Polio endgame: the global introduction of inactivated polio vaccine

Safety and immunogenicity of shorter interval schedules of the novel oral poliovirus vaccine type 2 in infants: a phase 3, randomised, controlled, non-inferiority study in the Dominican Republic

BACKGROUND

The novel oral poliovirus vaccine type 2 (nOPV2) is now authorised by a WHO emergency use listing and widely distributed to interrupt outbreaks of circulating vaccine-derived poliovirus type 2. As protection of vulnerable populations, particularly young infants, could be facilitated by shorter intervals between the two recommended doses, we aimed to assess safety and non-inferiority of immunogenicity of nOPV2 in 1-week, 2-week, and 4-week schedules.

METHODS

In this phase 3, open-label, randomised trial, healthy, full-term, infants aged 6-8 weeks from a hospital or a clinic in the Dominican Republic were randomly allocated (1:1:1 ratio) using a pre-prepared, computer-generated randomisation schedule to three groups to receive two doses of nOPV2 immunisations with a 1-week interval (group A), 2-week interval (group B), or 4-week interval (group C). The nOPV2 vaccine was given at a 0·1 mL dose and contained at least 105 50% cell culture infective dose. Neutralising antibodies against poliovirus types 1, 2, and 3 were measured before each immunisation and 4 weeks after the second dose. The primary outcome was the type 2 seroconversion rate 28 days after the second dose, and the non-inferiority margin was defined as a lower bound 95% CI of greater than -10%. Safety and reactogenicity were assessed through diary cards completed by the parent or guardian. The trial is registered with ClinicalTrials.gov, NCT05033561.

FINDINGS

We enrolled 905 infants between Dec 16, 2021, and March 28, 2022. 872 infants were included in the per-protocol analyses: 289 in group A, 293 in group B, and 290 in group C. Type 2 seroconversion rates were 87·5% (95% CI 83·2 to 91·1) in group A (253 of 289 participants), 91·8% (88·1 to 94·7) in group B (269 of 293 participants), and 95·5% (92·5 to 97·6) in group C (277 of 290 participants). Non-inferiority was shown for group B compared with group C (difference in rates -3·7; 95% CI -7·9 to 0·3), but not for group A compared with group C (-8·0; -12·7 to -3·6). 4 weeks after the second nOPV2 dose, type 2 neutralising antibodies increased in all three groups such that over 95% of each group was seroprotected against polio type 2, although final geometric mean titres tended to be highest with longer intervals between doses. Immunisation with nOPV2 was well tolerated with no causal association to vaccination of any severe or serious adverse event; one death from septic shock during the study was unrelated to the vaccine.

INTERPRETATION

Two nOPV2 doses administered 1 week or 2 weeks apart from age 6 weeks to 8 weeks were safe and immunogenic. Immune responses after a 2-week interval were non-inferior to those after the standard 4-week interval, but marked responses after a 1-week interval suggest that schedules with an over 1-week interval can be used to provide flexibility to campaigns to improve coverage and hasten protection during circulating vaccine-derived poliovirus type 2 outbreaks.

FUNDING

Bill & Melinda Gates Foundation.

Oral and fecal polio vaccine excretion following bOPV vaccination among Israeli infants

INTRODUCTION

Inactivated polio virus (IPV) vaccinations are a mainstay of immunization schedules in developed countries, while oral polio vaccine (OPV) is administered in developing countries and is the main vaccine in outbreaks. Due to circulating wild poliovirus (WPV1) detection in Israel (2013), oral bivalent polio vaccination (bOPV) was administered to IPV primed children and incorporated into the vaccination regimen.

OBJECTIVES

We aimed to determine the extent and timeframe of fecal and salivary polio vaccine virus (Sabin strains) shedding following bOPV vaccination among IPV primed children.

METHODS

Fecal samples were collected from a convenience sample of infants and toddlers attending 11 Israeli daycare centers. Salivary samples were collected from infants and toddlers following bOPV vaccination.

RESULTS

398 fecal samples were collected from 251 children (ages: 6-32 months), 168 received bOPV vaccination 4-55 days prior to sample collection. Fecal excretion continued among 80 %, 50 %, and 20 %, 2, 3, and 7 weeks following vaccination. There were no significant differences in the rate and duration of positive samples among children immunized with 3 or 4 IPV doses. Boys were 2.3-fold more likely to excrete the virus (p = 0.006). Salivary shedding of Sabin strains occurred in 1/47 (2 %) and 1/49 (2 %) samples 4, and 6 days following vaccination respectively.

CONCLUSIONS

Fecal detection of Sabin strains among IPV-primed children continues for 7 weeks; additional doses of IPV do not augment intestinal immunity; limited salivary shedding occurs for up to a week. This data can enhance understanding of intestinal immunity achieved by different vaccination schedules and guide recommendations for contact precautions of children following bOPV vaccination.

Poliomyelitis is a current challenge: long-term sequelae and circulating vaccine-derived poliovirus

For more than 20 years, the World Health Organization Western Pacific Region (WPR) has been polio-free. However, two current challenges are still polio-related. First, around half of poliomyelitis elderly survivors suffer late poliomyelitis sequelae with a substantial impact on daily activities and quality of life, experiencing varying degrees of residual weakness as they age. The post-polio syndrome as well as accelerated aging may be involved. Second, after the worldwide Sabin oral poliovirus (OPV) vaccination, the recent reappearance of strains of vaccine-derived poliovirus (VDPV) circulating in the environment is worrisome and able to persistent person-to-person transmission. Such VDPV strains exhibit atypical genetic characteristics and reversed neurovirulence that can cause paralysis similarly to wild poliovirus, posing a significant obstacle to the elimination of polio. Immunization is essential for preventing paralysis in those who are exposed to the poliovirus. Stress the necessity of maintaining high vaccination rates because declining immunity increases the likelihood of reemergence. If mankind wants to eradicate polio in the near future, measures to raise immunization rates and living conditions in poorer nations are needed, along with strict observation. New oral polio vaccine candidates offer a promissory tool for this goal.

Safety, immunogenicity, and lot-to-lot consistency of a multidose Sabin strain-based inactivated polio vaccine: a phase III, randomized, blinded, positive-control clinical trial in infants aged 2 months

OBJECTIVES

To evaluate the safety, immunogenicity, and lot-to-lot consistency of Sabin strain-based inactivated polio vaccine (sIPV) in a five-dose vial presentation.

METHODS

Stage I was an open-label safety observation, in which 72 healthy subjects (including 24 adults, children, and infants each) were given one or three doses of the five-dose vial sIPV; stage II was a randomized, blinded, and positive-control study, in which 1500 infants were randomized at the ratio of 1: 1: 1: 1: 1 into five groups to receive either three doses of the five-dose sIPV three lots, a conventional inactivated poliovirus vaccine, or a single-dose sIPV as controls, for primary immunization. Safety, immunogenicity, and lot-to-lot consistency were assessed.

RESULTS

Among 1456 subjects who completed the primary immunization, the geometric mean titer ratios of types 1, 2, and 3 of each pair of lots were all within the equivalence criteria margin (0.67-1.50). The seroconversion rates of types 1, 2, and 3 in the combined test group were 98.02%, 94.07%, and 98.77%, respectively, which were noninferior to both control groups. The overall incidence of adverse reactions was 29.68% and erythema was the most common adverse reaction with incidences of 10.47%,9.33%, and 9.73% in the combined test group and control groups (P >0.05).

