Pólio: baixa cobertura vacinal e o risco iminente de novas infecções / Polio: low vaccination coverage and the imminent risk of new infections

A poliomielite, comumente chamada de pólio ou paralisia infantil, é uma doença viral altamente infecciosa que afeta principalmente crianças menores de 5 anos de idade. O vírus é transmitido de pessoa para pessoa, disseminado principalmente pela via fecal-oral ou, menos frequentemente, por fômites (água ou alimentos contaminados); sendo que o agente etiológico pode se espalhar rapidamente em áreas cujos sistemas de higiene e saneamento são precários. Também pode haver transmissão por meio de gotículas de secreções da garganta durante a fala, tosse ou espirro ( WHO, 20 22 a ; SBIm, 2022)

Polio, commonly called polio or infantile paralysis, is a highly infectious viral disease that primarily affects children under 5 years of age. The virus is transmitted from person to person, spread mainly by the fecal-oral route or, less frequently, by fomites (contaminated water or food); being that the agent etiologic disease can spread rapidly in areas where hygiene and sanitation systems are precarious. There may also be transmission through droplets of secretions from the throat during speech, coughing or sneezing (WHO, 20 22 a ; SBIm, 2022)

Comparison of microarray-predicted closest genomes to sequencing for poliovirus vaccine strain similarity and influenza A phylogeny.

We evaluate sequence data from the PathChip high-density hybridization array for epidemiological interpretation of detected pathogens. For influenza A, we derive similar relative outbreak clustering in phylogenetic trees from PathChip-derived compared to classical Sanger-derived sequences. For a positive polio detection, recent infection could be excluded based on vaccine strain similarity.

Highly divergent type 2 and 3 vaccine-derived polioviruses isolated from sewage in Tallinn, Estonia.

Highly divergent vaccine-derived polioviruses (VDPVs) have been isolated from sewage in Tallinn, Estonia, since 2002. Sequence analysis of VDPVs of serotypes 2 and 3 showed that they shared common noncapsid region recombination sites, indicating origination from a single trivalent oral polio vaccine dose, estimated to have been given between 1986 and 1998. The sewage isolates closely resemble VDPVs chronically excreted by persons with common variable immunodeficiency, but no chronic excretors have yet been identified in Estonia.

The human qualities needed to complete the global eradication of polio.

Although the 99% decrease seen in global polio incidence between 1988 and 2000 represented remarkable progress towards polio eradication, tackling the last 1% of polio has proved tantalizingly difficult. Pockets of endemic transmission currently persist both on the border between Afghanistan and Pakistan and in northern Nigeria. These pockets have permitted the reinfection of countries that were previously polio-free. Global strategic plans for polio eradication set out the activities, resources and financing needed to overcome the managerial, technical and security challenges faced by those tasked with the interruption of poliovirus transmission. However, polio eradication also depends on the less tangible but equally important human qualities of energy, realism, articulacy, determination, imagination, collaboration, adaptability, tactical awareness, innovation, openness and nimbleness (the initial letters of which give the acronym "ERADICATION"). By paying attention to these human qualities, the stakeholders involved may be more likely to achieve global polio eradication.

Même si la diminution de 99% de l'incidence mondiale de poliomyélite entre 1988 et 2000 a représenté un remarquable progrès vers l'éradication de la maladie, s'attaquer au dernier 1% de la polio s'est avéré terriblement difficile. Des poches de transmission endémique persistent actuellement à la frontière entre l'Afghanistan et le Pakistan et au nord du Nigeria. Ces poches ont permis la réinfection des pays qui ne présentaient auparavant plus aucun cas de poliomyélite. Les plans stratégiques mondiaux pour l'éradication de la poliomyélite ont établi les activités, les ressources et le financement nécessaires pour surmonter les défis techniques, de gestion et de sécurité que doivent relever les personnes chargées d'eradiquer la transmission du virus de la polio. Cependant, l'éradication de la maladie dépend aussi de qualités humaines moins tangibles, mais tout aussi importantes, qui sont l'énergie, le réalisme, la faculté d'expression, la détermination, l'imagination, la collaboration, l'adaptabilité, le sens tactique, l'innovation, la sincérité et la vivacité (dont les lettres initiales en anglais donnent l'acronyme «ERADICATION¼). En prêtant attention à ces qualités humaines, les parties prenantes pourront probablement réussir à éradiquer la poliomyélite à l'échelle mondiale.

