Administration Of Oral Polio Vaccine Research Articles

Comparative analysis of poliovirus-specific IgA and cytokine levels in the sera of Ascaris lumbricoides-infected and helminth-negative Nigerian children after oral poliovirus vaccination

Background: Intestinal helminth infection is associated with altered immune responses and compromised vaccine efficacy in infected children. Altered immune response due to Ascaris lumbricoides infection may compromise efficacy of oral poliovirus vaccination in children. There is no information on humoral immune response during oral poliovirus (OP) vaccination of A. lumbricoides–infected Nigerian children. The objective of this study is to determine the serum levels of cytokines (tumour necrosis factor–alpha TNF-α, interferongamma IFN–γ, interleukins -4, -6, -8, -10) and poliovirus-specific IgA (PV-IgA) antibody in children infected with A. lumbricoides compared with helminth-negative children (control) before and after oral poliovirus vaccination.
 Methodology: Twenty-three A. lumbricoides-infected children between ages 5-15 years (13 males and 10 females) and 23 age (4-15 years) and sex-matched helminth-negative children who met selection criteria were enrolled into the study after ethical approval and informed consent. Their stool samples were examined for helminth ova using concentration technique. Sera were collected before and 3 weeks after OP vaccinations, and serum concentrations of IFN–γ, TNF–α, IL-4, -6, -8, -10, and poliovirus-specific IgA concentrations were determined by enzyme-linked immunosorbent assay. The level of statistical significance was set at α0.05.
 Results: Pre-vaccination serum levels of IFN–γ, IL–4, IL-6 and IL-8 were significantly higher in A. lumbricoides–infected children compared with pre-vaccination levels in helminth-negative children. Postvaccination serum levels of IFN–γ, IL–4 and IL-8 were significantly higher in A. lumbricoides–infected children compared with post-vaccination serum levels in helminth-negative children. In the A. lumbricoides-infected children, pre-vaccination serum levels of IL-6 and IL-8 were significantly higher compared with post vaccination levels while pre-vaccination serum levels of IFN–γ, IL–4 and IL-8 were significantly higher in helminth-negative children compared with the post-vaccination levels. There was no significant reduction in post-vaccination median serum level of PV-IgA compared with level before vaccination in A. lumbricoides-infected children. Also, there was no significant increase in post-vaccination median serum level of PV-IgA compared with level before vaccination in helminth-negative children.
 Conclusion: Oral polio vaccine administration caused decrease expression of inflammatory cytokines (IL-6 and IL-8) in A. lumbricoides-infected school children, and A. lumbricoides infection may reduce PV-IgA production following OP vaccination.
 Keywords: Ascaris lumbricoides infection, cytokines, children, poliovirus vaccination

Reduced Mortality After Oral Polio Vaccination and Increased Mortality After Diphtheria-tetanus-pertussis Vaccination in Children in a Low-income Setting

PurposeThe diphtheria-tetanus-pertussis vaccine (DTP) and oral polio vaccine (OPV) were introduced in children 3 of 5 months of age in 1981–1983 in Bandim, in the capital of Guinea-Bissau. Because DTP has been linked to deleterious nonspecific effects (NSEs) and OPV to beneficial NSEs, we followed up this cohort to 3 years of age and examined the effects of DTP with OPV on all-cause mortality and the interactions of DTP and OPV with the measles vaccine (MV). MethodsDTP and OPV were offered at 3 monthly community weighing sessions. Vaccination groups were defined by the last vaccine received. We compared overall mortality for different groups in Cox proportional hazards regression models, reporting hazards ratios (HRs) with 95% CIs. FindingsThe study cohort included 1491 children born in Bandim from December 1980 to December 1983. From 3 to 35 months of age, with censoring for MV, children vaccinated with DTP and/or OPV had higher mortality than both unvaccinated children (HR = l.66; 95% CI, 1.03–2.69) and OPV-only vaccinated children (HR = 2.81; 95% CI, 1.02–7.69); DTP-only vaccinated children had higher mortality than OPV-only vaccinated children (HR = 3.38; 95% CI, 1.15-–9.93). In the age group of 3–8 months, before MV is administered, DTP-only vaccination was associated with a higher mortality than DTP with OPV (HR = 3.38; 95% CI, 1.59–7.20). Between 9 and 35 months of age, when MV is given, DTP-vaccinated and MV-unvaccinated children had higher mortality (HR = 2.76; 95% CI, 1.36–5.59) than children who had received MV after DTP, and among children who received DTP with MV or after MV, DTP-only vaccination was associated with a higher mortality than DTP with OPV (HR = 6.25; 95% CI, 2.55–15.37). ImplicationsBecause the 2 vaccines had differential effects and the healthiest children were vaccinated first, selection biases are unlikely to explain the estimated impact on child survival. OPV had beneficial NSEs, and administration of OPV with DTP may have reduced the negative effects of DTP.