CONCLUSION

The five-dose sIPV demonstrated good safety, immunogenicity, and lot-to-lot consistency.

Immunogenicity of Catch-Up Immunization with Conventional Inactivated Polio Vaccine among Japanese Adults

Most Japanese adults are vaccinated twice with the Sabin trivalent oral polio vaccine. Booster vaccination is recommended for Japanese travelers to polio-endemic/high-risk countries. We assessed the catch-up immunization of healthy Japanese adults aged ≥20 years with two doses of standalone conventional inactivated polio vaccine (cIPV). Immunogenicity was evaluated by serum neutralization titers (pre-booster vaccination, 4-6 weeks after each vaccination) against type 1, 2, and 3 poliovirus strains. The participants were 61 healthy Japanese adults (26 men/35 women; mean age ± standard deviation age 35.8 ± 8.0 years). Seropositivity rates (percentage of participants with anti-poliovirus antibody titers ≥1:8) pre-vaccination were 88.5%, 95.1%, and 52.5% for Sabin strains (type 1, 2, and 3); 72.1%, 93.4%, and 31.1% for virulent poliovirus strains (type 1: Mahoney; type 2: MEF-1; and type 3: Saukett); and 93.4%, 93.4%, 93.4%, and 88.5% for type 2 vaccine-derived poliovirus strains (SV3128, SV3130, 11,196, and 11,198). After one cIPV dose, all seropositivity rates increased to 98.4-100.0%. After two cIPV doses, the seropositivity rates reached 100% for all strains. cIPV was well tolerated, with no safety concerns. Catch-up immunization with standalone cIPV induced robust immune responses in Japanese adults, indicating that one booster dose boosted serum-neutralizing antibodies to many strains.

Anti-bacterial monoclonal antibodies: next generation therapy against superbugs

Prior to the nineteenth century, infectious disease was one of the leading causes of death. Human life expectancy has roughly doubled over the past century as a result of the development of antibiotics and vaccines. However, the emergence of antibiotic-resistant superbugs brings new challenges. The side effects of broad-spectrum antibiotics, such as causing antimicrobial resistance and destroying the normal flora, often limit their applications. Furthermore, the development of new antibiotics has lagged far behind the emergence and spread of antibiotic resistance. On the other hand, the genome complexity of bacteria makes it difficult to create effective vaccines. Therefore, novel therapeutic agents in supplement to antibiotics and vaccines are urgently needed to improve the treatment of infections. In recent years, monoclonal antibodies (mAbs) have achieved remarkable clinical success in a variety of fields. In the treatment of infectious diseases, mAbs can play functions through multiple mechanisms, including toxins neutralization, virulence factors inhibition, complement-mediated killing activity, and opsonic phagocytosis. Toxins and bacterial surface components are good targets to generate antibodies against. The U.S. FDA has approved three monoclonal antibody drugs, and there are numerous candidates in the preclinical or clinical trial stages. This article reviews recent advances in the research and development of anti-bacterial monoclonal antibody drugs in order to provide a valuable reference for future studies in this area. KEY POINTS: • Novel drugs against antibiotic-resistant superbugs are urgently required • Monoclonal antibodies can treat bacterial infections through multiple mechanisms • There are many anti-bacterial monoclonal antibodies developed in recent years and some candidates have entered the preclinical or clinical stages of development.

The impact of different IPV-OPV sequential immunization programs on hepatitis A and hepatitis B vaccine efficacy

In recent years, the Global Polio Eradication Initiative has gradually implemented a global shift in polio immunization programs. Few studies cover polio immunization program impacts on the efficacy of other vaccines. This study investigated whether polio immunization programs affected hepatitis A (HepA) and hepatitis B (HepB) vaccination efficacy. Serum samples were collected from 968 infants before the first dose of polio vaccine, 28 days after completing primary polio immunization, and at 24 months old. Infants were classified into six polio immunization program groups: 1sIPV+2bOPV, 2sIPV+1bOPV, 2sIPV+1tOPV, 1cIPV+2bOPV, 2cIPV+1bOPV, and 2cIPV+1tOPV (sIPV: Sabin inactivated poliovirus vaccine; cIPV: Salk inactivated poliovirus vaccine; b, bivalent; t, trivalent; OPV, oral polio vaccine). No significant differences existed in antibody titers against HepA virus (anti-HAV) among the polio immunization program groups at any of the three time points (pre-first dose [p = 0.412], 28 days after primary immunization [p = 0.676], 24 months old [p = 0.556]). Before the first dose (p = 0.178) and at age 24 months (p = 0.987), no significant differences existed in HepB surface antibody (HBsAb) titers between the six polio immunization program groups). Twenty-eight days after primary immunization, no significant difference existed in HBsAb titers between groups after Bonferroni correction. Following HepA and HepB immunization, anti-HAV and HBsAb positivity reached > 98% in all groups, reflecting effective immunization. Our data suggest that different polio immunization programs did not affect HepA and HepB vaccine efficacy; HepA and HepB vaccines maintained high effectiveness irrespective of polio immunization program. This trial was registered on Clinical Trials.gov: NCT03614702.

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.

Adverse events and preventive measures related to COVID-19 vaccines

The coronavirus disease 2019 (COVID-19) vaccines are categorized according to the manufacturing technique, including mRNA vaccines and adenovirus vector vaccines. According to previous studies, the reported efficacy of the COVID-19 vaccine is excellent regardless of the type of vaccine, and the majority of studies have shown similar results for safety. Most of the adverse reactions after vaccination were mild or moderate grade, and severe reactions were reported in a very small proportion. However, the adverse reactions that might occur after nationwide vaccinations can contribute to crowding of emergency departments, and this can further lead to significant obstacles to providing necessary treatment for life-threatening conditions. Therefore, as emergency physicians, we would like to present some concerns and suggestions to prevent these predictable problems.

Current development of Zika virus vaccines with special emphasis on virus-like particle technology

Introduction: Zika virus disease received little attention until its recent explosive emergence around the globe. The devastating consequences of this pandemic include congenital Zika syndrome (CZS) and the neurological autoimmune disorder Guillain-Barré syndrome. These potential outcomes prompted massive efforts to understand the course of Zika infection and to develop therapeutic and prophylactic strategies for treatment and prevention of disease.Area covered: Preclinical and clinical data demonstrate that a safe and efficacious vaccine for protection against Zika virus infection is possible in the near future. Nevertheless, significant knowledge gaps regarding the outcome of a mass vaccination strategy exist and must be addressed. Zika virus circulates in flavivirus-endemic regions, an ideal Zika vaccine should avoid the potential of antibody-dependent enhancement from exposure to dengue virus. Prevention of CZS is the primary goal for immunization, and the vaccine must provide protection against intrauterine transmission for use during pregnancy and in women of childbearing age. Ideally, a vaccine should also prevent sexual transmission of the virus through mucosal protection.Expert opinion: This review describes current vaccine approaches against Zika virus with particular attention to the application of virus-like particle (VLP) technology as a strategy for solving the challenges of Zika virus immunization.