Aunque la disminución del 99% en la incidencia de la poliomielitis a nivel global observada entre 1988 y 2000 representó un progreso notable hacia la erradicación de dicha enfermedad, hacer frente al último 1% ha resultado terriblemente difícil. En la actualidad persisten enclaves de transmisión endémica en la frontera entre Afganistán y Pakistán y en el norte de Nigeria. Dichos enclaves han permitido que países que ya se habían librado de la enfermedad se hayan vuelto a infectar. Los planes estratégicos globales para la erradicación de la poliomielitis establecen las actividades, los recursos y la financiación necesarios para vencer los retos administrativos, técnicos y de seguridad a los que hacen frente las personas cuya tarea es interrumpir la transmisión del poliovirus. No obstante, la erradicación de la poliomielitis también depende de cualidades humanas, menos palpables pero igual de importantes, como la energía, el realismo, la capacidad de expresión, la determinación y la imaginación, la colaboración, la flexibilidad, los conocimientos tácticos, la innovación, la franqueza y la agilidad (en inglés, las iniciales de estas palabras dan lugar a las siglas ERADICATION, erradicación en español). Si se presta atención a dichas cualidades humanas, las partes interesadas implicadas podrían tener más posibilidades de lograr la erradicación global de la poliomielitis.

[Immunity to poliomyelitis in adult population of Moscow region. Role of vaccine and wild polioviruses in its formation].

Assessment of immunity to poliomyelitis in adults from 8 towns of Moscow region was conducted. Low levels of population immunity against some serotypes of poliovirus in several towns have been found. At the same time, these levels were high and very high in other towns. Measurement of levels of strain-specific antibodies to vaccine and wild polioviruses demonstrated wide circulation of wild polioviruses during past decades which had significant influence on formation of immunity. Substantial number of non-immune adults represents favorable conditions for circulation of vaccine polioviruses after cessation of vaccination, which, in its turn, could result in reestablishment of their neurovirulent properties and subsequent reemergence of poliomyelitis.

Protective efficacy of a monovalent oral type 1 poliovirus vaccine: a case-control study.

BACKGROUND: A high-potency monovalent oral type 1 poliovirus vaccine (mOPV1) was developed in 2005 to tackle persistent poliovirus transmission in the last remaining infected countries. Our aim was to assess the efficacy of this vaccine in India. METHODS: We estimated the efficacy of mOPV1 used in supplementary immunisation activities from 2076 matched case-control pairs of confirmed cases of poliomyelitis caused by type 1 wild poliovirus and cases of non-polio acute flaccid paralysis in India. The effect of the introduction of mOPV1 on population immunity was calculated on the basis of estimates of vaccination coverage from data for non-polio acute flaccid paralysis. FINDINGS: In areas of persistent poliovirus transmission in Uttar Pradesh, the protective efficacy of mOPV1 was estimated to be 30% (95% CI 19-41) per dose against type 1 paralytic disease, compared with 11% (7-14) for the trivalent oral vaccine. 76-82% of children aged 0-23 months were estimated to be protected by vaccination against type 1 poliovirus at the end of 2006, compared with 59% at the end of 2004, before the introduction of mOPV1. INTERPRETATION: Under conditions where the efficacy of live-attenuated oral poliovirus vaccines is compromised by a high prevalence of diarrhoea and other infections, a dose of high-potency mOPV1 is almost three times more effective against type 1 poliomyelitis disease than is trivalent vaccine. Achieving high coverage with this new vaccine in areas of persistent poliovirus transmission should substantially improve the probability of rapidly eliminating transmission of the disease.

Developments in the production and quality control of poliovirus vaccines -- historical perspectives.

Using virus grown in monkey kidney cells, Salk and his colleagues developed an inactivated poliovirus vaccine (IPV) in 1952. A large-scale field trial showed the vaccine to be safe and highly immunogenic in children, but soon after the vaccine became generally available in 1955, cases of paralytic disease were reported in recipients. Investigations showed that almost all the cases occurred in children who had received vaccine from one particular manufacturer. Extensive studies attributed the disaster to problems with inactivation. Addition of a Seitz filtration step midway during formalin inactivation and extension of the inactivation period resulted in a safe vaccine. No further paralytic cases were observed following the use of several hundred million doses of this improved vaccine. Thus, IPV was safe and caused a dramatic decline in the incidence of poliomyelitis in countries where it was used. A second generation IPV is produced in fermentors using well-characterized cell strains or continuous cell lines. The major breakthrough in the development of live poliovirus vaccine was the application of tissue culture methods for virus attenuation. By 1959 several candidate live oral poliovirus vaccines (OPV) had been developed. These were clinically tested in millions of individuals and found to be safe and effective. Since the attenuated virus strains developed by Koprowski and Cox were more neurotropic in monkeys than the Sabin strains, only the latter was licensed in the USA in 1961 and endorsed shortly after by the World Health Organization (WHO). The widespread use of Sabin's OPV in many countries hastened the development of International Requirements by WHO for OPV in 1962 to define the criteria that ensured the uniformity of batches produced by different manufacturers. These have been updated continuously in light of new information and quality control procedures. Extensive field trials have shown the risk of OPV associated polio to be less than 0.3 per million doses administered.