Immunisation compliance and incidence of adverse events

Introduction: Immunization coverage rate is the percentage of the target population that has received the last recommended dose for each vaccine recommended in the national schedule and is one of the best indicators of public health outcome and service and vaccines are important tools in preventing infectious diseases. Aim and Objective: The aim and objective were to assess the immunization compliance and adverse event following immunization (AEFI). Methodology: The present retroprospective observational study was carried out by collecting response of prevalidated immunization compliance and adverse event questionnaire from parents who brought their children for vaccination up to the age of 5 years. This survey asked about immunization compliance and AEFI. Results: A total of 188 randomly selected parents were interviewed about their child's immunization compliance and AEFI. Out of the selected parents, 86.17% agreed for the necessity of vaccines against vaccine preventable disease (VPD) and 13.83% were unaware of the necessity of vaccination. Knowledge about severity of VPDs was known to only 56.38% of parents and 13.82% of parents did not have knowledge of severity or harmfulness of VPDs. Approximately 71.8% of parents were good compliant, while 28.2% were some compliant with immunization schedule during the 6 months of the study period. Discussion: Missed opportunities resulted in subsequent late immunization. The most common errors occurring in this sample were missed opportunities for Bacillus Calmette–Guerin (BCG) vaccination, as most of the children did not get BCG vaccination at birth and superfluous administration of oral polio vaccine observed due to the National Pulse Polio Immunization Program. A consequence of not adhering to the recommended childhood immunization schedule was that doses were given too late. Conclusion: Efforts to improve compliance with immunization schedule are recommended to optimize VPDs.

Validation of a High-throughput, Multiplex, Real-time Qualitative Polymerase Chain Reaction Assay for the Detection of Sabin Oral Polio Vaccine in Environmental Samples.

BackgroundCurrently, the primary mechanism for poliovirus detection is acute flaccid paralysis (AFP) surveillance, with environmental sampling serving as a complement. However, as AFP cases drop, environmental surveillance will become increasingly critical for poliovirus detection. Mexico provides a natural environment to study oral polio vaccine (OPV) transmission, as it provides routine injected polio vaccine immunization and biannual OPV campaigns in February and May.MethodsAs part of a study of OPV transmission in which 155 children were vaccinated with OPV, monthly sewage samples were collected from rivers leading from 3 indigenous Mexican villages (Capoluca, Campo Grande, and Tuxpanguillo) from February to May 2015. Samples were also collected from October 2015 to October 2017, during which time there were standard OPV campaigns. Samples were analyzed for the presence of OPV serotypes, using a real-time qualitative polymerase chain reaction assay capable of detecting as few as 9, 12, and 10 copies/100 µL of viral ribonucleic acid for OPV serotypes 1, 2, and 3 (OPV-1, -2, and -3), respectively. Included here are 54 samples, taken up to November 2016.ResultsOf the 54 samples, 13 (24%) were positive for OPV. After the vaccination of 155 children in February 2015, OPV was found 2 months after vaccination. After unrestricted OPV administration in February 2016, OPV was detected in sewage up to 8 months after vaccination. OPV-3 was found in 11 of the 13 positive samples (85%), OPV-2 was found in 3 positive samples (23%), and OPV-1 was found in 1 sample (8%).ConclusionsOPV can be detected even when small amounts of the vaccine are introduced into a community, as shown by OPV-positive sewage samples even when only 155 children were vaccinated. When OPV vaccination was unrestricted, sewage samples were positive up to 8 months after vaccination, implying community OPV circulation for at least 8 months. OPV-3 was the serotype most found in these samples, indicating prolonged transmission of OPV-3 when compared to the other serotypes. Future work could compare the phylogenetic variance of OPV isolates from sewage after OPV vaccinations.

