Inactivated Polio Vaccine Research Articles

Alternative delivery of a thermostable inactivated polio vaccine

In the near future oral polio vaccine (OPV) will be replaced by inactivated polio vaccine (IPV) as part of the eradication program of polio. For that reason, there is a need for substantial amount of safe and more affordable IPV for low-income countries. Bioneedles, which are biodegradable mini-implants, have the potential to deliver vaccines outside the cold-chain and administer them without the use of needles and syringes. In the current study, Bioneedles were filled with IPV, subsequently lyophilized, and antigenic recoveries were determined both directly after IPV-Bioneedle preparation as well as after elevated stability testing. Further, we assessed the immunogenicity of IPV-Bioneedles in rats and the residence time at the site of administration.Trivalent IPV was formulated in Bioneedles with recoveries of 101±10%, 113±18%, and 92±15%, respectively for serotypes 1, 2 and 3. IPV in Bioneedles is more resistant to elevated temperatures than liquid IPV: liquid IPV retained less than half of its antigenicity after 1 day at 45°C and IPV in Bioneedles showed remaining recoveries of 80±10%, 85±4% and 63±4% for the three serotypes. In vivo imaging revealed that IPV administered via Bioneedles as well as subcutaneously injected liquid IPV showed a retention time of 3 days at the site of administration. Finally, an immunogenicity study showed that IPV-filled Bioneedles are able to induce virus-neutralizing antibody titers similar to those obtained by liquid intramuscular injection when administered in a booster regime. The addition of LPS-derivate PagL in IPV-filled Bioneedles did not increase immunogenicity compared to IPV-Bioneedles without adjuvant.The current study demonstrates the pre-clinical proof of concept of IPV-filled Bioneedles as a syringe-free alternative delivery system. Further pre-clinical and clinical studies will be required to assess the feasibility whether IPV-Bioneedles show sufficient safety and efficacy, and may contribute to the efforts to eradicate and prevent polio in the future.

Field study of fecal excretion as a decision support tool in response to silent reintroduction of wild-type poliovirus 1 into Israel

BackgroundIsrael has used an inactivated polio vaccine (IPV)-only schedule since 2005 (95% coverage). Silent reintroduction of wild type poliovirus 1 (WPV1) into Israel in early 2013 was detected in Southern Israel via routine environmental surveillance without clinical cases. ObjectivesTo estimate the rate of WPV1 excretion by age and residence and inform decision-making regarding supplemental immunization with OPV. Study designA convenience sample of Bedouin and Jewish residential areas in the epicenter of the incident, focusing on under 8 year-olds who not previously given OPV. Fecal samples were directly tested for WPV1 RNA using a novel qRT-PCR assay. Positive samples were confirmed by gold standard cell culture and subject to genotyping. ResultsOverall, 2196 non-duplicate fecal samples were collected and analyzed. WPV1 was detected in 61 samples (2.8%), 55 of which (90.2%) were from Bedouins. WPV1 excretion rates were 5.4% among Bedouins and 0.6% among Jewish individuals. Respective age-specific rates among Bedouin and Jewish children were 4.9% and 0.2% for 0–2 years and 7.2% and 1.7% for 2–8 years. Molecular testing had 89.5% sensitivity (higher than culture) and 100% specificity. ConclusionThe rapid performance of a field study to evaluate WPV1 excretion unequivocally demonstrated substantial WPV1 infection rates among children under 8 years in Southern Israel, thus informing the decision to vaccinate this age group with bOPV and risk communication to both healthcare personnel and the public. Rapid development and implementation of molecular screening can thus underpin risk assessment and management in complex epidemiological situations.

