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Rare adverse events associated with oral poliovirus vaccine in Brazil
1Departamento de Virologia, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brasil.
Abstract:
Oral poliovirus vaccine (OPV) developed by A. Sabin has been effectively used to control poliomyelitis in Brazil, and the last case with the isolation of a wild poliovirus strain occurred in March 1989. Although the vaccine controlled the circulation of wild strains and poliomyelitis cases associated with these strains were not detected during the last eight years, rare cases classified as vaccine-associated paralytic poliomyelitis (VAPP) have been detected. Molecular characterization studies of poliovirus strains isolated from VAPP cases and from healthy contacts have confirmed that the isolates are derived from the Sabin vaccine strains and also detected genomic modifications known or suspected to increase neurovirulence such as mutations and recombination. The molecular characterization of polioviruses isolated during the last eight years from paralysis cases classified as Guillain-Barré (GBS) syndrome and transverse myelitis (TM), and from facial paralysis (FP) cases also confirmed the vaccine origin of the strains and demonstrated mutations known to increase neurovirulence. Analysis of the epidemiologic data of these GBS, TM and FP cases demonstrated that in most of them the last OPV dose was given months or years before the onset of the disease and the isolation of the polioviruses. The temporal association between the isolation of these strains and the GBS, TM and FP suggested that the Sabin vaccine-derived poliovirus strains could also rarely trigger the diseases.
Insights
Oral poliovirus vaccine (OPV) has controlled polio in Brazil, but rare vaccine-associated paralytic poliomyelitis (VAPP) cases occur. Sabin vaccine-derived polioviruses, with neurovirulence mutations, may also trigger other neurological conditions like GBS, TM, and FP.
Area of Science:
- Virology
- Epidemiology
- Neuroscience
Background:
- Oral poliovirus vaccine (OPV) has been highly effective in controlling poliomyelitis in Brazil since 1989.
- Despite the absence of wild poliovirus strains, rare cases of vaccine-associated paralytic poliomyelitis (VAPP) continue to be detected.
Purpose of the Study:
- To investigate the origin and characteristics of poliovirus strains isolated from VAPP and other neurological cases.
- To explore the potential role of Sabin vaccine-derived polioviruses in triggering neurological conditions beyond poliomyelitis.
Main Methods:
- Molecular characterization of poliovirus strains isolated from patients with VAPP, Guillain-Barré syndrome (GBS), transverse myelitis (TM), and facial paralysis (FP).
- Analysis of genomic modifications associated with increased neurovirulence.
- Epidemiological analysis of vaccination history and disease onset in affected individuals.
Main Results:
- Polioviruses isolated from VAPP, GBS, TM, and FP cases were confirmed to be derived from Sabin vaccine strains.
- Genomic modifications known to increase neurovirulence were identified in these vaccine-derived strains.
- A temporal association suggests Sabin vaccine-derived polioviruses may rarely trigger GBS, TM, and FP, even when OPV administration was months or years prior.
Conclusions:
- Sabin vaccine-derived polioviruses, carrying mutations for neurovirulence, are responsible for VAPP.
- These vaccine-derived strains may also be implicated in rare instances of other neurological disorders like GBS, TM, and FP.
- The findings highlight the need for continued surveillance and molecular characterization of polioviruses in the post-eradication era.