool" on day 7.”

It also notes that “over 10% of infants continued to shed poliovirus” up to day 28.

And the implications are alarming: Not only are children shedding vaccine poliovirus, but the shed virus frequently mutates back toward wild-type pathogenicity—what the paper confirms as genetic reversion to neurotoxicity.

Vaccine Shedding Is Driving Global Polio Outbreaks

Despite the eradication of wild poliovirus type 2 (WPV2) and type 3 (WPV3), vaccine-derived polioviruses (VDPVs) are now the primary cause of polio outbreaks worldwide.

Between 2018 and 2023, there were only 397 wild poliovirus cases globally—but 3,684 cases caused by circulating vaccine-derived strains (cVDPV), most of them type 2.

That means vaccine-derived poliovirus caused approximately 828% more cases than wild poliovirus between 2018 and 2023.

“The majority of global paralytic poliomyelitis cases are now attributed to poliovirus shedding from OPV rather than WPV,” the study states.

Type 3 Shedding Was the Most Dangerous

Among the three polio types, type 3 had the longest shedding duration, the highest shedding rate (up to 91.7%), and the fastest mutation accumulation.

Researchers found multiple mutation “hotspots” that produced amino acid changes capable of reversing vaccine attenuation:

• Type 1: Mutation rates as high as 74.2% (nt480) and 67.7% (nt525)

• Type 2: 100% of strains mutated at nt481

• Type 3: 91.7% mutation rate at nt472, with high rates at nt2034 and nt2636—some reverting to neurotoxic forms

These are not minor sequence changes—they’re the kind of shifts that can transform an allegedly harmless vaccine virus into one that paralyzes.

OPV Can Spread Person to Person

OPV replicates in the gut and is excreted via stool and other bodily fluids.

The study confirms that vaccinated children, even in clinical settings, shed the virus to the environment—and their close contacts, including unvaccinated children, can acquire and shed the virus themselves.

In one cited study, 42.2% of infants who received OPV shed the virus, but so did 2.3% of those who never received the vaccine, showing OPV-derived viruses are transmissible.

Once circulating, these strains mutate rapidly.

“The most important attenuation sites are located in the 5’NCR, and the 3D region is crucial for RNA replication,” the paper explains, “making them prone to rapid reversion.”

WHO’s Failed Pivot: From tOPV to bOPV

In 2016, the World Health Organization attempted to mitigate risk by removing type 2 from the trivalent oral polio vaccine (tOPV), replacing it with bivalent OPV (bOPV, types 1 and 3).

The move backfired.

“We observed a slight increase in the shedding rate of type 3 following the removal of type 2,” the authors admit.

Without type 2 to balance replication competition in the gut, type 3 appears to replicate and mutate more aggressively.

This loss of inter-serotype suppression may explain rising cVDPV3 detection rates in recent years.

IPV Alone Doesn’t Stop Transmission

Though IPV is said to be less dangerous—it doesn’t replicate in the gut—it also doesn’t stop fecal-oral spread.

“IPV has been shown to induce only limited primary intestinal immunity and does not effectively halt viral replication,” the study states.

This leaves a dangerous gap.

Countries switching from OPV to IPV risk losing mucosal immunity and allowing silent transmission—even as the world moves toward polio eradication.

Bottom Line

This new evidence confirms what global health authorities have tried to obscure: OPV is not just risky—it is driving outbreaks.

• OPV recipients shed virus.

• That virus mutates rapidly, often reverting to neurovirulence.

• It spreads to others, including the unvaccinated.

• And in areas of poor coverage, it causes polio.

In 2025, the dominant strains of polio circulating in the world no longer come from nature—they come from the vaccine itself.

Follow Jon Fleetwood: Instagram @realjonfleetwood / Twitter @JonMFleetwood / Facebook @realjonfleetwood

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