The novel adjuvant dmLT promotes dose sparing, mucosal immunity and longevity of antibody responses to the inactivated polio vaccine in a murine model

One option for achieving global polio eradication is to replace the oral poliovirus vaccine (OPV), which has the risk of reversion to wild-type virulence, with the inactivated poliovirus vaccine (IPV) vaccine. Adjuvants and alternate routes of immunization are promising options that may reduce antigen dose in IPV vaccinations, potentially allowing dose sparing and cost savings. Use of adjuvants and alternate routes of immunization could also help promote mucosal immunity, potentially mimicking the protection against intestinal virus shedding seen with OPV. In the current study, we examined the impact of combining the novel adjuvant dmLT with trivalent IPV for dose sparing, induction of mucosal immunity and increasing longevity of anti-poliovirus (PV) responses in a mouse model following either intradermal (ID) or intramuscular (IM) delivery.We found that non-adjuvanted ID delivery was not superior to IM delivery for fractional dose sparing, but was associated with development of mucosal immunity. Vaccination with IPV+dmLT promoted serum anti-PV neutralizing antibodies with fractional IPV doses by either IM or ID delivery, achieving at least five-fold dose sparing above non-adjuvanted fractional doses. These responses were most noticeable with the PV1 component of the trivalent vaccine. dmLT also promoted germinal center formation and longevity of serum anti-PV neutralizing titers. Lastly, dmLT enhanced mucosal immunity, as defined by fecal and intestinal anti-PV IgA secretion, when included in IPV immunization by ID or IM delivery. These studies demonstrate that dmLT is an effective adjuvant for either IM or ID delivery of IPV. Inclusion of dmLT in IPV immunizations allows antigen dose sparing and enhances mucosal immunity and longevity of anti-PV responses.

Inactivated polio vaccination using a microneedle patch is immunogenic in the rhesus macaque

The phased replacement of oral polio vaccine (OPV) with inactivated polio vaccine (IPV) is expected to significantly complicate mass vaccination campaigns, which are an important component of the global polio eradication endgame strategy. To simplify mass vaccination with IPV, we developed microneedle patches that are easy to administer, have a small package size, generate no sharps waste and are inexpensive to manufacture. When administered to rhesus macaques, neutralizing antibody titers were equivalent among monkeys vaccinated using microneedle patches and conventional intramuscular injection for IPV types 1 and 2. Serologic response to IPV type 3 vaccination was weaker after microneedle patch vaccination compared to intramuscular injection; however, we suspect the administered type 3 dose was lower due to a flawed pre-production IPV type 3 analytical method. IPV vaccination using microneedle patches was well tolerated by the monkeys. We conclude that IPV vaccination using a microneedle patch is immunogenic in rhesus macaques and may offer a simpler method of IPV vaccination of people to facilitate polio eradication.

Immunogenicity and persistence from different 3-dose schedules of live and inactivated polio vaccines in Chinese infants

BackgroundOPV is the only poliovirus vaccine used in the China EPI system, although IPV is available in the private market. We compared immunigencity and persistence among different schedules of IPV and OPV. Methods536 Chinese infants were enrolled into 4 groups receiving different schedules administered at 2, 3, and 4 months of age: IPV–OPV–OPV, IPV–IPV–OPV, IPV–IPV–IPV, and OPV–OPV–OPV. The I–I–I group received an 18-month IPV booster dose. Blood samples were collected before the first dose, after the third dose, and at 18 months for all groups, and also after the booster dose for the I–I–I group. Polio neutralizing antibody titers were assessed, and seroprotection rates were calculated after primary immunization and at 18 months of age. ResultsBefore the first dose, GMTs of the 4 groups ranged from 2.96 to 6.89, and seroprotection rates ranged from 17.6% to 54.3%. After 3 doses, the GMT of the I–O–O and I–I–O groups ranged from 901.09 to 1,110.12, and the GMT of the I–I–I group range was 212.02 to 537.52, significantly lower than for the 2 sequential schedules (P<0.001). Seroprotection rates were 98.1% to 100%, with no significant differences among groups. At 18 months of age, the GMTs declined to a range of 527.00 to 683.44 in the I–O–O and I–I–O groups, and declined to 150.04 to 239.89 in the I–I–I group, significantly lower than for the other 3 groups (P<0.001). ConclusionsThe sequential schedules achieved high GMTs and seroprotection. The IPV-only schedule achieved high seroprotection but with lower GMTs. Sequential schedules are suitable for China. With the 2 sequential schedules, GMTs remained high at 18 months of age and were not inferior to the OPV-only schedule. Thus, with a sequential schedule, the booster dose could be given at 4 years of age, the same age as the current OPV booster dose.