Vaccine-associated paralytic poliomyelitis in the Russian Federation in 1998–2014

ObjectivesDifferent polio vaccination schemes have been used in Russia: oral polio vaccine (OPV) was used in 1998–2007 and inactivated polio vaccine (IPV) followed by OPV in 2008–2014. This article presents the characteristics of vaccine-associated paralytic poliomyelitis (VAPP) cases in Russia during this period. MethodsVAPP cases were identified through the acute flaccid paralysis surveillance system, classified by the National Expert Classification Committee. Criteria for a ‘recipient VAPP’ (rVAPP) case were poliomyelitis symptoms 6–30days after OPV administration, isolation of the vaccine virus, and residual paralysis 60days after disease onset. Unvaccinated cases with a similar picture 6–60days after contact with an OPV recipient were classified as ‘contact VAPP’ (cVAPP) cases. ResultsDuring 1998–2014, 127 VAPP cases were registered: 82 rVAPP and 45 cVAPP. During the period in which only OPV was used, rVAPP cases prevailed (73.8%); cases of rVAPP were reduced during the sequential scheme period (15%). Poliovirus type 3 (39.5%) and type 2 (23.7%) were isolated more often. Vaccine-derived poliovirus types 1, 2, and 3 were isolated from three cases of cVAPP. The incidence of VAPP cases was higher during the period of OPV use (1 case/1.59 million OPV doses) than during the sequential scheme period (1 case/4.18 million doses). ConclusionThe risk of VAPP exists if OPV remains in the vaccination schedule.

Digital immunization registry: evidence for the impact of mHealth on enhancing the immunization system and improving immunization coverage for children under one year old in Vietnam.

The Vietnam National Expanded Program on Immunization (NEPI) has been successfully implementing a nationwide immunization system since 1985. From the start, the program has increased the immunization coverage rate; however, data on immunization coverage in Vietnam are gathered and aggregated from commune health centers in routine, paper-based reports, which have shortcomings. Also, calculations of coverage are inconsistent at subnational levels, which lead to uncertainty about the size of the target population used as the denominator in coverage calculations. The growth of mobile networks in Vietnam provides an opportunity to apply mHealth to improve the immunization program. In 2012, PATH and the Vietnam NEPI developed and piloted a digital immunization registry, ImmReg, to overcome the challenges of the paper system. A final evaluation was conducted in 2015 to assess the impact of ImmReg, including its use of SMS reminders, on improving the immunization program. The study population comprised all children born in Ben Tre province in September and October of 2013, 2014, and 2015, representing pre-intervention, post-intervention, and one year post-intervention, respectively. Data exported from ImmReg were used to compare the immunization rate, dropout rate, and timeliness of vaccination before and after the intervention. Additionally, a rapid survey was conducted to understand the willingness of parents with children due for vaccination to pay for SMS reminder messages on the immunization schedule. Timely administration of oral polio vaccine, Quinvaxem, and measles 1 vaccine significantly increased over time from baseline to post-intervention to one year post-intervention. In particular, the timeliness of vaccination with the third dose of Quinvaxem increased from 53.6% to 65.8% to 77.2%. For measles 1 vaccine, the rate increased from 70.4% to 76.2% to 92.3%. In addition, the dropout rate from Quinvaxem 1 to Quinvaxem 3 declined from 4.2% in 2013 to 0% in 2015, and the dropout rate from Bacillus Calmette-Guérin (BCG) to measles 1 fell from 12.8% in 2013 to 0% in 2015. Full immunization coverage of children under one year old increased significantly from 75.4% in 2013 to 81.7% in 2014 to 99.2% in 2015. Also, survey results indicated that 93.3% of interviewees were willing to pay for SMS reminders for immunization. A digital immunization registry that includes SMS reminders can improve immunization coverage and timeliness of vaccination, thereby strengthening the quality and effectiveness of immunization programs. Integrating this system into the national health information system and leveraging it for other health programs, such as maternal and child health and nutrition as well as infectious disease control, can bring more benefits to the health care system in Vietnam.

