Vaccine-Derived Poliovirus Infection among Patients with Primary Immunodeficiency and Effect of Patient Screening on Disease Outcomes, Iran

Patients with immunodeficiency-associated vaccine-derived poliovirus (iVDPV) are potential poliovirus reservoirs in the posteradication era that might reintroduce polioviruses into the community. We update the iVDPV registry in Iran by reporting 9 new patients. In addition to national acute flaccid paralysis surveillance, cases were identified by screening nonparalyzed primary immunodeficiency (PID) patients. Overall, 23 iVDPV patients have been identified since 1995. Seven patients (30%) never had paralysis. Poliovirus screening accelerated the iVDPV detection rate in Iran after 2014.The iVDPV infection rate among nonparalyzed patients with adaptive PID was 3.1% (7/224), several folds higher than previous estimates. Severe combined immunodeficiency patients had the highest risk for asymptomatic infection (28.6%) compared with other PIDs. iVDPV2 emergence has decreased after the switch from trivalent to bivalent oral poliovirus vaccine in 2016. However, emergence of iVDPV1 and iVDPV3 continued. Poliovirus screening in PID patients is an essential step in the endgame of polio eradication.

A comparative assessment of cold chain management using the outbreak of circulating vaccine-derived polio virus type 2 as a surrogate marker in Oyo State, Nigeria-2019

Introduction

inspite of the demonstrable evidence of the preventive and protective ability of vaccines to reduce the outbreak of vaccine-preventable diseases, there are still some significant disease outbreaks recorded in our communities. In some settings, these outbreaks have been linked with poor vaccine management. Therefore, this study was conducted to compare the cold chain practices in Oyo State, Nigeria.

Methods

we conducted a cross-sectional survey among health workers in the local government areas of Oyo State between October and November 2019. Using purposive sampling, we recruited all the 84 routine immunization focal persons for the study. A self-administered questionnaire was used to collect data on cold chain management. Data were analyzed using SPSS version 24 and bivariate analysis was done using Chi-square. Statistical significance was set at p < 0.05.

Results

the mean age of the respondents was 46.4 ± 6.7 years. Most prevalent cadre in the rural facilities was health assistants (87.5%) while Community Extension Health Workers (54.8%) were prevalent in the urban (p = 0.002). The proportion of respondents with adequate cold chain equipment was significantly higher in the urban compared with the rural area. The cold boxes were the only adequate cold chain equipment found in the rural health facilities compared with the urban (p = 0.036).

Conclusion

there was a low proportion of qualified health workers and inadequate cold chain equipment in the rural area compared with the urban facilities. Engagement of skilled health workers and supply of the cold chain equipment are recommended.

Completeness and timeliness of diphtheria-tetanus-pertussis, measles-mumps-rubella, and polio vaccines in young children with chronic health conditions: A systematic review

OBJECTIVE

To systematically review literature on uptake and timeliness of diphtheria-tetanus-pertussis, measles-mumps-rubella, and/or polio-containing vaccines ininfants who were born preterm, with a low birth weight, and/or with chronic health conditions that were diagnosed within the first 6 months of life.

METHODS

Using a standardized search strategy developed by a medical librarian, records were extracted from MEDLINE, Embase, Database of Abstracts of Reviews of Effects, and CINAHL up to May 8, 2018.

RESULTS

Out of the 1997 records that were screened, we identified 21 studies that met inclusion criteria. Eleven studies assessed vaccine coverage and/or timeliness in preterm infants, 6 in low birth weight infants, and 7 in children with chronic health conditions. Estimates of coverage in these populations were highly variable, ranging from 40% to 100% across the vaccines and population groups.

CONCLUSIONS

There is a lack of studies reporting coverage and timeliness of routine immunizations in special populations of children.

POLICY IMPLICATIONS

Our review suggests a need for improved surveillance of immunization status in special populations of infants, as wellas aneed for standardization of reporting practices.