Environmental surveillance of poliovirus in sewage water around the introduction period for inactivated polio vaccine in Japan.

Environmental virus surveillance was conducted at two independent sewage plants from urban and rural areas in the northern prefecture of the Kyushu district, Japan, to trace polioviruses (PVs) within communities. Consequently, 83 PVs were isolated over a 34-month period from April 2010 to January 2013. The frequency of PV isolation at the urban plant was 1.5 times higher than that at the rural plant. Molecular sequence analysis of the viral VP1 gene identified all three serotypes among the PV isolates, with the most prevalent serotype being type 2 (46%). Nearly all poliovirus isolates exhibited more than one nucleotide mutation from the Sabin vaccine strains. During this study, inactivated poliovirus vaccine (IPV) was introduced for routine immunization on 1 September 2012, replacing the live oral poliovirus vaccine (OPV). Interestingly, the frequency of PV isolation from sewage waters declined before OPV cessation at both sites. Our study highlights the importance of environmental surveillance for the detection of the excretion of PVs from an OPV-immunized population in a highly sensitive manner, during the OPV-to-IPV transition period.

Polio inactivated vaccine costs into routine childhood immunization in Brazil.

OBJECTIVE To analyze the costs of vaccination regimens for introducing inactivated polio vaccine in routine immunization in Brazil.METHODS A cost analysis was conducted for vaccines in five vaccination regimens, including inactivated polio vaccine, compared with the oral polio vaccine-only regimen. The costs of the vaccines were estimated for routine use and for the “National Immunization Days”, during when the oral polio vaccine is administered to children aged less than five years, independent of their vaccine status, and the strategic stock of inactivated polio vaccine. The presented estimated costs are of 2011.RESULTS The annual costs of the oral vaccine-only program (routine and two National Immunization Days) were estimated at US$19,873,170. The incremental costs of inclusion of the inactivated vaccine depended on the number of vaccine doses, presentation of the vaccine (bottles with single dose or ten doses), and number of “National Immunization Days” carried out. The cost of the regimen adopted with two doses of inactivated vaccine followed by three doses of oral vaccine and one “National Immunization Day” was estimated at US$29,653,539. The concomitant replacement of the DTPw/Hib and HepB vaccines with the pentavalent vaccine enabled the introduction of the inactivated polio without increasing the number of injections or number of visits needed to complete the vaccination.CONCLUSIONS The introduction of the inactivated vaccine increased the annual costs of the polio vaccines by 49.2% compared with the oral vaccine-only regimen. This increase represented 1.13% of the expenditure of the National Immunization Program on the purchase of vaccines in 2011.

Looking Back and Planning Ahead: Examining Global Best Practices in Communication for Inactivated Polio Vaccination Introduction in Rwanda

The global polio community is committed to ensuring that all countries currently using oral polio vaccination (OPV) add at least one dose of inactivated polio vaccination (IPV) to their immunization schedules. Globally, communication efforts have been at the forefront of polio eradication programs for more than 25 years. This article combines research from secondary and primary sources of information on country experiences in polio vaccination and from the polio vaccination program in Rwanda. Secondary data included a review of 20 global articles that describe and analyze communication efforts for polio eradication and highlight best practices in communication approaches to address polio. The primary research consisted of qualitative and participatory data gathered from various stakeholders in two rural sites in Rwanda regarding approaches that could be used to develop culturally sound communication strategies to introduce IPV into the current routine expanded program on immunization schedule. Findings fr...

Introduction of Inactivated Polio Vaccine and Specific Determinants of Vaccine Hesitancy

Background: Introduction of inactivated polio vaccine is imminent and may encounter the challenges that face new vaccines especially vaccine hesitancy. The study evaluated factors that may contribute to hesitancy towards IPV. Methods: Questionnaire adapted from the model developed by the Strategic Advisory Group of Experts Working Group (SAGE WG) was used to assess the factors among 408 parents. The evaluation was under the 3 Cs: Confidence, Complacency and Convenience. Questions were scored on Likert 4-unit-scale system. The data were analyzed using SPSS and, multivariate analysis was used to further test individual significant variables. Results: Overall, Complacency (2.29) and Convenience (2.11) domains were more pro-vaccine hesitant, than Confidence (1.83) domain. However, none was significantly associated with likelihood of a parent’s hesitancy towards IPV vaccination. But certain individual questions: competence of vaccinators (p = 0.04), confidence that their child will not to be infected with poliomyelitis even when not vaccinated (p = 0.03) and, willingness to vaccinate with IPV when OPV is still in use (p = 0.01) were significantly associated with vaccine hesitancy. Conclusions: None of the factors can individually influence acceptance of IPV. However, competence of vaccinators, parental belief and availability of close alternative influenced parental decision to vaccinate.