An Appraisal of the Current Scenario in Vaccine Research for COVID-19

The recent coronavirus disease 2019 (COVID-19) outbreak has drawn global attention, affecting millions, disrupting economies and healthcare modalities. With its high infection rate, COVID-19 has caused a colossal health crisis worldwide. While information on the comprehensive nature of this infectious agent, SARS-CoV-2, still remains obscure, ongoing genomic studies have been successful in identifying its genomic sequence and the presenting antigen. These may serve as promising, potential therapeutic targets in the effective management of COVID-19. In an attempt to establish herd immunity, massive efforts have been directed and driven toward developing vaccines against the SARS-CoV-2 pathogen. This review, in this direction, is aimed at providing the current scenario and future perspectives in the development of vaccines against SARS-CoV-2.

Overview of Polio Outbreak Response in Kenya, 2013 to 2015

BACKGROUND

Globally, tremendous improvement has been made in Polio eradication since its inception in 1988. For the third time in a decade, Kenya has experienced a Polio outbreak along the border with Somalia. The affected areas were in Garissa County, replete with previous occurrences in 2006 and 2012. This article, give an account of series of events and activities that were used to stop the transmission within 13 weeks, an interval between the first and the last case of the 2013 outbreak.

METHODS

In an attempt to stop further transmission and time bound closure of the outbreak, many activities were brought to fore: the known traditional methods, innovative approaches, improved finances and surge capacity. These assisted in case detection, implementation, and coordination of activities. The external outbreak assessments and the six-monthly technical advisory group recommendations were also employed.

RESULT

There were increased case detections of >=2/100,000, stool adequacy >=80%, due to enhanced surveillance, timely feedbacks from laboratory investigation and diagnosis. Sustained coverage in supplemental immunisation of > 90%, ensured that immune profile of >=3 polio vaccine doses was quickly attained to protect the targeted population, prevent further polio infection and eventual reduction of cases coming up with paralysis.

CONCLUSION

Overall, the outbreak was stopped within the 120 days of the first case using 14 rounds of supplemental immunisation activities.

Post hoc analysis of two clinical trials to compare the immunogenicity and safety of different polio immunization schedules in Chinese infants

Background

A comparative analysis of the immunogenicity and safety of different poliovirus immunization schedules in Chinese infants is imperative to guide the administration of efficient strategies for the eradication of poliomyelitis.

Methods

A post hoc analysis was conducted with the data from two poliovirus vaccine clinical trials involving a combined total of 2,400 infants aged 60–90 days. Trivalent oral poliovirus vaccine (tOPV), bivalent oral poliovirus vaccine (bOPV), Sabin strain-based inactivated poliovirus vaccine (sIPV), and conventional inactivated poliovirus vaccine (cIPV) were used in different schedules, the immunogenicity and safety of which were compared 28 days after the last of three doses.

Results

In a per-protocol set analysis, the tOPV-tOPV-tOPV schedule induced seroconversion in 99.1%, 98.2%, and 96.0% of the inoculated infants for poliovirus type I, II, and III, respectively. The seroconversions for poliovirus types I and III were each almost 100% after immunization with the cIPV-bOPV-bOPV, sIPV-sIPV-bOPV, cIPV-cIPV-bOPV, sIPV-sIPV-tOPV, cIPV-cIPV-tOPV, or sIPV-bOPV-bOPV schedule. However, the schedules that used one IPV dose followed by two (poliovirus type I and III) bOPV doses failed to induce high-level immunity against type II poliovirus. IPV-related schedules were associated with a slightly higher incidence of adverse events (AEs).

Conclusions

If the capacity of IPV can be increased, two or more doses of IPV should be administered before vaccination with bOPV in a sequential schedule to improve immunity against type II poliovirus.

The experiences of using polio outbreak simulation exercises to strengthen national outbreaks preparedness and response plans in sub-Saharan Africa

Introduction

globally, by 2020 the paralytic poliomyelitis disease burden decreased to over 99% of the reported cases in 1988 when resolution 41.8 was endorsed by the World Health Assembly (WHA) for global polio eradication. It is clearly understood that, if there is Wild Poliovirus (WPV) and circulating Vaccines Derived Poliovirus (cVDPV) in the world, no country is safe from polio outbreaks. All countries remain at high risk of re-importation depending on the level of the containment of the types vaccine withdrawn, the laboratory poliovirus isolates, and the population immunity induced by the vaccination program. In this regard, countries to have polio outbreak preparedness and response plans, and conducting the polio outbreak simulation exercises for these plans remain important.

Methods

we conducted a cross-section qualitative study to review to 8 countries conducted polio outbreak simulation exercises in the East and Southern Africa from 2016 to 2018. The findings were categorized into 5 outbreak response thematic areas analyzed qualitatively and summarized them on their strengths and weaknesses.

Results

we found out that, most countries have the overall technical capacities and expertise to deal with outbreaks to a certain extent. Nevertheless, we noted that the national polio outbreak preparedness and response plans were not comprehensive enough to provide proper guidance in responding to outbreaks. The guidelines were inadequately aligned with the WHO POSOPs, and IHR 2005. Additionally, most participants who participated in the simulation exercises were less familiar with their preparedness and response plans, the WHO POSOPs, and therefore reported to be sensitized.

Conclusion

we also realized that, in all countries where the polio simulation exercise conducted, their national polio outbreak preparedness and response plan was revised to be improved in line with the WHO POSOPs and IHR 2005. we, therefore, recommend the polio outbreak simulation exercises to be done in every country with an interval of 3-5 years.

Factors associated with the utilization of inactivated polio vaccine among children aged 12 to 23 months in Kalungu District, Uganda

Uganda officially introduced the inactivated polio vaccine (IPV) in May 2016 as part of the polio eradication strategy and integrated it into its routine immunization programme in addition to the oral polio vaccine. The current coverage stands at 60% as of July 2017. We therefore aimed to determine factors associated with the uptake of IPV among children in Kalungu District so as to inform the implementation of the vaccine policy. A community-based cross-sectional study was conducted among caregivers of 406 eligible children aged 12-23 months through multi-stage systematic sampling and a standardized semi-structured questionnaire. Nine key informant interviews were conducted through purposive selection of health care providers and members of Village Health Teams (VHTs) based on their expertize. Modified Poisson regression and thematic content analysis were used to determine factors significant to IPV uptake among children. 71% of sampled children aged 12-23 months had received IPV in Kalungu District. The survey found that being encouraged by health workers and VHTs was significant to children's uptake of IPV (Adjusted PR 1.24, 95% CI; 1.22-3.47). Distance to the immunization point (Adjusted PR 0.32,95% CI; 0.16-0.62) and caregiver's education level (Adjusted PR 1.16,95% CI; 1.05-2.22) were also associated with IPV uptake. Qualitative findings from health workers and VHT members further confirmed the perception that distance to the immunization post was important, and VHTs also stated that being encouraged by health workers was critical to IPV uptake. The current prevalence of IPV uptake among children aged 12-23 months in Kalungu is 71%, higher than the last reported national coverage (60%), though still below the recommended national coverage of 95%. Efforts should be focused on sensitization of caregivers through health workers and VHTs. Immunization outreach should be strengthened so as to bring services closer to patients.