Plant-made polio type 3 stabilized VLPs-a candidate synthetic polio vaccine

Poliovirus (PV) is the causative agent of poliomyelitis, a crippling human disease known since antiquity. PV occurs in two distinct antigenic forms, D and C, of which only the D form elicits a robust neutralizing response. Developing a synthetically produced stabilized virus-like particle (sVLP)-based vaccine with D antigenicity, without the drawbacks of current vaccines, will be a major step towards the final eradication of poliovirus. Such a sVLP would retain the native antigenic conformation and the repetitive structure of the original virus particle, but lack infectious genomic material. In this study, we report the production of synthetically stabilized PV VLPs in plants. Mice carrying the gene for the human PV receptor are protected from wild-type PV when immunized with the plant-made PV sVLPs. Structural analysis of the stabilized mutant at 3.6 Å resolution by cryo-electron microscopy and single-particle reconstruction reveals a structure almost indistinguishable from wild-type PV3.Despite the success of current vaccination against poliomyelitis, safe, cheap and effective vaccines remain sought for continuing eradication effort. Here the authors use plants to express stabilized virus-like particles of type 3 poliovirus that can induce a protective immune response in mice transgenic for the human poliovirus receptor.

Genetically Thermo-Stabilised, Immunogenic Poliovirus Empty Capsids; a Strategy for Non-replicating Vaccines

While wild type polio has been nearly eradicated there will be a need to continue immunisation programmes for some time because of the possibility of re-emergence and the existence of long term excreters of poliovirus. All vaccines in current use depend on growth of virus and most of the non-replicating (inactivated) vaccines involve wild type viruses known to cause poliomyelitis. The attenuated vaccine strains involved in the eradication programme have been used to develop new inactivated vaccines as production is thought safer. However it is known that the Sabin vaccine strains are genetically unstable and can revert to a virulent transmissible form. A possible solution to the need for virus growth would be to generate empty viral capsids by recombinant technology, but hitherto such particles are so unstable as to be unusable. We report here the genetic manipulation of the virus to generate stable empty capsids for all three serotypes. The particles are shown to be extremely stable and to generate high levels of protective antibodies in animal models.

There is a need for safe production of polio vaccines as eradication is approached. Empty capsids in a native conformation are produced by poliovirus and other picornaviruses seemingly as a necessary part of the assembly process, possibly to provide a reservoir of subunits in a form that is resistant to cellular pathways that target unfolded or hydrophobic motifs for proteolytic degradation. Normally they are not very stable prior to genome encapsidation but more stable forms, if they existed, could potentially be useful as vaccines. Genetic variants that increase empty capsid stability have been identified and by artificially combining several in one sequence the evolutionary constraints have been bypassed, with the resulting stable empty capsids representing essentially dead-end products. They induce antibody efficiently and are stable on storage. Empty capsids can be produced by recombinant expression which, if it were efficient enough, could provide a source of immunogenic particles suitable for use as vaccines without the need for live virus at any stage of production. This would be ideal for a post-eradication world.

Cross-sectional Serologic Assessment of Immunity to Poliovirus in Differential Risk Areas of India: India Seroprevalence Survey - 2014

OBJECTIVE

To assess the seroprevalence against all three poliovirus serotypes in traditional high risk areas in Bihar, lowest routine immunization coverage areas in Madhya Pradesh and migrant population living in Mumbai urban slums.

DESIGN

Cross-sectional Survey.

SETTING

Subjects selected by house to house visit (community based) and transported to government health facilities for further study procedures.

PARTICIPANTS

1137 randomly selected healthy infants 6-11 months of age residing in the selected high-risk areas.

METHODS

Serum samples from the study site were shipped to Enterovirus Research Centre (ERC), Mumbai to determine the neutralizing antibodies against all three poliovirus serotypes. Children with a reciprocal antibody titer ≥1:8 were considered seropositive to the specific poliovirus.

RESULTS

Overall, seroprevalence in all the three study areas was 98%, 98% and 91% against poliovirus type-1, type-2 and type-3, respectively. Bihar had a seroprevalence of 99%, 99% and 92% against type-1, type-2 and type-3 respectively. Corresponding figures for Madhya Pradesh and Mumbai were 98%, 99% and 88% and 98%, 97% and 94%, respectively.