Genetic analysis and characterization of wild poliovirus type 1 during sustained transmission in a population with >95% vaccine coverage, Israel 2013.

Israel has >95% polio vaccine coverage with the last 9 birth cohorts immunized exclusively with inactivated polio vaccine (IPV). Using acute flaccid paralysis and routine, monthly countrywide environmental surveillance, no wild poliovirus circulation was detected between 1989 and February 2013, after which wild type 1 polioviruses South Asia genotype (WPV1-SOAS) have persistently circulated in southern Israel and intermittently in other areas without any paralytic cases as determined by intensified surveillance of environmental and human samples. We aimed to characterize antigenic and neurovirulence properties of WPV1-SOAS silently circulating in a highly vaccinated population. WPV1-SOAS capsid genes from environmental and stool surveillance isolates were sequenced, their neurovirulence was determined using transgenic mouse expressing the human poliovirus receptor (Tg21-PVR) mice, and their antigenicity was characterized by in vitro neutralization using human sera, epitope-specific monoclonal murine anti-oral poliovirus vaccine (OPV) antibodies, and sera from IPV-immunized rats and mice. WPV1 amino acid sequences in neutralizing epitopes varied from Sabin 1 and Mahoney, with little variation among WPV1 isolates. Neutralization by monoclonal antibodies against 3 of 4 OPV epitopes was lost. Three-fold lower geometric mean titers (Z = -4.018; P < .001, Wilcoxon signed-rank test) against WPV1 than against Mahoney in human serum correlated with 4- to 6-fold lower neutralization titers in serum from IPV-immunized rats and mice. WPV1-SOAS isolates were neurovirulent (50% intramuscular paralytic dose in Tg21-PVR mice: log10(7.0)). IPV-immunized mice were protected against WPV1-induced paralysis. Phenotypic and antigenic profile changes of WPV1-SOAS may have contributed to the intense silent transmission, whereas the reduced neurovirulence may have contributed to the absence of paralytic cases in the background of high population immunity.

Emerging Problems Impeding the Elimination of the Last Polioviruses: Silent Circulation of Wild Strains in a Well-Immunized Population

Despite high polio vaccine coverage, Israel recently experienced a silent surge in the transmission ofwild poliovirus inthe population. In this issue of Clinical Infectious Diseases, Shulman and colleagues report interesting data about the antigenic and pathogenic features of the poliovirus strain circulating in that country. Poliovirus, the causative agent of poliomyelitis, replicates mainly in the tonsils and in the small intestine. It is most often transmitted by the fecal–oral route and is extremely contagious. In most cases, replication of the virus in infected people remains asymptomatic or gives rise to only mild symptoms [1]. Paralytic poliomyelitis is relatively rare, affecting between 1 in 200 and 1 in 2000 infected people depending on the serotype of the virus (1, 2, and 3). Two vaccines effectively prevent poliomyelitis. The inactivated injectable polio vaccine (IPV) was developed by Jonas Salk through the chemical inactivation of neurovirulent strains of the 3 serotypes; it is very safe and induces a strong and protective general antibody response. The live attenuated oral polio vaccine (OPV) was developed by Albert Sabin and induces a long-term protective response; this response includes an effective intestinal immunity that restricts interhuman circulation and replication of the virus. However, a problematic aspect of OPV is a consequence of the genetic instability of the 3 attenuated strains (Sabin 1–3). Multiplication of OPV strains in vaccinees allows their genetic drift and loss of attenuation. Consequently, neurovirulent