Vaccine Hesitancy as a Challenge or Vaccine Confidence as an Opportunity for Childhood Immunisation in India

Vaccines have contributed substantially to decreasing the morbidity and mortality rates of many infectious diseases worldwide. Despite this achievement, an increasing number of parents have adopted hesitant behaviours towards vaccines, delaying or even refusing their administration to children. This has implications not only on individuals but also society in the form of outbreaks for e.g. measles, chicken pox, hepatitis A, etc. A review of the literature was conducted to identify the determinants of vaccine hesitancy (VH) as well as vaccine confidence and link them to challenges and opportunities associated with vaccination in India, safety concerns, doubts about the need for vaccines against uncommon diseases and suspicions towards new vaccines were identified as major vaccine-specific factors of VH. Lack of awareness and limited access to vaccination sites were often reported by hesitant parents. Lastly, socio-economic level, educational level and cultural specificities were contextual factors of VH in India. Controversies and rumours around some vaccines (e.g., human papillomavirus) have profoundly impacted the perception of the risks and benefits of vaccination. Challenges posed by traditions and cultural behaviours, geographical specificities, socio-demographic disparities, the healthcare system and vaccine-specific features are highlighted, and opportunities to improve confidence are identified. To overcome VH and promote vaccination, emphasis should be on improving communication, educating the new generation and creating awareness among the society. Tailoring immunisation programmes as per the needs of specific geographical areas or communities is also important to improve vaccine confidence. Fig. 1 Plain language summary.

An epidemiological analysis of Acute Flaccid Paralysis (AFP) surveillance in Kenya, 2016 to 2018

Background

The poliovirus has been targeted for eradication since 1988. Kenya reported its last case of indigenous Wild Poliovirus (WPV) in 1984 but suffered from an outbreak of circulating Vaccine-derived Poliovirus type 2 (cVDPV2) in 2018. We aimed to describe Kenya’s polio surveillance performance 2016–2018 using WHO recommended polio surveillance standards.

Methods

Retrospective secondary data analysis was conducted using Kenyan AFP surveillance case-based database from 2016 to 2018. Analyses were carried out using Epi-Info statistical software (version 7) and mapping was done using Quantum Geographic Information System (GIS) (version 3.4.1).

Results

Kenya reported 1706 cases of AFP from 2016 to 2018. None of the cases were confirmed as poliomyelitis. However, 23 (1.35%) were classified as polio compatible. Children under 5 years accounted for 1085 (63.6%) cases, 937 (55.0%) cases were boys, and 1503 (88.1%) cases had received three or more doses of Oral Polio Vaccine (OPV). AFP detection rate substantially increased over the years; however, the prolonged health workers strike in 2017 negatively affected key surveillance activities. The mean Non-Polio (NP-AFP) rate during the study period was 2.87/ 100,000 children under 15 years, and two adequate specimens were collected for 1512 (88.6%) AFP cases. Cumulatively, 31 (66.0%) counties surpassed target for both WHO recommended AFP quality indicators.

Conclusions

The performance of Kenya’s AFP surveillance system surpassed the minimum WHO recommended targets for both non-polio AFP rate and stool adequacy during the period studied. In order to strengthen the country’s polio free status, health worker’s awareness on AFP surveillance and active case search should be strengthened in least performing counties to improve case detection. Similar analyses should be done at the sub-county level to uncover underperformance that might have been hidden by county level analysis.

Immunogenicity and safety of different sequential schedules of Sabin strain-based inactivated poliovirus vaccination: A randomized, controlled, open-label, phase IV clinical trial in China

BACKGROUND

The immunogenicity and safety of the sequential schedule of Sabin strain-based inactivated poliovirus vaccine (sIPV) and bivalent oral poliovirus vaccine (bOPV) remains poorly understood in Chinese population.

METHODS

A multi-center, open-label, randomized controlled trial was performed involving 648 healthy infants aged 2 months from Inner Mongolia, Shanxi, and Hebei provinces. These participants were divided into three groups: sIPV-bOPV-bOPV, sIPV-sIPV-bOPV, and sIPV-sIPV-sIPV. Doses were administered sequentially at age 2, 3, and 4 months. Neutralisation assays were tested using sera collected at 2 months and 5 months.

RESULTS

A total of 569 were included in the per-protocol analysis. The seroconversion rates of poliovirus type 1 and 3 were 100% in all three groups, the seroconversion rate of poliovirus type 2 was 91.53% (173/189) (95% CI: 86.62-95.08) in the sIPV-bOPV-bOPV group, 98.38% (182/185) (95% CI: 95.33-99.66) in the sIPV-sIPV-bOPV group, and 99.49% (194/195) (95% CI: 97.18-99.99) in the sIPV-sIPV-sIPV group. For the seroconversion rate of poliovirus types 1 and 3, the sIPV-bOPV-bOPV and sIPV-sIPV-bOPV groups were non-inferior to the sIPV-sIPV-sIPV group. For the seroconversion rate of poliovirus type 2, the sIPV-sIPV-bOPV group was non-inferior to the sIPV-sIPV-sIPV group, and the sIPV-bOPV-bOPV group was inferior to the sIPV-sIPV-sIPV group. All three groups exhibited good safety, with two serious adverse events reported, that were unrelated to vaccine.

CONCLUSIONS

In china, a new vaccination schedule that including 2 doses of IPV in the national immunization programs is essential. Trial registration ClinicalTrials.govNCT04054492.

Influence of gut microbiota on mucosal IgA antibody response to the polio vaccine

The impact of intestinal microbiota on mucosal antibody response to the polio vaccine is poorly understood. We examined changes in vaccine-induced intestinal mucosal immunity to poliovirus by measuring the immunoglobulin A (IgA) antibody levels in stool samples collected from 107 infants in China, and the samples were collected 14 days after different sequential vaccinations combining inactivated polio vaccine (IPV) with oral poliovirus vaccine (OPV). Gut microbiota were identified using 16S ribosomal RNA sequencing 28 days before, 14 days before, and at the last dose of OPV. Vaccine-induced type 2-specific mucosal IgA showed a decrease after switching from trivalent to bivalent OPV (bOPV) (positive rate of polio type 2-specific mucosal IgA, 16.7%, 11.8%, and 45.9% for IPV + 2bOPV, 2IPV + bOPV, and 2IPV + trivalent OPV groups, respectively). The composition of the gut microbiome was significantly different, a higher abundance of Firmicutes and a lower abundance of Actinobacteria were observed in IgA-negative infant (n = 66) compared with IgA-positive infants (n = 39), and the gut microbiota were more diverse in IgA-negative infants on the day of OPV inoculation. The abundance of Clostridia was concomitant with a significantly lower conversion rate of mucosal IgA responses to the polio vaccine. The composition of the gut microbiome may affect the intestinal mucosal IgA response to the polio vaccine.

Immunogenicity and Safety of a Sabin Strain-Based Inactivated Polio Vaccine: A Phase 3 Clinical Trial

BACKGROUND

The Sabin strain-based inactivated polio vaccine (sIPV) plays a vital role in eradicating poliomyelitis in developing countries.

METHODS

The study was designed as a randomized, controlled, double-blinded, noninferiority trial. A total of 1200 healthy infants aged 60-90 days were enrolled and randomly assigned to receive 3 doses of either sIPV (the experimental arm) or IPV (the control arm) at days 0, 30, and 60. Immunogenicity and safety outcomes were assessed using the per-protocol and safety populations, respectively.