CONCLUSION

The study found high seroprevalence against all three poliovirus types not only in the traditional high-risk areas for polio in India, but even in the areas known to have low routine immunization coverage and among the migratory clusters living in Mumbai urban slums. Type-2 seroprevalence was found to be high. These findings are reassuring against the threat of emergence of circulating vaccine derived polioviruses (cVDPVs) in the country subsequent to switch from trivalent oral polio vaccine to bivalent oral polio vaccine in the routine immunization schedule from April 2016.

[Complete Genome Characterization of Vaccine-derived Polioviruses Isolated in Yunnan,China]

To explore the genomic characterization of 4vaccine-derived poliovirus(VDPV)strains isolated from 2acute flaccid paralysis(AFP)cases in Yunnan Province in 2010 and 2012,respectively,the complete genome sequences of the 4strains were determined. Sequence analysis revealed that the complete genome length of the type Ⅱ and type Ⅰ VDPV was 7439nt and 7441 nt, respectively. Nucleotide and amino acid sequence similarities of type II VDPV were 95.4% and 97.7%,respectively,and type I VDPV were93.9% and 97.9%,respectively as compared with those of Sabin strains. Nucleotide substitutions were found at two important attenuation sites (nt 481 and nt in type Ⅱ VDPV, and three important attenuation sites(nt480,nt2795 and nt6203)in type I VDPV. Type 2 and type 1VDPV strains had 1.0% and2.3% divergence with Sabin strains, respectively. Similarity plot analysis showed multiple recombination events in the genome of the 4strains,which showed that the recombination was common and complex. Analysis of the characteristics of VDPVs on molecular level could provide valuable information on evolutionary dynamics and lay foundation for developing scientific and feasible strategy to control VDPV.

Contribution of Environmental Surveillance Toward Interruption of Poliovirus Transmission in Nigeria, 2012-2015

BACKGROUND

Cases of paralysis caused by poliovirus have decreased by >99% since the 1988 World Health Assembly's resolution to eradicate polio. The World Health Organization identified environmental surveillance (ES) of poliovirus in the poliomyelitis eradication strategic plan as an activity that can complement acute flaccid paralysis (AFP) surveillance. This article summarizes key public health interventions that followed the isolation of polioviruses from ES between 2012 and 2015.

METHODS

The grap method was used to collect 1.75 L of raw flowing sewage every 2-4 weeks. Once collected, samples were shipped at 4 °C to a polio laboratory for concentration. ES data were then used to guide program implementation.

RESULTS

From 2012 to 2015, ES reported 97 circulating vaccine-derived polioviruses (cVDPV2) and 14 wild polioviruses. In 2014 alone, 54 cVDPV type 2 cases and 1 WPV type 1 case were reported. In Sokoto State, 58 cases of AFP were found from a search of 9426 households. A total of 2 252 059 inactivated polio vaccine and 2 460 124 oral polio vaccine doses were administered to children aged <5 year in Borno and Yobe states.

CONCLUSIONS

This article is among the first from Africa that relates ES findings to key public health interventions (mass immunization campaigns, inactivated polio vaccine introduction, and strengthening of AFP surveillance) that have contributed to the interruption of poliovirus transmission in Nigeria.

Crippling Violence: Conflict and Incident Polio in Afghanistan

BACKGROUND

Designing effective public health campaigns in areas of armed conflict requires a nuanced understanding of how violence impacts the epidemiology of the disease in question.

METHODS

We examine the geographical relationship between violence (represented by the location of detonated Improvised Explosive Devices) and polio incidence by generating maps of IEDs and polio incidence during 2010, and by comparing the mean number of IED detonations in polio high-risk districts with non polio high-risk districts during 2004-2009.

RESULTS

We demonstrate a geographic relationship between IED violence and incident polio. Districts that have high-risk for polio have highly statistically significantly greater mean numbers of IEDs than non polio high-risk districts (p-values 0.0010-0.0404).

CONCLUSIONS

The geographic relationship between armed conflict and polio incidence provides valuable insights as to how to plan a vaccination campaign in violent contexts, and allows us to anticipate incident polio in the regions of armed conflict. Such information permits vaccination planners to engage interested armed combatants to co-develop strategies to mitigate the effects of violence on polio.

