Poliovirus immunity among adults in the Democratic Republic of the Congo: a cross-sectional serosurvey

Background Vaccination efforts to eradicate polio currently focus on children under 5 years of age, among whom most cases of poliomyelitis still occur. However, in the Democratic Republic of the Congo (DRC), an outbreak of wild poliovirus type 1 occurred in 2010–2011 in which 16% of cases occurred among adults; in a related outbreak in the neighboring Republic of Congo, 75% of cases occurred among the same adult age-group. Given that infected adults may transmit poliovirus, this study was designed to assess adult immunity against polioviruses. Methods We assessed poliovirus seroprevalence using dried blood spots from 5,526 adults aged 15–59 years from the 2013–2014 Demographic and Health Survey in the DRC. Results Among adults in the DRC, 74%, 72%, and 57% were seropositive for neutralizing antibodies for poliovirus types 1, 2, and 3, respectively. For all three serotypes, seroprevalence tended to be higher among older age groups, those living in households with more children, and among women. Conclusions Protection against poliovirus is generally low among adults in the DRC, particularly for type 3 poliovirus. The lack of acquired immunity in adults suggests a potentially limited poliovirus circulation over the lifetime of those surveyed (spanning 1954 through 2014) and transmission of vaccine-derived poliovirus in this age group while underscoring the risk of these outbreaks among adults in the DRC.

Mucosal immunity to poliovirus

A cornerstone of the global initiative to eradicate polio is the widespread use of live and inactivated poliovirus vaccines in extensive public health campaigns designed to prevent the development of paralytic disease and interrupt transmission of the virus. Central to these efforts is the goal of inducing mucosal immunity able to limit virus replication in the intestine. Recent clinical trials have evaluated new combined regimens of poliovirus vaccines, and demonstrated clear differences in their ability to restrict virus shedding in stool after oral challenge with live virus. Analyses of mucosal immunity accompanying these trials support a critical role for enteric neutralizing IgA in limiting the magnitude and duration of virus shedding. This review summarizes key findings in vaccine-induced intestinal immunity to poliovirus in infants, older children, and adults. The impact of immunization on development and maintenance of protective immunity to poliovirus and the implications for global eradication are discussed.

Advax-CpG Adjuvant Provides Antigen Dose-Sparing and Enhanced Immunogenicity for Inactivated Poliomyelitis Virus Vaccines

Global immunization campaigns have resulted in a major decline in the global incidence of polio cases, with wild-type poliovirus remaining endemic in only two countries. Live oral polio vaccine (OPV) played a role in the reduction in polio case numbers; however, the risk of OPV developing into circulating vaccine-derived poliovirus makes it unsuitable for eradication programs. Trivalent inactivated polio virus (TIPV) vaccines which contain formalin-inactivated antigens produced from virulent types 1, 2 and 3 reference polio strains grown in Vero monkey kidney cells have been advocated as a replacement for OPV; however, TIPVs have weak immunogenicity and multiple boosts are required before peak neutralizing titers are reached. This study examined whether the incorporation of the novel polysaccharide adjuvant, Advax-CpG, could boost the immunogenicity of two TIPV vaccines, (i) a commercially available polio vaccine (IPOL®, Sanofi Pasteur) and (ii) a new TIPV formulation developed by Statens Serum Institut (SSI). Mice were immunized intramuscularly based on recommended vaccine dosage schedules and serum antibody titers were followed for 12 months post-immunization. Advax-CpG significantly enhanced the long-term immunogenicity of both TIPV vaccines and had at least a 10-fold antigen dose-sparing effect. An exception was the poor ability of the SSI TIPV to induce serotype type 1 neutralizing antibodies. Immunization with monovalent IPVs suggested that the low type 1 response to TIPV may be due to antigen competition when the type 1 antigen was co-formulated with the type 2 and 3 antigens. This study provides valuable insights into the complexity of the formulation of multivalent polio vaccines and supports the further development of adjuvanted antigen-sparing TIPV vaccines in the fight to eradicate polio.