RESULTS

A total of 553 and 562 participants in the sIPV and IPV groups, respectively, were included in the per-protocol population. Seroconversion rates in the sIPV and IPV groups were 98.0% and 94.1%, respectively, for type 1 poliovirus (P < .01); 94.8% and 84.0%, respectively, for type 2 (P < .01); and 98.9% and 97.7%, respectively, for type 3 (P = .11). A total of 599 and 600 participants in the sIPV and IPV groups, respectively, were included in the safety population. Fever was the most common adverse event, occurring in 61.6% and 49.8% of participants in the experimental and control arms, respectively (P < .01).

CONCLUSIONS

The sIPV demonstrated an immunogenicity profile noninferior to that of the conventional IPV and had a good safety profile.

CLINICAL TRIALS REGISTRATION

NCT03526978.

Genotype-Specific Neutralization of Norovirus Is Mediated by Antibodies Against the Protruding Domain of the Major Capsid Protein

Human noroviruses are the most common viral agents of acute gastroenteritis. Recently, human intestinal enteroids were shown to be permissive for norovirus infection. We tested their suitability as a system to study norovirus neutralization. Hyperimmune sera raised against virus-like particles (VLPs) representing different genotypes showed highly specific neutralization activity against GII.4 and GII.6 noroviruses. Carbohydrate blocking assays and neutralization exhibited similar patterns in antibody responses. Notably, sera produced against chimeric VLPs that presented swapped structural shell and protruding (P) domains, from different genotypes showed that neutralization is primarily mediated by antibodies mapping to the P domain of the norovirus capsid protein. This study provides empirical information on the antigenic differences among genotypes as measured by neutralization, which could guide vaccine design.

A novel gamma radiation-inactivated sabin-based polio vaccine

A concerted action on the part of international agencies and national governments has resulted in the near-eradication of poliomyelitis. However, both the oral polio vaccine (OPV) and the inactivated polio vaccine (IPV) have deficiencies which make them suboptimal for use after global eradication. OPV is composed of attenuated Sabin strains and stimulates robust immunity, but may revert to neurovirulent forms in the intestine which can be shed and infect susceptible contacts. The majority of IPV products are manufactured using pathogenic strains inactivated with formalin. Upon eradication, the production of large quantities of pathogenic virus will present an increased biosecurity hazard. A logical ideal endgame vaccine would be an inactivated form of an attenuated strain that could afford protective immunity while safely producing larger numbers of doses per unit of virus stock than current vaccines. We report here the development of an ionizing radiation (IR)-inactivated Sabin-based vaccine using a reconstituted Mn-decapeptide (MDP) antioxidant complex derived from the radioresistant bacterium Deinococcus radiodurans. In bacteria, Mn2+-peptide antioxidants protect proteins from oxidative damage caused by extreme radiation exposure. Here we show for the first time, that MDP can protect immunogenic neutralizing epitopes in picornaviruses. MDP protects epitopes in Polio Virus 1 and 2 Sabin strains (PV1-S and PV2-S, respectively), but viral genomic RNA is not protected during supralethal irradiation. IR-inactivated Sabin viruses stimulated equivalent or improved neutralizing antibody responses in Wistar rats compared to the commercially used IPV products. Our approach reduces the biosecurity risk of the current PV vaccine production method by utilizing the Sabin strains instead of the wild type neurovirulent strains. Additionally, the IR-inactivation approach could provide a simpler, faster and less costly process for producing a more immunogenic IPV. Gamma-irradiation is a well-known method of virus inactivation and this vaccine approach could be adapted to any pathogen of interest.

Glutathione facilitates enterovirus assembly by binding at a druggable pocket

Enteroviruses cause a range of human and animal diseases, some life-threatening, but there remain no licenced anti-enterovirus drugs. However, a benzene-sulfonamide derivative and related compounds have been shown recently to block infection of a range of enteroviruses by binding the capsid at a positively-charged surface depression conserved across many enteroviruses. It has also been established that glutathione is essential for the assembly of many enteroviruses, interacting with the capsid proteins to facilitate the formation of the pentameric assembly intermediate, although the mechanism is unknown. Here we show, by high resolution structure analyses of enterovirus F3, that reduced glutathione binds to the same interprotomer pocket as the benzene-sulfonamide derivative. Bound glutathione makes strong interactions with adjacent protomers, thereby explaining the underlying biological role of this druggable binding pocket and delineating the pharmacophore for potential antivirals.

Immune Priming and Long-term Persistence of Memory B Cells After Inactivated Poliovirus Vaccine in Macaque Models: Support for at least 2 Doses

Background

As a risk-mitigation strategy to minimize paralytic polio following withdrawal of Sabin type 2 from the oral poliovirus vaccine in April 2016, a single full dose or 2 fractional doses of inactivated poliovirus vaccine (IPV) are recommended. However, limited knowledge exists on long-term persistence of immune memory following 1- or 2-dose IPV schedules.

Methods

We examined induction and maintenance of immune memory following single- vs 2-dose IPV schedules, either full-dose intramuscular or fractional-dose intradermal, in rhesus macaques. Humoral responses, bone marrow–homing antibody-secreting plasma cells, and blood-circulating/lymph node–homing memory B cells were examined longitudinally.

Results

A single dose of IPV, either full or fractional, induced binding antibodies and memory B cells in all vaccinated macaques, despite failing to induce neutralizing antibodies (NT Abs) in many of them. However, these memory B cells declined rapidly, reaching below detection in the systemic circulation by 5 months; although a low frequency of memory B cells was detectable in draining lymph nodes of some, but not all, animals. By contrast, a 2-dose vaccination schedule, either full or fractional, efficiently induced NT Abs in all animals along with bone marrow–homing plasma cells and memory B cells. These memory B cells persisted in the systemic circulation for up to 16 months, the maximum duration tested after the second dose of vaccination.

Conclusions

Two doses of IPV, regardless of whether fractional or full, are more effective than a single dose for inducing long-lasting memory B cells.

Mobilizing political support proved critical to a successful switch from tOPV to bOPV in Kano, Nigeria 2016

BACKGROUND

Kano is one of the high-risk states for polio transmission in Northern Nigeria. The state reported more cases of wild polioviruses (WPVs) than any other state in the country. The Nigeria Demographic and Health Survey of 2013 indicated that OPV3 coverage in the routine immunization (RI) programmewas 57.9%. Additionally, serial polio seroprevalence studies conducted from 2011 to 2015 in the eightmetropolitan LGAs indicated low immunity levels against all three polio serotypes in children below one year. Areas with sub-optimal RI coverage such as Kanothat fail to remove all tOPV during the tOPV-bOPV switchwill be at increased risk of VDPV2 circulation.

METHODS

We assessed the impact of political leadership engagement in mobilizing other stakeholders on the outcomes of the bOPV-tOPV switch in Kano State from February to May 2016 using nationally-selected planning and outcome indicators.

RESULTS

A total of 670 health facilities that provide RI services were assessed during the pre-switch activities. Health workers were aware of the switch exercise in 520 (95.1%) of the public health facilities assessed. It was found that health workers knew what to do should tOPV be found in any of the 521 (95.2%)public health facilities assessed. However, there was a wide disparity between the public and private health practitioners' knowledge on basic concepts of the switch. There was 100% withdrawal of tOPV from the state and the seven zonal cold stores. Unmarked tOPVwas found in the cold chain system in 2 (4.5%) LGAs. Only one health facility (0.8%) had tOPV in the cold chain. No tOPVwas identified outside the cold chain without the "Do not use" sticker in any of the health facilities.

