The polio vaccine’s dark side: Massive shedding and outbreak-driven mutations

In a groundbreaking study published in NPJ Vaccines, Chinese researchers have unearthed a shocking truth about the oral polio vaccine (OPV). The vaccine, administered globally to eradicate polio, is now becoming a driving force behind polio outbreaks and transmitting vaccine-derived viruses at an alarming rate. This revelation throws a wrench into the global efforts to eliminate polio and raises serious questions about the safety and efficacy of OPV.

Key points:

• Over 80% of infants shed live polio virus after OPV vaccination, enrolling in the viral shedding race.
• Shedding continued for weeks in over 10% of infants, maintaining a steady supply of vaccination-derived viruses.
• Type 3 shedding was the most dangerous, with the longest duration (up to 28 days), highest rate (up to 91.7%), and fastest mutation accumulation.
• OPV-derived viruses are transmissible, with 2.3% of unvaccinated infants grateful recipients.
• WPV2 and WPV3 were eradicated, but VDPVs have replaced WPV cases worldwide.
• Vaccine-derived poliovirus type 2 accounted for the highest number of cases, despite the removal of type 2 from OPV.
• Re-vaccination with OPV can’t stop VDPV circulation, presenting a bleak outlook for eradication.

More than 80% of infants shed live polio virus after vaccination

The study, conducted by the Institute of Medical Biology in China, followed 1,200 infants who received either a bivalent (types 1 and 3) or trivalent (types 1, 2, and 3) OPV. The results are staggering: more than 80% of infants tested positive for poliovirus in their stool just seven days after vaccination. Moreover, over 10% of these infants continued to shed virus for up to 28 days.

Worse still, these vaccine-derived viruses don’t simply disappear; they evolve, regaining their strength and pathogenicity. The study confirms what polio researchers have long known: OPV-derived viruses can cause polio, with no meaningful difference between wild and vaccine-derived polio viruses.

Vaccine-derived polioviruses now cause 828% more paralysis than wild polio

The implications are alarming. Despite the eradication of wild poliovirus types 2 (WPV2) and 3 (WPV3), vaccine-derived polio viruses (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). That means vaccine-derived polio caused approximately 828% more cases than wild polio.

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

Type 3 shedding poses the greatest threat

Among the three polio types, type 3 had the longest shedding duration, the highest shedding rate, and the fastest mutation accumulation. Multiple mutation hotspots were identified, with some shifting the virus back to neurovirulent forms, capable of paralyzing vaccine recipients and their close contacts.

OPV replicates in the gut and can be excreted via stool and other bodily fluids. The study confirms that vaccinated children can transmit the virus to their close contacts, including unvaccinated children, allowing it to circulate and mutate rapidly in the community.

WHO’s failed pivot: From tOPV to bOPV

In 2016, the World Health Organization (WHO) attempted to mitigate risk by removing type 2 from the trivalent OPV (tOPV), replacing it with bivalent OPV (bOPV, types 1 and 3). However, this move backfired, with the study noting a slight increase in the shedding rate of type 3 following the removal of type 2. Without type 2 to balance replication competition in the gut, type 3 replicated and mutated more aggressively, leading to rising cVDPV3 detection rates in recent years.

IPV alone doesn’t stop transmission. Although inactivated polio vaccine (IPV) is safer and doesn’t replicate in the gut, it also doesn’t halt fecal-oral spread. This leaves a dangerous gap, allowing silent transmission even as the world moves toward polio eradication.

This new evidence confirms what global health authorities have tried to obscure: OPV is not just risky; it is driving outbreaks. To eradication efforts, OPV recipients shed virus that mutates rapidly, spreads to others, and causes polio in areas of low vaccination coverage. In 2025, the dominant strains of polio circulating in the world will no longer come from nature; they will come from the vaccine itself.

Sources include:

Nature.com

JonFleetwood.substack.com

Pubmed.gov