Polio-like deformity: a diagnostic dilemma

ABSTRACT BACKGROUND: Significant advances have been made in the global effort to eradicate polio. Vaccine-associated poliovirus, or other enteroviruses, may still affect the anterior horn cell and cause acute flaccid paralysis. Following the acute disease, residual paralysis results in lower motor neuron weakness, altered growth and deformity. Our study aims to describe the clinical manifestations of a group of children that mimic that of classic paralytic poliomyelitis METHODS: We identified six children from our paediatric orthopaedic database that presented with polio-like deformities. Their clinical and imaging records were reviewed and described, together with the clinical manifestations of paralytic poliomyelitis RESULTS: Limb hypoplasia, pathological gait patterns and foot deformities were consistent features. The median leg length discrepancy was 2.5 cm (range 2-4 cm). The gait patterns observed included a Trendelenburg gait in 33% (n=2), a short limb gait in 50% (n=3), and one case with a combination of Trendelenburg, short limb and steppage gait. Tensor fascia lata contracture was present in 50% (n=3) of our patients. Foot deformities ranged from calcaneo-cavo-valgus to equino-cavo-varus deformities CONCLUSION: Despite significant advances made in the global fight to eradicate polio, we still see children with clinical manifestations reminiscent of the disease. Orthopaedic surgeons should remain familiar with the assessment and diagnosis of the sequelae of paralytic poliomyelitis Level of evidence: Level 5 Keywords: poliomyelitis, vaccine-associated paralytic poliomyelitis, polio-like deformity, acute flaccid paralysis

ACUTE FLACCID PARALYSIS REGISTERED FOR THE PERIOD 2012-2020, IN STARA ZAGORA REGION

Acute Flaccid Paralysis (AFP) is a clinical syndrome. There are many infectious and non-infectious causes of AFP. Poliomyelitis caused by the wild polio virus (the natural circulating strain of polio) is one of the causes of AFP. As a part of the worldwide campaign to eradicate polio, all countries do surveillance for polio by looking for clinical cases of AFP. The purpose of the study is to describe the cases of Acute Flaccid Paralysis, without Paresis Nervi facialis, in the Stara Zagora region for the period 2012-2020. Methods: A retrospective, descriptive analysis was performed on the parameters: diagnosis, seasonality, sex, residence, age, clinical data, and comorbidities, results of follow-up examinations, polio vaccine administration, and timeliness of studies. Results: There were 9 cases of AFP, without Paresis nervi facialis, registered and reported for the Stara Zagora region, for the period 2012 – 2020. The children in 3 years old were more affected- 4 patients. About the coverage with polio vaccine: 7 of the patients had 4 doses, 1- had 6 doses, 1 child had 5 doses, and + 1 zero dose. 100% of children are covered, according to their age, with IPV. Follow-up in 6 of the patients is without residual paresis and complications. Residual paresis was found in 1 of the cases. In 2 patients no control examination was performed due to migration. Conclusion: The correct epidemiological diagnosis is the way to timely and corrects clinical diagnosis. AFP Surveillance is of particular importance as well as fecal sampling up to 48 hours, from the onset of paralysis, and follow-up after the 60th day in children <15 years.

Reported Polio cases in Pakistan during 2019

This report describes polio cases, vaccination uncertainty and challenges, and the way forward to eradicate polio from Pakistan. Numerous articles, government and non-government documents, and survey reports were studied and an online search was made to collect information on polio in Pakistan. Once again the polio vaccination program has been stopped and accused by the local community in Pakistan as a result an increase has been seen in polio cases in the last year. In 2019, a total of 117 wild poliovirus (WPV) and 18 circulating vaccine-derived poliovirus (cVDPV2) cases were reported from the country. The majority of cases were from the Khyber Pakhtunkhwa (KP) province as a result of polio vaccination uncertainty and many challenges faced by the vaccination program in the region. Pakistan reported their highest annual number of WPV cases as compared to last few years. This increase is not only an alarming threat for the country but also a key challenge for the global polio eradication movement. Increase awareness and raising immunization to over 100% in some areas especially in the remote area where every year many children missed vaccination to achieve global polio eradication goals.