CONCLUSION

The engagement of the political leadership to mobilize other key stakeholders facilitated successful implementation of the tOPV-bOPVswitch exercise and provided opportunity to strengthen partnerships with the private health sector in Kano State.

Routine immunization community surveys as a tool for guiding program implementation in Kaduna state, Nigeria 2015-2016

Background

Routine childhood immunization remains an important strategy for achieving polio eradication and maintaining a polio-free world. To address gaps in reported administrative coverage data, community surveys were conducted to verify coverage, and guide strategic interventions for improved coverage.

Methods

We reviewed the conduct of community surveys by World Health Organization (WHO) field volunteers deployed as part of the surge capacity to Kaduna state and the use of survey results between July 2015 and June 2016. Monthly and quarterly collation and use of these data to guide the deployment of various interventions aimed at strengthening routine immunization in the state.

Results

Over 97,000 children aged 0–11 months were surveyed by 138 field volunteers across 237 of the 255 wards in Kaduna state. Fully or appropriately immunized children increased from 67% in the fourth quarter of 2015 to 76% by the end of the second quarter of 2016. Within the period reviewed, the number of local government areas with < 80% coverage reduced from eight to zero.

Conclusions

The routine conduct of community surveys by volunteers to inform interventions has shown an improvement in the vaccination status of children 0–11 months in Kaduna state and remains a useful tool in addressing administrative data quality issues.

Characterization of an inactivated whole-virus bivalent vaccine that induces balanced protective immunity against coxsackievirus A6 and A10 in mice

Coxsackievirus A6 (CVA6) and CVA10 are two of the major pathogens associated with hand, foot and mouth disease (HFMD) in children. The majority of CVA6 and CVA10 infections result in mild, self-limiting episodes (fever and herpangina) in pediatric populations; however, in some cases, can proceed to severe neurological disease and death. Efforts to mitigate viral transmission to decrease the morbidity and mortality associated with infection would be greatly strengthened by the availability of an efficacious CVA6 and CVA10 bivalent vaccine. Here we report the immunogenicity and protective efficacy of a bivalent combination vaccine comprised of formaldehyde-inactivated, whole-virus CVA6 and CVA10. We demonstrate that subcutaneous delivery of the bivalent vaccine can induce antigen-specific systemic immune responses, particularly the induction of polyfunctional T cells, which elicit active immunization to achieve a protection rate of >80% in the infected neonatal mice. Furthermore, passive transfer of the antisera from vaccinated mice potently protected recipient mice against CVA6 and CVA10 challenge. Importantly, the bivalent vaccine could induce high levels of IgG and neutralizing antibodies in adult female mice and the maternal antibody transmitted to the recipient mice played an important role in controlling homotypic and heterotypic CVA6 and CVA10 infections and viral replication in vivo. Collectively, these findings indicate that there is no immunological interference between the two antigens with respect to their ability to induce virus-specific immune responses, and thus provides proof-of-concept for further development of multivalent vaccines for broad protection against HFMD.

Immunogenicity of sequential inactivated and oral poliovirus vaccines (OPV) versus inactivated poliovirus vaccine (IPV) alone in healthy infants: A systematic review and meta-analysis

BACKGROUND

The emergence of vaccine-associated paralytic poliomyelitis has become an ongoing burden of poliomyelitis. During this special period from OPV to IPV-only immunization schedule, we did a meta-analysis to compare the immunogenicity of sequential IPV and OPV versus IPV alone in healthy infants.

METHODS

This systematic review and meta-analysis was registered at international prospective register of systematic reviews (PROSPERO), and the number was CRD42017054889. We performed it as described.

RESULTS

Finally, 6 articles were qualified for our review. The results showed that seroconversion rates against all 3 serotype polioviruses were non-inferior and Geometric mean antibody titers (GMTs) were superior in sequential schedules compared with IPV-only schedule. Thus, the sequential vaccination schedules could induce a stronger immunogenicity.

CONCLUSIONS

To decrease vaccine-associated and vaccine-derived poliomyelitis, it is a reasonable option to select sequential schedules during this special transition from OPV to IPV-only immunization schedule, which coincides with the current WHO recommendations.

Advances and Opportunities in Nanoparticle- and Nanomaterial-Based Vaccines against Bacterial Infections

As the dawn of the postantibiotic era we approach, antibacterial vaccines are becoming increasingly important for managing bacterial infection and reducing the need for antibiotics. Despite the success of vaccination, vaccines remain unavailable for many pressing microbial diseases, including tuberculosis, chlamydia, and staphylococcus infections. Amid continuing research efforts in antibacterial vaccine development, the advancement of nanomaterial engineering has brought forth new opportunities in vaccine designs. With increasing knowledge in antibacterial immunity and immunologic adjuvants, innovative nanoparticles are designed to elicit the appropriate immune responses for effective antimicrobial defense. Rationally designed nanoparticles are demonstrated to overcome delivery barriers to shape the adaptive immunity. This article reviews the advances in nanoparticle- and nanomaterial-based antibacterial vaccines and summarizes the development of nanoparticulate adjuvants for immune potentiation against microbial pathogens. In addition, challenges and progress in ongoing antibacterial vaccine development are discussed to highlight the opportunities for future vaccine designs.

Determinants of the receipt of the 9-valent human papillomavirus vaccine in the first year after introduction in North Carolina

OBJECTIVES

The objective of this study was to describe the transition from bi- and quadrivalent HPV vaccines to 9vHPV in aggregate and identify determinants of the receipt of 9vHPV among youth following the introduction of 9vHPV in North Carolina.

METHODS

The study used a retrospective cohort design with data from the North Carolina Immunization Registry (NCIR). Our sample included all doses of HPV vaccine administered between July 2015 and October 2016 to age-eligible youth (ages 9-17). We used a logistic regression model to associate individual child-level and ZIP Code Tabulation Area (ZCTA)-level characteristics with an indicator variable for receiving 9vHPV (vs. other HPV vaccines).

RESULTS

Youth receiving the HPV vaccine were more likely to receive 9vHPV if they lived in a ZCTA with a larger age-eligible (i.e., 9-17) population, a health professional shortage area, or a higher number of annual outpatient visits per capita. They were less likely to receive 9vHPV if they were older, received a publicly-funded dose, or lived in a ZCTA with a higher percentage of the population with less than a high-school education or a higher number of religious organizations.

CONCLUSIONS

While the transition from other HPV vaccines to 9vHPV was relatively quick, there were disparities in the diffusion of 9vHPV across North Carolina.

Impact of introduction of the 9-valent human papillomavirus vaccine on vaccination coverage of youth in North Carolina

OBJECTIVES

The objective of this study was to evaluate the impact of introduction of 9vHPV vaccine on HPV vaccination uptake (doses per capita) and initiation (≥1 doses), completion (≥3 doses) and compliance (≥3 doses within 12 months) by adolescents.

METHODS

We used a retrospective cohort analysis using North Carolina Immunization Registry (NCIR) data from January 2008 through October 2016. The sample included Vaccines for Children eligible adolescents aged 9 to 17 years in 2016, for whom the NCIR contains complete vaccination history. We applied an interrupted time series design to measure associations between ZIP Code Tabulation Area (ZCTA)-level HPV vaccination outcomes over time with the introduction of 9vHPV in North Carolina (NC) in July 2015.