Poliovirus Laboratory Based Surveillance: An Overview

World Health Assembly (WHA) in 1988 encouraged the member states to launch Global Polio Eradication Initiative (GPEI) (resolution WHA41.28) against "the Crippler" called poliovirus, through strong routine immunization program and intensified surveillance systems. Since its launch, global incidence of poliomyelitis has been reduced by more than 99 % and the disease squeezed to only three endemic countries (Afghanistan, Pakistan, and Nigeria) out of 125. Today, poliomyelitis is on the verge of eradication, and their etiological agents, the three poliovirus serotypes, are on the brink of extinction from the natural environment. The last case of poliomyelitis due to wild type 2 strain occurred in 1999 in Uttar Pradesh, India whereas the last paralytic case due to wild poliovirus type 3 (WPV3) was seen in November, 2012 in Yobe, Nigeria. Despite this progress, undetected circulation cannot fully rule out the eradication as most of the poliovirus infections are entirely subclinical; hence sophisticated environmental surveillance is needed to ensure the complete eradication of virus. Moreover, the vaccine virus in under-immunized communities can sometimes revert and attain wild type characteristics posing a big challenge to the program.

New Strains Intended for the Production of Inactivated Polio Vaccine at Low-Containment After Eradication

Poliomyelitis has nearly been eradicated through the efforts of the World Health Organization's Global Eradication Initiative raising questions on containment of the virus after it has been eliminated in the wild. Most manufacture of inactivated polio vaccines currently requires the growth of large amounts of highly virulent poliovirus, and release from a production facility after eradication could be disastrous; WHO have therefore recommended the use of the attenuated Sabin strains for production as a safer option although it is recognised that they can revert to a transmissible paralytic form. We have exploited the understanding of the molecular virology of the Sabin vaccine strains to design viruses that are extremely genetically stable and hyperattenuated. The viruses are based on the type 3 Sabin vaccine strain and have been genetically modified in domain V of the 5' non-coding region by changing base pairs to produce a cassette into which capsid regions of other serotypes have been introduced. The viruses give satisfactory yields of antigenically and immunogenically correct viruses in culture, are without measurable neurovirulence and fail to infect non-human primates under conditions where the Sabin strains will do so.

[Investigation of a Patient with Pre-vaccine-derived Poliovirus in Shandong Province, China]

To analyze the genetic characteristics of a polio-I highly variant vaccine recombinant virus in Shandong Province (China) in 2011 and to identify isolates from healthy contacts, two stool specimens from one patient with acute flaccid paralysis (AFP) and 40 stool specimens from his contacts were collected for virus isolation. The complete genome of poliovirus and VP1 coding region of the non-polio enterovirus were sequenced. Homologous comparison and phylogenetic analyses based on VP1 sequences were undertaken among coxsackievirus (CV) B1, CV-B3 isolates, and those in GenBank. One poliovirus (P1/11186), CV-A4 and CV-A8 were isolated from the AFP patient; one CV-A2, Echovirus 3 (E-3), E-12 and E-14, ten CV-B1, and five CV-B3 strains were isolated from his contacts. These results led us to believe that there may be a human enterovirus epidemic in this area, and that surveillance must be enhanced. P1/11186 was a type-1 vaccine-related poliovirus; it combined with type-2 and type-3 polioviruses in 2A and 3A regions, respectively. There were 25 nucleotide mutations with 9 amino-acid alterations in the entire genome. There were 8 nucleotide mutations with 5 amino-acid alterations in the VP1 region compared with the corresponding Sabin strains. Homology analyses suggested that the ten CV-B1 isolates had 97.0%-100% nucleotide and 98.9%-100% amino-acid identities with each other, as well as 92.6%-100% nucleotide and 99.2%-100% amino-acid identities among the five CV-B3 isolates. Phylogenetic analyses on the complete sequences of VP1 among CV-B1 and CV-B3 isolates showed that Shandong strains, together with strains from other provinces in China, had a close relationship and belonged to the same group.

