Acute Flaccid Paralysis in a Vaccinated Child With Primary Immunodeficiency: Difficulties With Diagnostics of Vaccine-Associated Paralytic Poliomyelitis

Oral polio vaccine (OPV) from attenuated Sabin strains widely used for poliomyelitis prevention and eradication along with undeniable advantages has significant disadvantages, one of which is the ability to cause cases of vaccine-associated paralytic poliomyelitis (VAPP). Inactivated poliovirus vaccine (IPV) introduction into the national immunization schedules of countries that continue to use OPV allows effective prevention of VAPP cases and simultaneously forms immunity to PV type 2. The present study presents an example of VAPP development in a child with Bruton's disease, born by in vitro fertilization, vaccinated with four IPV doses followed by one bOPV dose, and paralysis onset 52 days bOPV vaccination. Despite objective clinical, laboratory and instrumental signs of anterior corneal myelitis, the isolation of Sabin-like poliovirus, and contradictory results of serological investigation, diagnostics caused significant difficulties for the treating physicians. The case was associated with a recombinant poliovirus of vaccine Sabin strains types 3 and 1 with a recombination point in 2C-encoding genome region, containing known neurovirulence reverse mutations and some unique ones. The introduction of IPV doses for primary immunization increases the safety of immunization against polio; however, while OPV is in use there is still a VAPP threat for immunocompromised children and unvaccinated contacts. © 2025 Wiley Periodicals LLC.