RESULTS

Each outcome displayed a linear upward trend over time with large seasonal spikes near August of each year, corresponding to the time when adolescents often receive other vaccines required for school entry. After accounting for these underlying trends, introduction of 9vHPV was not associated with a change in publicly funded HPV vaccination rates in NC.

CONCLUSIONS

Our results indicate that 9vHPV substituted for 4vHPV in the first year after release in NC, but the release of 9vHPV was not associated with an overall change in HPV vaccination.

Assessment of source of information for polio supplementary immunization activities in 2014 and 2015, Somali, Ethiopia

INTRODUCTION

Communication is key for the successful implementation of polio vaccination campaigns. The purpose of this study is to review and analyse the sources of information utilized by caregivers during polio supplementary immunization activities (SIAs) in Somali, Ethiopia in 2014 and 2015.

METHODS

Data on sources of information about the polio campaign were collected post campaign from caregivers by trained data collectors as part of house to house independent monitoring. The sources of information analysed in this paper include town criers (via megaphones), health workers, religious leaders, kebele leaders (Kebele is the lowest administrative structure in Ethiopia), radio, television, text message and others. The repetition of these sources of information was analysed across years and zones for trends. Polio vaccination campaign coverage was also reviewed by year and zones within the Somali region in parallel with the major sources of information used in the respective year and zones. 57,745 responses were used for this analysis but the responses were received from < or = 57,745 individuals since some of them may provide more than one response. Moreover, because sampling of households is conducted independently during each round of independent monitoring, the same household may have been included more than once in our analysis. The methodology used for independent monitoring does not allow for the calculation of response rates. Monitors go from house to house until information from 20 households is received.

RESULTS

From the total 57,745 responses reviewed, over 37% of respondents reported that town criers were their source for information about the 2014 and 2015 polio SIAs. Zonal trends in using town criers as a major source of information in both study years remained consistent except in two zones. 87.5% of zones that reported at least 90% coverage during both study years had utilized town criers as a major source of information while the rest (12.5%) used health workers.

CONCLUSION

We found that town criers were consistently the major source of information about the polio campaigns for Somali region parents and caregivers during polio immunization days held in 2014 and 2015. Health workers and kebele leaders were also important sources of information about the polio campaign for parents.

Addressing the Challenges and Opportunities of the Polio Endgame: Lessons for the Future

The Global Commission for the Certification of the Eradication of Poliomyelitis certified the eradication of type 2 poliovirus in September 2015, making type 2 poliovirus the first human pathogen to be eradicated since smallpox. The eradication of type 2 poliovirus, the absence of detection of type 3 poliovirus worldwide since November 2012, and cornering type 1 poliovirus to only a few geographic areas of 3 countries has enabled implementation of the endgame of polio eradication which calls for a phased withdrawal of oral polio vaccine beginning with the type 2 component, introduction of inactivated poliovirus vaccine, strengthening of routine immunization in countries with extensive polio resources, and initiating activities to transition polio resources, program experience, and lessons learned to other global health initiatives. This supplement focuses on efforts by global partners to successfully launch polio endgame activities to permanently secure and sustain the enormous gains of polio eradication forever.

Adjuvant formulations for virus-like particle (VLP) based vaccines

The development of virus-like particle (VLP) technology has had an enormous impact on modern vaccinology. In order to optimize the efficacy and safety of VLP-based vaccines, adjuvants are included in most vaccine formulations. To date, most licensed VLP-based vaccines utilize the classic aluminum adjuvant compositions. Certain challenging pathogens and weak immune responder subjects may require further optimization of the adjuvant formulation to maximize the magnitude and duration of the protective immunity. Indeed, novel classes of adjuvants such as liposomes, agonists of pathogen recognition receptors, polymeric particles, emulsions, cytokines and bacterial toxins, can be used to further improve the immunostimulatory activity of a VLP-based vaccine. This review describes the current advances in adjuvant technology for VLP-based vaccines directed at viral diseases, and discusses the basic principles for designing adjuvant formulations for enhancing the vaccine immunogenicity.

Implementing the Synchronized Global Switch from Trivalent to Bivalent Oral Polio Vaccines-Lessons Learned From the Global Perspective

In 2015, the Global Commission for the Certification of Polio Eradication certified the eradication of type 2 wild poliovirus, 1 of 3 wild poliovirus serotypes causing paralytic polio since the beginning of recorded history. This milestone was one of the key criteria prompting the Global Polio Eradication Initiative to begin withdrawal of oral polio vaccines (OPV), beginning with the type 2 component (OPV2), through a globally synchronized initiative in April and May 2016 that called for all OPV using countries and territories to simultaneously switch from use of trivalent OPV (tOPV; containing types 1, 2, and 3 poliovirus) to bivalent OPV (bOPV; containing types 1 and 3 poliovirus), thus withdrawing OPV2. Before the switch, immunization programs globally had been using approximately 2 billion tOPV doses per year to immunize hundreds of millions of children. Thus, the globally synchronized withdrawal of tOPV was an unprecedented achievement in immunization and was part of a crucial strategy for containment of polioviruses. Successful implementation of the switch called for intense global coordination during 2015-2016 on an unprecedented scale among global public health technical agencies and donors, vaccine manufacturers, regulatory agencies, World Health Organization (WHO) and United Nations Children's Fund (UNICEF) regional offices, and national governments. Priority activities included cessation of tOPV production and shipment, national inventories of tOPV, detailed forecasting of tOPV needs, bOPV licensing, scaling up of bOPV production and procurement, developing national operational switch plans, securing funding, establishing oversight and implementation committees and teams, training logisticians and health workers, fostering advocacy and communications, establishing monitoring and validation structures, and implementing waste management strategies. The WHO received confirmation that, by mid May 2016, all 155 countries and territories that had used OPV in 2015 had successfully withdrawn OPV2 by ceasing use of tOPV in their national immunization programs. This article provides an overview of the global efforts and challenges in successfully implementing this unprecedented global initiative, including (1) coordination and tracking of key global planning milestones, (2) guidance facilitating development of country specific plans, (3) challenges for planning and implementing the switch at the global level, and (4) best practices and lessons learned in meeting aggressive switch timelines. Lessons from this monumental public health achievement by countries and partners will likely be drawn upon when bOPV is withdrawn after polio eradication but also could be relevant for other global health initiatives with similarly complex mandates and accelerated timelines.

The Role of National Immunization Technical Advisory Groups (NITAGs) in the Introduction of Inactivated Polio Vaccine: Experience of the Indonesia and Uganda NITAGs

Background

National Immunization Technical Advisory Groups (NITAGs) are established by national authorities to provide them with independent, bias-free, objective, and evidence-based advice on vaccines and immunization challenges. As of December 2015, 125 countries have reported having set up an NITAG. The Health Policy and Institutional Development Center at the Agence de Médecine Préventive, a World Health Organization (WHO) Collaborative Center for evidence-informed immunization, through its Supporting Independent Immunization and Vaccine Advisory Committees (SIVAC) Initiative project, provides assistance to low- and middle-income countries in the establishment and strengthening of their NITAGs. The Indonesian NITAG (ITAGI) was formed in December 2006 and Uganda's (UNITAG) was formed in November 2014. Both Uganda and Indonesia have introduced inactivated polio vaccine (IPV) as part of the Global Polio Eradication and Endgame Strategic Plan (the Endgame plan). The authors reflect on the process and the role played by NITAGs in the introduction of IPV in the routine immunization program and the lessons learned.