Post-polio eradication: vaccination strategies and options for India

In 1988, the World Health Organization (WHO) resolved to eradicate poliomyelitis globally. Since then, the initiative has reported dramatic progress in decreasing the incidence of poliomyelitis and limiting the geographical extent of transmission. 2013 is recorded as the second consecutive year not reporting wild poliovirus (WPV) from India. If the country can retain this position for one more year India will be declared as polio eradicated. What should be the future vaccination strategies? We searched and reviewed the full text of the available published literature on polio eradication via PubMed and examined Internet sources and websites of major international health agencies. The oral polio vaccine (OPV) has been the main tool in the polio eradication program. Once WPV transmission is interrupted, the poliomyelitis will be caused only by OPV. India could expect 1 vaccine-associated paralytic polio per 4.2-4.6 million doses of OPV. Considering the threat of vaccine-derived viruses to polio eradication, WHO urged to develop a strategy to safely discontinue OPV after certification. The ultimate aim is to stop OPV safely and effectively, and eventually substitute with inactivated polio vaccine (IPV). The argument against the use of IPV is its cost. From India, field based data were available on the efficacy of IPV, which was better than OPV. IPV given intradermally resulted in seroconversion rates similar to full-dose intramuscular vaccine. The incremental cost of adopting IPV to replace OPV is relatively low, about US $1 per child per year, and most countries should be able to afford this additional cost.

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Serum and mucosal antibody responses to inactivated polio vaccine after sublingual immunization using a thermoresponsive gel delivery system

Administering vaccines directly to mucosal surfaces can induce both serum and mucosal immune responses. Mucosal responses may prevent establishment of initial infection at the port of entry and subsequent dissemination to other sites. The sublingual route is attractive for mucosal vaccination, but both a safe, potent adjuvant and a novel formulation are needed to achieve an adequate immune response. We report the use of a thermoresponsive gel (TRG) combined with a double mutant of a bacterial heat-labile toxin (dmLT) for sublingual immunization with a trivalent inactivated poliovirus vaccine (IPV) in mice. This TRG delivery system, which changes from aqueous solution to viscous gel upon contact with the mucosa at body temperature, helps to retain the formulation at the site of delivery and has functional adjuvant activity from the inclusion of dmLT. IPV was administered to mice either sublingually in the TRG delivery system or intramuscularly in phosphate-buffered saline. We measured poliovirus type-specific serum neutralizing antibodies as well as polio-specific serum Ig and IgA antibodies in serum, saliva, and fecal samples using enzyme-linked immunosorbent assays. Mice receiving sublingual vaccination via the TRG delivery system produced both mucosal and serum antibodies, including IgA. Intramuscularly immunized animals produced only serum neutralizing and binding Ig but no detectable IgA. This study provides proof of concept for sublingual immunization using the TRG delivery system, comprising a thermoresponsive gel and dmLT adjuvant.

Inactivated polio vaccine launch in Nepal: a public health milestone.

Inactivated polio vaccine launch in Nepal: a public health milestone.

Introduction of sequential inactivated polio vaccine-oral polio vaccine schedule for routine infant immunization in Brazil's National Immunization Program.

In August 2012, the Brazilian Ministry of Health introduced inactivated polio vaccine (IPV) as part of sequential polio vaccination schedule for all infants beginning their primary vaccination series. The revised childhood immunization schedule included 2 doses of IPV at 2 and 4 months of age followed by 2 doses of oral polio vaccine (OPV) at 6 and 15 months of age. One annual national polio immunization day was maintained to provide OPV to all children aged 6 to 59 months. The decision to introduce IPV was based on preventing rare cases of vaccine-associated paralytic polio, financially sustaining IPV introduction, ensuring equitable access to IPV, and preparing for future OPV cessation following global eradication. Introducing IPV during a national multivaccination campaign led to rapid uptake, despite challenges with local vaccine supply due to high wastage rates. Continuous monitoring is required to achieve high coverage with the sequential polio vaccine schedule.

Laboratory challenges in response to silent introduction and sustained transmission of wild poliovirus type 1 in Israel during 2013.