Twenty-Eight Years of Poliovirus Replication in an Immunodeficient Individual: Impact on the Global Polio Eradication Initiative

There are currently huge efforts by the World Health Organization and partners to complete global polio eradication. With the significant decline in poliomyelitis cases due to wild poliovirus in recent years, rare cases related to the use of live-attenuated oral polio vaccine assume greater importance. Poliovirus strains in the oral vaccine are known to quickly revert to neurovirulent phenotype following replication in humans after immunisation. These strains can transmit from person to person leading to poliomyelitis outbreaks and can replicate for long periods of time in immunodeficient individuals leading to paralysis or chronic infection, with currently no effective treatment to stop excretion from these patients. Here, we describe an individual who has been excreting type 2 vaccine-derived poliovirus for twenty eight years as estimated by the molecular clock established with VP1 capsid gene nucleotide sequences of serial isolates. This represents by far the longest period of excretion described from such a patient who is the only identified individual known to be excreting highly evolved vaccine-derived poliovirus at present. Using a range of in vivo and in vitro assays we show that the viruses are very virulent, antigenically drifted and excreted at high titre suggesting that such chronic excreters pose an obvious risk to the eradication programme. Our results in virus neutralization assays with human sera and immunisation-challenge experiments using transgenic mice expressing the human poliovirus receptor indicate that while maintaining high immunisation coverage will likely confer protection against paralytic disease caused by these viruses, significant changes in immunisation strategies might be required to effectively stop their occurrence and potential widespread transmission. Eventually, new stable live-attenuated polio vaccines with no risk of reversion might be required to respond to any poliovirus isolation in the post-eradication era.

The global polio eradication initiative is the most ambitious and complex public health programme directed at a single disease in history with a projected cost of $16.5 billion. Of the three serotypes types 2 and 3 appear to have been eradicated in the wild and type 1 is mostly confined to a region of Pakistan and Afghanistan. There is a real probability of total eradication in the near future. The main vaccine used is a live attenuated virus, and our paper concerns one of the most intractable significant implications that this has for the polio endgame. We describe virological studies of a patient deficient in humoral immunity who has been excreting type 2 vaccine-derived poliovirus for 28 years. Our results show that the viruses are excreted at high titres, extremely virulent and antigenically drifted and raise questions about how the population may best be protected from them, particularly in the light of possible changes in vaccine production which are being encouraged to increase capability and reduce costs. The study has implications for the ecology of poliovirus in the human gut and highlights the risks that such vaccine-derived isolates pose for polio re-emergence in the post-eradication era.

Modeling options to manage type 1 wild poliovirus imported into Israel in 2013

BACKGROUND

After 25 years without poliomyelitis cases caused by circulating wild poliovirus (WPV) in Israel, sewage sampling detected WPV type 1 (WPV1) in April 2013, despite high vaccination coverage with only inactivated poliovirus vaccine (IPV) since 2005.

METHODS

We used a differential equation-based model to simulate the dynamics of poliovirus transmission and population immunity in Israel due to past exposure to WPV and use of oral poliovirus vaccine (OPV) in addition to IPV. We explored the influences of various immunization options to stop imported WPV1 circulation in Israel.

RESULTS

We successfully modeled the potential for WPVs to circulate without detected cases in Israel. Maintaining a sequential IPV/OPV schedule instead of switching to an IPV-only schedule in 2005 would have kept population immunity high enough in Israel to prevent WPV1 circulation. The Israeli response to WPV1 detection prevented paralytic cases; a more rapid response might have interrupted transmission more quickly.

CONCLUSIONS

IPV-based protection alone might not provide sufficient population immunity to prevent poliovirus transmission after an importation. As countries transition to IPV in immunization schedules, they may need to actively manage population immunity and consider continued use of OPV, to avoid the potential circulation of imported live polioviruses before globally coordinated cessation of OPV use.

Lot-to-Lot Consistency of a Combined Hexavalent Diptheria-Tentanus-Acellular-Pertussis, Hepatitis B, Inactivated Polio and Haemophilus b Conjugate Vaccine, Adminstered to Healthy Chilean Infants at 2, 4 and 6 Months of Age

OBJECTIVES

To assess the safety, immunogenicity and lot consistency of a liquid hexavalent combined vaccine (DTaP-IPV-PRP approximately T-HBs, HEXAVAC) (Sanofi-Pasteur MSD, France) administered to infants at two, four and six months of age.