Reaching the unreached with polio vaccine and other child survival interventions through partnership with military in Angola

BackgroundGrowing conflict and insecurity played a major role in precipitating polio outbreaks in the Horn of Africa and the Middle East. In Angola, the early post-conflict situation was characterized by the presence of many inaccessible zones and districts due to insecurity and poor infrastructure. Partnership with the Angolan Army health service (AAHS) was one of the innovative strategies that the Polio Eradication Initiative (PEI) introduced into the country to support the polio vaccination campaigns in insecure and hard to reach zones. MethodsBefore embarking on creating a partnership with Angolan military it was essential to make high-level advocacy with top military decision makers to engage the leadership in the process for better and sustainable support to the strategy. The principal supports provided by the AAHS were the administration of oral polio vaccine, vitamin A, deworming agents, social mobilization, monitoring campaign quality, and surveillance. Distribution of logistics using military vehicles and helicopters to hard to reach and insecure zones was also part of the support. ResultsUsing this partnership it was possible to reach a significant number of children in insecure and hard to reach areas with polio vaccine and other child survival interventions. The military partnership also contributed in increasing the demand and addressing rejection for the polio vaccine. ConclusionMilitary is a potentially productive force that can be used for any development activities in any country. The Angolan experience has demonstrated that it is possible to form a partnership with the military for basic health intervention activities with little training and investment.

Effect of simultaneous administration of oral polio vaccine on local reaction of BCG vaccine in term infants.

To study local reaction and to ascertain timing of scar formation in infants after BCG vaccination at birth, with and without simultaneous administration of trivalent OPV. Prospective observational study. Teaching hospital in Lucknow, India. 152 term neonates born in the hospital and given BCG and OPV 0-dose simultaneously before discharge, within 7 days of birth (Group I) , and 122 infants born at home or in private health facility, not given OPV-0 dose, coming for vaccination within 7 days of age (Group 2). Follow up done at 6 week, 10 week, 14 week and 9 months. Local reaction was recorded at the site of BCG vaccination. Scar formed in ≤14 wks in 51.3% and 89.3% babies in Group 1 and Group 2, respectively following BCG vaccination (P<0.001). At 9 months, scar developed in 93.9% infants in Group I and 94.3% babies in Group II. Abortive reaction and non-reactors were similar in both groups (P>0.05). Simultaneous administration of BCG vaccine with trivalent OPV to term infants in early neonatal period prolongs the time of scar formation but sequence of local reaction is not affected.

Vaccine schedule compliance among very low birth weight infants in Lima, Peru

ObjectiveThere is little information about vaccine schedule compliance in very-low-birth-weight infants in developing countries. The aim of the study was to describe the compliance with the vaccine schedule among this population in Lima, Peru. Patients and methodsWe conducted a prospective cohort study in four hospitals in Lima in infants with a birth-weight of less than 1500g, followed from birth up to 12 months of age every 2 weeks. The date and age at administration of each vaccine was recorded Results222 infants were enrolled. The median birth-weight was 1250g (range 550–1499g) and the median gestational age was 30.0 weeks (range 23–37 weeks). The mean age for the first pentavalent (DPT, Hib, HepB) and oral polio vaccine administration was 4.3±1.4 months in infants with a birth-weight of <1000g vs. 3.1±1.0 in infants with a birth-weight 1000–1500g (p<0.001); 4.1±0.9 vs. 3.3±1.1 for rotavirus (p<0.05); and 5.1±2.1 vs. 4.3±1.8 for the 7-valent pneumococcal conjugated vaccine. Only 35% had received the three doses of oral polio and pentavalent vaccine by seven months, although by nine months 81% had received these vaccines. ConclusionsVaccination of very-low-birth-weight infants in Peru is significantly delayed, especially in infants with a birth-weight of <1000g and lower gestational age. Urgent educational interventions targeting physicians and nurses should be implemented in order to improve vaccination rates and timing in these high risk populations.

Kinetics of poliovirus shedding following oral vaccination as measured by quantitative reverse transcription-PCR versus culture.

Amid polio eradication efforts, detection of oral polio vaccine (OPV) virus in stool samples can provide information about rates of mucosal immunity and allow estimation of the poliovirus reservoir. We developed a multiplex one-step quantitative reverse transcription-PCR (qRT-PCR) assay for detection of OPV Sabin strains 1, 2, and 3 directly in stool samples with an external control to normalize samples for viral quantity and compared its performance with that of viral culture. We applied the assay to samples from infants in Dhaka, Bangladesh, after the administration of trivalent OPV (tOPV) at weeks 14 and 52 of life (on days 0 [pre-OPV], +4, +11, +18, and +25 relative to vaccination). When 1,350 stool samples were tested, the sensitivity and specificity of the quantitative PCR (qPCR) assay were 89 and 91% compared with culture. A quantitative relationship between culture(+)/qPCR(+) and culture(-)/qPCR(+) stool samples was observed. The kinetics of shedding revealed by qPCR and culture were similar. qPCR quantitative cutoffs based on the day +11 or +18 stool samples could be used to identify the culture-positive shedders, as well as the long-duration or high-frequency shedders. Interestingly, qPCR revealed that a small minority (7%) of infants contributed the vast majority (93 to 100%) of the total estimated viral excretion across all subtypes at each time point. This qPCR assay for OPV can simply and quantitatively detect all three Sabin strains directly in stool samples to approximate shedding both qualitatively and quantitatively.

