Acute spinal paralysis after the administration of oral poliomyelitis vaccine in the Federal Republic of Germany (1963-1984)

Vaccine-associated paralytic poliomyelitis: a retrospective cohort study of acute flaccid paralyses in Brazil

BACKGROUND

At the present time, in Brazil and other countries in the Americas, the only cases of paralytic poliomyelitis due to poliovirus are caused by vaccine strains. The recognition of possible determinants of vaccine-associated paralytic poliomyelitis (VAPP) by public health surveillance and immunization programmes is relevant to inform the debate on criteria for case definition and vaccination strategies.

METHODS

A retrospective cohort study based on the cases of acute flaccid paralysis (AFP) reported to the Ministry of Health (MoH) was designed, with the objective of studying cases of VAPP in Brazil between 1989 and 1995. Clinical, laboratory and epidemiological data from 3656 acute flaccid paralysis (AFP) cases, 30 of them diagnosed as VAPP, were analysed.

RESULTS

An 8.88 risk ratio of VAPP (95% CI : 4.37-18.03) was found when comparing individuals who received oral poliovirus vaccine (OPV) between 4 and 40 days before the onset of paralysis and individuals who did not receive the vaccine within this period. A risk of 1 case/2.39 million first doses and 1 case/13.03 million OPV doses administered was estimated for the general population.

CONCLUSIONS

Cases of AFP who received OPV between 4 and 40 days before the onset of paralysis and had fever, a prodrome of gastrointestinal symptoms, history of first dose of OPV, isolation of vaccine poliovirus type 2, and young age deserve careful investigation, since they are at increased risk for the condition studied.

Epidemiological analysis of immunity to poliovirus after termination of an era of vaccination with OPV in Germany. An analysis of the German Association Against Viral Diseases (DVV)

The global eradication of poliomyelitis by the year 2000 is an objective of the World Health Organization (WHO). Since 1998, after a period of 37 years of vaccination using live oral poliovirus vaccine (OPV), single use of inactivated poliovirus vaccine (IPV) has been recommended in Germany. The present epidemiological analysis shows the immunity of 3474 patients to poliovirus types 1, 2 and 3 by using a microneutralization assay. A non-age-specific evaluation of antibodies seroprevalence to poliovirus type 1 remained 81% and similarly, for poliovirus type 2 86% while the poliovirus type 3 decreased from 78% in 1990-1992 to 68% in 1997. In the important group of children aged 5-14 years, the prevalence of antibodies to type 3 decreased clearly from 74% in 1990 to 47% in 1997. The relatively favorable level of seroprevalence of antibody to type 2 in children aged 1-4 years (89%) indicates a good acceptance of vaccination programs. However, a good immunity to all 3 serotypes was not achieved by primary vaccination. The objective of a global eradication of poliomyelitis has not yet been be achieved. Great problems still exist, especially in Africa and Asia.

Role of provocation poliomyelitis in vaccine-associated poliomyelitis

The impact of different vaccine administrations in the Federal Republic of Germany, in relation to vaccine-associated paralytic poliomyelitis (VAPP) was studied. (This only means that on the basis of the temporal relation of vaccination and onset, the vaccine cannot be ruled out as possible cause). Oral polio vaccine (OPV) was given between 1963 and 1977 only and recommended simultaneously with inactivated vaccines (DT/DPT) between 1980 and 1985. In the first period 10 VAPP cases occurred among 9.96 million estimated vaccinees aged under 2 years. In the second period 6 cases of provocation poliomyelitis (PRP) were found among 2.9 million estimated OPV/DT/DPT vaccinees of the same age group. Statistically the VAPP/PRP frequencies in the two periods studied did not achieve significance.

Rare adverse events associated with oral poliovirus vaccine in Brazil

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.