Methods

This commentary is a reflection of the authors' experience on NITAG's role as observed in 2 particular local settings and applied to a global public health issue, the polio eradication Endgame plan. The reflection is backed up by the relevant (policy and technical) documents on polio eradication, along with minutes and reports from countries' ministries of health, immunization programs, WHO, and NITAGs.

Results

NITAGs are valuable tools for ministries of health to ensure sustainable, evidence-informed immunization policies that are trusted and accepted by their communities. Early engagement with NITAGs also ensures that the adoption of strategies addressing global public health threats at the country level reinforces the national immunization programs. On the other end, when NITAGs are proactive and forward-thinking, they can contribute to a smooth and effective introduction of the above-mentioned strategies. Time and resources are key factors to ensure optimal performance of NITAGs.

The polio endgame: rationale behind the change in immunisation

The decades long effort to eradicate polio is nearing the final stages and oral polio vaccine (OPV) is much to thank for this success. As cases of wild poliovirus continue to dwindle, cases of paralysis associated with OPV itself have become a concern. As type-2 poliovirus (one of three) has been certified eradicated and a large proportion of OPV-related paralysis is caused by the type-2 component of OPV, the World Health Assembly endorsed the phased withdrawal of OPV and the introduction of inactivated polio vaccine (IPV) into routine immunisation schedules as a crucial step in the polio endgame plan. The rapid pace of IPV scale-up and uptake required adequate supply, planning, advocacy, training and operational readiness. Similarly, the synchronised switch from trivalent OPV (all three types) to bivalent OPV (types 1 and 3) involved an unprecedented level of global coordination and country commitment. The important shift in vaccination policy seen through global IPV introduction and OPV withdrawal represents an historical milestone reached in the polio eradication effort.

Immunogenicity and safety evaluation of bivalent types 1 and 3 oral poliovirus vaccine by comparing different poliomyelitis vaccination schedules in China: A randomized controlled non-inferiority clinical trial

BACKGROUND

The type 2 component of the oral poliovirus vaccine is targeted for global withdrawal through a switch from the trivalent oral poliovirus vaccine (tOPV) to a bivalent oral poliovirus vaccine (bOPV). The switch is intended to prevent paralytic polio caused by circulating vaccine-derived poliovirus type 2. We aimed to assess the immunogenicity and safety profile of 6 vaccination schedules with different sequential doses of inactivated poliovirus vaccine (IPV), tOPV, or bOPV.

METHODS

A randomized controlled trial was conducted in China in 2015. Healthy newborn babies randomly received one of the following 6 vaccination schedules: cIPV-bOPV-bOPV(I-B-B), cIPV-tOPV-tOPV(I-T-T), cIPV-cIPV-bOPV(I-I-B), cIPV-cIPV-tOPV(I-I-T), cIPV-cIPV-cIPV(I-I-I), or tOPV-tOPV-tOPV(T-T-T). Doses were administered sequentially at 4-6 week intervals after collecting baseline blood samples. Patients were proactively followed up for observation of adverse events after the first dose and 30 days after all doses. The primary study objective was to investigate the immunogenicity and safety profile of different vaccine schedules, evaluated by seroconversion, seroprotection and antibody titer against poliovirus types 1, 2, and 3 in the per-protocol population.

RESULTS

Of 600 newborn babies enrolled, 504 (84.0%) were included in the per-protocol population. For type 1 poliovirus, the differences in the seroconversion were 1.17% (95% CI = -2.74%, 5.08%) between I-B-B and I-T-T and 0.00% (95% CI: -6.99%, 6.99%) between I-I-B and I-I-T; for type 3 poliovirus, differences in the seroconversion were 3.49% (95% CI: -1.50%, 8.48%) between I-B-B and I-T-T and -2.32% (95% CI: -5.51%, 0.86%) between I-I-B and I-I-T. The non-inferiority conclusion was achieved in both poliovirus type 1 and 3 with the margin of -10%. Of 24 serious adverse events reported, no one was vaccine-related.

CONCLUSIONS

The vaccination schedules with bOPV followed by one or 2 doses of IPV were recommended to substitute for vaccinations involving tOPV without compromising the immunogenicity and safety in the Chinese population. The findings will be essential for policy formulation by national and global authorities to facilitate polio elimination.

The potential benefits of a new poliovirus vaccine for long-term poliovirus risk management

Aim: To estimate the incremental net benefits (INBs) of a hypothetical ideal vaccine with all of the advantages and no disadvantages of existing oral and inactivated poliovirus vaccines compared with current vaccines available for future outbreak response. Methods: INB estimates based on expected costs and polio cases from an existing global model of long-term poliovirus risk management. Results: Excluding the development costs, an ideal poliovirus vaccine could offer expected INBs of US$1.6 billion. The ideal vaccine yields small benefits in most realizations of long-term risks, but great benefits in low-probability–high-consequence realizations. Conclusion: New poliovirus vaccines may offer valuable insurance against long-term poliovirus risks and new vaccine development efforts should continue as the world gathers more evidence about polio endgame risks.

Polio endgame: the global switch from tOPV to bOPV

Globally, polio cases have reached an all-time low, and type 2 poliovirus (one of three) is eradicated. Oral polio vaccine (OPV) has been the primary tool, however, in rare cases, OPV induces paralysis. In 2013, the World Health Assembly endorsed the phased withdrawal of OPV and introduction of inactivated poliovirus vaccine (IPV) into childhood routine immunization schedules. Type 2 OPV will be withdrawn through a globally synchronized "switch" from trivalent OPV (all three types) to bivalent OPV (types 1 and 3). The switch will happen in 155 OPV-using countries between April 17(th) and May 1(st), 2016. Planned activities to reduce type 2 outbreak risks post-switch include the following: tOPV campaigns to increase type 2 immunity prior to the switch, monovalent OPV2 stockpiling to respond to outbreaks should they occur, containment of both wild and vaccine type 2 viruses, enhanced acute flaccid paralysis (AFP) and environmental surveillance, outbreak response protocols, and ensured access to IPV and bivalent OPV.

Enhancing Vaccine Safety Capacity Globally: A Lifecycle Perspective

Major vaccine safety controversies have arisen in several countries beginning in the last decades of 20th century. Such periodic vaccine safety controversies are unlikely to go away in the near future as more national immunization programs mature with near elimination of target vaccine-preventable diseases that result in relative greater prominence of adverse events following immunizations, both true reactions and temporally coincidental events. There are several ways in which vaccine safety capacity can be improved to potentially mitigate the impact of future vaccine safety controversies. This paper aims to take a "lifecycle" approach, examining some potential pre- and post-licensure opportunities to improve vaccine safety, in both developed (specifically U.S. and Europe) and low- and middle-income countries.

The Challenge of Global Poliomyelitis Eradication

In the United States during the 1950's, polio was on the forefront of every provider and caregiver's mind. Today, most providers in the United States have never seen a case. The Global Polio Eradication Initiative (GPEI), which began in 1988 has reduced the number of cases by over 99%. The world is closer to achieving global eradication of polio than ever before but as long as poliovirus circulates anywhere in the world, every country is vulnerable. The global community can support the polio eradication effort through continued vaccination, surveillance, enforcing travel regulations and contributing financial support, partnerships and advocacy.