Moderate preterm children have more respiratory problems during their first five years of life than children born full term

There is little information about vaccine schedule compliance in very-low-birth-weight infants in developing countries. The aim of the study was to describe the compliance with the vaccine schedule among this population in Lima, Peru.We conducted a prospective cohort study in four hospitals in Lima in infants with a birth-weight of less than 1500 g, followed from birth up to 12 months of age every 2 weeks. The date and age at administration of each vaccine was recorded222 infants were enrolled. The median birth-weight was 1250 g (range 550–1499 g) and the median gestational age was 30.0 weeks (range 23–37 weeks). The mean age for the first pentavalent (DPT, Hib, HepB) and oral polio vaccine administration was 4.3 ± 1.4 months in infants with a birth-weight of <1000 g vs. 3.1 ± 1.0 in infants with a birth-weight 1000–1500 g (p < 0.001); 4.1 ± 0.9 vs. 3.3 ± 1.1 for rotavirus (p < 0.05); and 5.1 ± 2.1 vs. 4.3 ± 1.8 for the 7-valent pneumococcal conjugated vaccine. Only 35% had received the three doses of oral polio and pentavalent vaccine by seven months, although by nine months 81% had received these vaccines.Vaccination of very-low-birth-weight infants in Peru is significantly delayed, especially in infants with a birth-weight of <1000 g and lower gestational age. Urgent educational interventions targeting physicians and nurses should be implemented in order to improve vaccination rates and timing in these high risk populations.

Paralytic Poliomyelitis Associated With Sabin Monovalent and Bivalent Oral Polio Vaccines in Hungary

Historical records of patients with vaccine-associated paralytic poliomyelitis (VAPP) in Hungary during 1961-1981 were reviewed to assess the risk of VAPP after oral polio vaccine (OPV) administration. A confirmed VAPP case was defined as a diagnosis of paralytic poliomyelitis and residual paralysis at 60 days in a patient with an epidemiologic link to the vaccine. Archived poliovirus isolates were retested using polymerase chain reaction and sequencing of the viral protein 1 capsid region. This review confirmed 46 of 47 cases previously reported as VAPP. Three cases originally linked to monovalent OPV (mOPV) 3 and one case linked to mOPV1 presented after administration of bivalent OPV 1 + 3 (bOPV). The adjusted VAPP risk per million doses administered was 0.18 for mOPV1 (2 cases/11.13 million doses), 2.96 for mOPV3 (32 cases/10.81 million doses), and 12.82 for bOPV (5 cases/390,000 doses). Absence of protection from immunization with inactivated poliovirus vaccine or exposure to OPV virus from routine immunization and recent injections could explain the higher relative risk of VAPP in Hungarian children. In polio-endemic areas in which mOPV3 and bOPV are needed to achieve eradication, the higher risk of VAPP would be offset by the high risk of paralysis due to wild poliovirus and higher per-dose efficacy of mOPV3 and bOPV compared with trivalent OPV.

HIV-infected children vaccination coverage and safety in a Western European cohort: a retrospective study

Since the implementation of highly active antiretroviral therapy in HIV-infected children, response to scheduled vaccines may determinate future morbidity and mortality. The aims of this study have been to describe the current vaccine coverage, vaccine safety and concordance with vaccine recommendations of the 68 HIV-infected children and adolescents followed up in our Unit. Forty-four percent of the children received at least one dose of the oral polio vaccine (OPV). Only 9.1% needed and received a second set of hepatitis B virus immunization because of low vaccine response. Only 14.7% were vaccinated against varicella. Coverages of 82.3% and 100% have been reached with the 23-valent and the 7-valent pneumococcal vaccines, respectively. Meningococcal conjugated vaccine uptake was moderate (80.8%). Influenza annual vaccination coverage was poor: only 22.7% had well-documented yearly vaccines. In our experience, vaccine coverage is lower in those vaccines administered in primary care centres compared with the immunizations given at the hospital. OPV administration did not cause any adverse effect in the children or in their families. Vaccine coverage in HIV-infected children was suboptimal.