METHODS

A total of 1028 infants were vaccinated with one of three vaccine lots, in a randomized, double-blind fashion. Equivalence testing was used to compare post-vaccination seroprotection/seroconversion rates and geometric mean titers (GMTs) for each antigen between the three lots. Blood samples were drawn before vaccination and one month after the third dose. Local and systemic adverse events were monitored for three days following each injection.

RESULTS

Equivalence between lots was demonstrated for all antigens, on post-dose 3 seroprotection/seroconversion rates and GMTs. Reported rates of local and systemic adverse events tended to increase with subsequent doses. Altogether, 11.8% of the infants reported at least one adverse local event (mainly redness and induration/swelling) after the first dose and 36.1% after the third dose. Systemic adverse events (mainly irritability and fever) were reported by 39.2% of the infants after the first dose and by 57.5% after the third one.

CONCLUSION

Three separate lots of the liquid hexavalent combined vaccine induced consistently protective antibody responses against all antigens. These results and the well established clinical tolerability of this combined vaccine make it suitable for primary immunization of infants at two, four and six months of age.

Australia's polio risk

Australia, like all polio-free countries and regions, remains at risk of a wild poliovirus importation until polio is eradicated globally. The most probable route of importation will be through a traveller arriving in Australia either by air or sea from a polio-endemic or re-infected country. While the overall risk of an imported wild poliovirus infection leading to transmission within Australia is assessed as being low, some areas of the country have been identified as at increased risk. Local areas with relatively high arrivals from polio endemic countries, areas of low vaccination coverage and the potential for transmission to occur when these 2 factors are combined, were identified by this review as Australia's main polio risk. The risk of an importation event leading to locally acquired cases is mitigated by generally high polio vaccination coverage in Australia. This high coverage extends to residents of the Torres Strait Islands who are in close proximity to Papua New Guinea, a country identified as at high risk of poliovirus transmission should an importation occur. In 2012, all states and territories had vaccination coverage of greater than 90% at 1 year of age and all exceeded 93% at 2 years of age. Population immunity to wild poliovirus type 1, which remains the major cause of paralysis globally, has been estimated at 82%. This is sufficient to prevent outbreaks of this type in Australia. Of the 211 eligible non-polio acute flaccid paralysis (AFP) cases classified between 2008 and 2011, 91% (193) were vaccinated against polio at least once. High quality surveillance for AFP, which is supplemented by sentinel enterovirus and environmental surveillance activities, gives confidence that an imported case would be detected and appropriate public health action would ensue.

A combined diphtheria, tetanus, five-component acellular pertussis, poliovirus andHaemophilus influenzaetype b vaccine

Ideally, combination vaccines should not only be safe and effective, but also integrate smoothly into the vaccination schedule and provide advantages over the use of separately administered vaccines. Pentaceltrade mark (Sanofi Pasteur Ltd., Toronto, Canada), a combination vaccine first licensed in Canada and subsequently in other countries, is immunogenic against diphtheria, tetanus, pertussis, polio and Haemophilus influenzae type b when administered at 2, 4, 6 and 15-18 months of age. In published studies, the safety, immunogenicity and effectiveness of this combination vaccine were comparable with those of separately administered vaccines, with the advantage of a simplified dosing schedule.

Developmental immunology and vaccines: Immune responses to vaccines in premature infants

A comparatively small number of studies have assessed the safety, immunogenicity, efficacy and duration of immune responses in preterm infants compared with term infants for routinely recommended childhood immunizations.

ELISA as a possible alternative to the neutralization test for evaluating the immune response to poliovirus vaccines

This review describes several enzyme-linked immunosorbent assay (ELISA) techniques proposed to replace the neutralization test for detecting neutralization-relevant antibodies to polioviruses in recipients of inactivated poliovirus vaccine and oral poliovirus vaccine, and for seroepidemiologic studies. Comparisons of results from ELISA and the neutralization test suggest that ELISA variants, based on the principle of blocking or binding inhibition that emulate the neutralization test, might offer an alternative to the neutralization test. However, to replace the neutralization test with ELISA would first require extensive studies with very large numbers of serum samples, including sera having low titers of neutralizing antibodies, in order to obtain reliable and statistically sound validation.