Wild poliovirus type 1 (WPV1) introduction into southern Israel in early 2013 was detected by routine environmental surveillance. The virus was identified genetically as related to the South Asian (SOAS) R3A lineage endemic to Pakistan in 2012. Intensified, high-throughput environmental surveillance using advanced molecular methods played a critical role in documenting and locating sustained transmission throughout 2013 and early 2014 in the absence of any acute flaccid paralysis. It guided the public health responses, including stool-based surveillance and serosurveys, to determine the point prevalence in silent excretors and measured the effect of vaccination campaigns with inactivated polio vaccine and bivalent oral polio vaccine on stopping transmission.

Strengthening the partnership between routine immunization and the global polio eradication initiative to achieve eradication and assure sustainability.

Since the launch of the Global Polio Eradication Initiative (GPEI) in 1988, the number of polio endemic countries has declined from 125 to 3 in 2013. Despite this remarkable achievement, ongoing circulation of wild poliovirus in polio-endemic countries and the increase in the number of circulating vaccine-derived poliovirus cases, especially those caused by type 2, is a cause for concern. The Polio Eradication and Endgame Strategic Plan 2013-2018 (PEESP) was developed and includes 4 objectives: detection and interruption of poliovirus transmission, containment and certification, legacy planning, and a renewed emphasis on strengthening routine immunization (RI) programs. This is critical for the phased withdrawal of oral poliovirus vaccine, beginning with the type 2 component, and the introduction of a single dose of inactivated polio vaccine into RI programs. This objective has inspired renewed consideration of how the GPEI and RI programs can mutually benefit one another, how the infrastructure from the GPEI can be used to strengthen RI, and how a strengthened RI can facilitate polio eradication. The PEESP is the first GPEI strategic plan that places strong and clear emphasis on the necessity of improving RI to achieve and sustain global polio eradication.

Mathematical model of adherent Vero cell growth and poliovirus production in animal component free medium.

Sabin-IPV (or sIPV, inactivated polio vaccine based on attenuated Sabin strains) is anticipated to replace the oral polio vaccine for the endgame in polio eradication. Optimization of sIPV production will lead to a better economically feasible vaccine. To assist process optimization, we studied Sabin type 1 poliovirus (PV) infection kinetics on Vero cells in controlled bioreactor vessels. The aim of our study was to develop a descriptive mathematical model able to capture the dynamics of adherent Vero cell growth and PV infection kinetics in animal component free medium. The model predicts the cell density, metabolites profiles, and viral yields in time. We found that the multiplicity of infection (MOI) and the time of infection (TOI) within the investigated range did not affect maximal PV yields, but they did affect the process time. The latter may be reduced by selecting a low TOI and a high MOI. Additionally, we present a correlation between viral titers and D-antigen, a measure for immunogenicity, of Sabin type 1 PV. The developed model is adequate for further studies of the cell metabolism and infection kinetics and may be used to identify control strategies to increase viral productivity. Increased viral yields reduce costs of polio vaccines with large implications on public health.

The budget impact of controlling wastage with smaller vials: A data driven model of session sizes in Bangladesh, India (Uttar Pradesh), Mozambique, and Uganda

IntroductionOpen vial vaccine wastage in multi-dose vials is a major contributor to vaccine wastage. Although switching from 10-dose vials to 5-dose vials could reduce wastage, a higher total cost could be triggered because smaller vials cost more to purchase and store. MethodsThis study drew field data of daily session sizes in local vaccination facilities from Bangladesh, India (Uttar Pradesh), Mozambique, and Uganda, and used Akaike Information Criteria to determine the best fit statistical distribution across various clinic types. These distributions were input to estimate the vaccine wastage using Lee's (2010) model. Inactivated polio vaccine (IPV) immunization was simulated to compare the costs over ten years with 10-dose vials versus 5-dose vials. ResultsBy switching from 10- to 5-dose vials, the observed open vial wastage rate due to vial size preference and session size for IPV was reduced from 0.25 to 0.11 in Bangladesh, 0.17 to 0.08 in India (Uttar Pradesh), 0.13 to 0.06 in Mozambique, and 0.09 to 0.04 in Uganda, respectively. The cost savings realized from lower IPV wastage did not offset the higher costs of procurement and storage costs associated with smaller dose presentation. ConclusionWhile our model showed that switching from 10-dose vials to 5-dose vials of IPV reduced open vial wastage, it was not cost-saving.