Vaccine-associated Paralytic Poliomyelitis : A Case Report of Flaccid Monoparesis after Oral Polio Vaccine

This report describes a case of acute flaccid paralysis after administration of oral polio vaccine (OPV). A 4 month-old male patient with the decreased movement of left lower extremity for 1 month was transferred to the Department of Pediatrics. He received OPV with DTaP at 2 months of age. Flaccid paralysis was detected 4 weeks after OPV immunization. Attempts to isolate Sabin-like viruses in the two stool and CSF samples failed because those specimens were collected more than 2 month after the onset of paralysis. Hypotonic monoparesis (GIV/V), hypotonia and atrophy on the left lower extremity, and ipsilateral claw foot persisted for more than 18 months, while we followed him with rehabilitation therapy. This is the first case of officially approved, recipient vaccine-associated paralytic poliomyelitis in Korea.

Does the concurrent administration of an inactivated hepatitis A vaccine influence the immune response to other travelers vaccines?

Travelers seeking protection from hepatitis A also often need protection against other infections, prevalent at their destinations. A total of 396 volunteers received not only a hepatitis A vaccine but also either a vaccine against polio, hepatitis B, diphtheria, tetanus, yellow fever, Japanese encephalitis, typhoid fever or rabies according to their individual needs. We investigated the potential influence of the hepatitis A vaccination on the immune response to the other travelers vaccines that were administered concurrently. With seroprotection rates of 100% for yellow fever, Japanese encephalitis and rabies immunization and tetanus boosters our data demonstrate that the concurrent administration of hepatitis A vaccine does not compromise the immune response of these vaccines. Also for oral typhoid, hepatitis B and diphtheria vaccination we did not detect a negative influence of concurrent hepatitis A vaccine administration as compared with respective vaccinations when given alone. Prior to vaccination, more than one third of our subjects lacked protective antibody levels against diphtheria and only 44% of initially seronegative travelers seroconverted to an anti-diphtheria titer > or = 0.01 mIU/mL, supporting a need for an additional dose. Furthermore, only two thirds of the vaccinees tested prior to vaccination were protected against polio type 3, and the seroconversion rate following the administration of oral polio vaccine, was lower for viral type 3 (80%), as has been previously demonstrated in settings without concurrent other vaccinations. No negative effect of concurrent travelers vaccinations on the immune response of a hepatitis A vaccine has been detected in a previous report, and, likewise our data suggest no impairment of the antibody response of these travelers vaccines by the concurrent administration of the hepatitis A vaccine.

Assessment of vaccine wastage during a pulse polio immunization programme in India.

A study to assess the wastage factor of oral polio vaccine (OPV) in the Pulse Polio Immunization (PPI) programme of the Government of India was undertaken by the Indian Council of Medical Research (ICMR) at approximately 31,000 immunization booths all over the country. The study was conducted through the network of 31 Human Reproduction Research Centres (HRRCs) and other ICMR institutes. Wastage at the point of administration of OPV was estimated to be 14.5% with a wastage factor of 1.17 which is well below the assumed wastage of 33% and the corresponding wastage factor of 1.5 in the PPI programme. The wastage and wastage factor as estimated in the present study were also less than the wastage of 25% and the wastage factor of 1.33 recommended by the World Health Organization. Minimum wastage (6.3%) at Kanchipuram and maximum wastage (22.1%) at Kanpur were observed. Further, the wastage of unopened vials and vials during use was also observed following colour changes on the vaccine vial monitor (VVM), indicating poor cold-chain maintenance at the immunization site. In total, 13 booths reported wastage of nine or more unopened vials, whereas 19 booths reported wastage of nine or more vials during use because of colour changes on VVM. Other reasons for wastage of vaccine were also observed from a sample of booths. The technology of introducing VVM on OPV vials for monitoring the cold-chain proved useful in situations in which mass vaccination programmes such as PPI are carried out.

Polio eradication: the OPV paradox.

Routine and mass administration of oral polio vaccine (OPV) since 1961 has prevented many millions of cases of paralytic poliomyelitis. The public health value of this inexpensive and easily administered product has been extraordinary. Progress of the Global Polio Eradication Initiative has further defined the value of OPV as well as its risk through vaccine-associated paralytic poliomyelitis (VAPP) and vaccine-derived polioviruses (VDPV). Although both are rare, once wild poliovirus transmission has been interrupted by OPV, the only poliomyelitis due to poliovirus will be caused by OPV. Poliovirus will be eradicated only when OPV use is discontinued. This paradox provides a major incentive for eventually stopping polio immunization or replacing OPV, but it also introduces complexity into the process of identifying safe and scientifically sound strategies for doing so. The core post eradication immunization issues include the risk/benefits of continued OPV use, the extent of OPV replacement with IPV, possible strategies for discontinuing OPV, and the potential for development and licensure of a safe and effective replacement for OPV. Formulation of an informed post eradication immunization policy requires careful evaluation of polio epidemiology, surveillance capability, vaccine availability, laboratory containment, and the risks posed by the very tool responsible for successful interruption of wild poliovirus transmission.

Excretion of wild-type and vaccine-derived poliovirus in the feces of poliovirus receptor-transgenic mice.

The emergence of circulating vaccine-derived poliovirus (cVDPV) strains in suboptimally vaccinated populations is a serious threat to the global poliovirus eradication. The genetic determinants for the transmissibility phenotype of polioviruses, and in particularly of cVDPV strains, are currently unknown. Here we describe the fecal excretion of wild-type poliovirus, oral polio vaccine, and cVDPV (Hispaniola) strains after intraperitoneal injection in poliovirus receptor-transgenic mice. Both the pattern and the level of fecal excretion of the cVDPV strains resemble those of wild-type poliovirus type 1. In contrast, very little poliovirus was present in the feces after oral polio vaccine administration. This mouse model will be helpful in elucidating the genetic determinants for the high fecal-oral transmission phenotype of cVDPV strains.

Vaccine-associated paralytic poliomyelitis in India during 1999: decreased risk despite massive use of oral polio vaccine.

Vaccine-associated paralytic poliomyelitis (VAPP) is a rare but serious consequence of the administration of oral polio vaccine (OPV). Intensified OPV administration has reduced wild poliovirus transmission in India but VAPP is becoming a matter of concern. We analysed acute flaccid paralysis (AFP) surveillance data in order to estimate the VAPP risk in this country. VAPP was defined as occurring in AFP cases with onset of paralysis in 1999, residual weakness 60 days after onset, and isolation of vaccine-related poliovirus. Recipient VAPP cases were a subset with onset of paralysis between 4 and 40 days after receipt of OPV. A total of 181 AFP cases met the case definition. The following estimates of VAPP risk were made: overall risk, 1 case per 4.1 to 4.6 million OPV doses administered; recipient risk,1 case per 12.2 million; first-dose recipient risk, 1 case per 2.8 million; and subsequent-dose recipient risk, 1 case per 13.9 million. On the basis of data from a highly sensitive surveillance system the estimated VAPP risk in India is evidently lower than that in other countries, notwithstanding the administration of multiple OPV doses to children in mass immunization campaigns.

An epidemiologic, clinical, and therapeutic study of childhood Guillain-Barré syndrome in Kuwait: is it related to the oral polio vaccine?

We studied Guillain-Barré syndrome, affecting children 12 years old or less, throughout Kuwait, in the period between January 1, 1992, and March 31, 1997. Nineteen children had the diagnostic criteria of Guillain-Barré syndrome, with an overall annual incidence rate of 0.95/100,000 population at risk. Female patients outnumbered male patients with a sex ratio of 1.4:1. There was a clustering of cases in winter and spring and in the year 1996. The disease symptoms were relatively severe in our patients because only 16% (3 of 19) of them were able to walk at the height of their illness, whereas the rest were bed or chair bound or needed assisted ventilation. Two patients had the electrodiagnostic features of axonal neuropathy and both had residual deficits on follow-up, whereas the rest recovered fully. All the patients received intravenous immunoglobulin. The mean time to walk unaided was 23.5 days (range, 2-84 days) after intravenous immunoglobulin and excluding the two patients with axonal neuropathy, and full recovery was achieved in a mean time of 103 days (range, 30-300 days). Contrary to previous studies, we found no correlation between oral polio vaccine administration and Guillain-Barré syndrome in 2 successive years (1995 and 1996) during a nationwide campaign targeting children less than 5 years old.