Multiple independent emergences of type 2 vaccine-derived polioviruses during a large outbreak in northern Nigeria

Since 2005, a large poliomyelitis outbreak associated with type 2 circulating vaccine-derived poliovirus (cVDPV2) has occurred in northern Nigeria, where immunization coverage with trivalent oral poliovirus vaccine (tOPV) has been low. Phylogenetic analysis of P1/capsid region sequences of isolates from each of the 403 cases reported in 2005 to 2011 resolved the outbreak into 23 independent type 2 vaccine-derived poliovirus (VDPV2) emergences, at least 7 of which established circulating lineage groups. Virus from one emergence (lineage group 2005-8; 361 isolates) was estimated to have circulated for over 6 years. The population of the major cVDPV2 lineage group expanded rapidly in early 2009, fell sharply after two tOPV rounds in mid-2009, and gradually expanded again through 2011. The two major determinants of attenuation of the Sabin 2 oral poliovirus vaccine strain (A481 in the 5'-untranslated region [5'-UTR] and VP1-Ile143) had been replaced in all VDPV2 isolates; most A481 5'-UTR replacements occurred by recombination with other enteroviruses. cVDPV2 isolates representing different lineage groups had biological properties indistinguishable from those of wild polioviruses, including efficient growth in neuron-derived HEK293 cells, the capacity to cause paralytic disease in both humans and PVR-Tg21 transgenic mice, loss of the temperature-sensitive phenotype, and the capacity for sustained person-to-person transmission. We estimate from the poliomyelitis case count and the paralytic case-to-infection ratio for type 2 wild poliovirus infections that ∼700,000 cVDPV2 infections have occurred during the outbreak. The detection of multiple concurrent cVDPV2 outbreaks in northern Nigeria highlights the risks of cVDPV emergence accompanying tOPV use at low rates of coverage in developing countries.

[History of development of the live poliomyelitis vaccine from Sabin attenuated strains in 1959 and idea of poliomyelitis eradication]

In 1958 Poliomyelitis Institute in Moscow and Institute of Experimental Medicine in St. Petersburg received from A. Sabin the attenuated strains of poliomyelitis virus. The characteristics of the strains were thoroughly studied by A. A. Smorodintsev and coworkers. They found that the virulence of the strains fluctuated slightly in 10 consecutive passages through the intestine of the non-immune children. A part of the Sabin material was used by A. A. Smorodintsev and M. P. Chumakov in the beginning of 1959 for immunizing approximately 40000 children in Estonia, Lithuania, and Latvia. Epidemic poliomyelitis rate in these republics decreased from approximately 1000 cases yearly before vaccination to less than 20 in the third quarter of 1959. This was a convincing proof of the efficacy and safety of the vaccine from the attenuated Sabin strains. In 1959, according to A. Sabin's recommendation, a technology of live vaccine production was developed at the Poliomyelitis Institute, and several experimental lots of vaccine were prepared. In the second part of 1959, 13.5 million children in USSR were immunized. The epidemic poliomyelitis rate decreased 3-5 times in different regions without paralytic cases, which could be attributed to the vaccination. These results were the final proof of high efficiency and safety of live poliomyelitis vaccine from the attenuated Sabin strains. Based on these results, A. Sabin and M. P. Chumakov suggested in 1960 the idea of poliomyelitis eradication using mass immunization of children with live vaccine. 72 million persons up to 20 years old were vaccinated in USSR in 1960 with a 5 times drop in the paralytic rate. 50-year-long use of live vaccine results in poliomyelitis eradication in almost all countries worldwide. More than 10 million children were rescued from the death and palsy. Poliomyelitis eradication in a few countries where it still exists depends not on medical services but is defined by the attitude of their leaders to fight against poliomyelitis. In some developing countries the vaccination data are falsified, thereby threatening the polio epidemics reappearance and the virus spreading to other countries. Methods must be developed for detection and dealing with extremely rare persistent virus carriers. Because of all these constraints the outcome of poliomyelitis eradication at present is uncertain and vaccination must be continued. The world has become poliovaccine dependent.

Status of immunity for vaccine--preventable diseases in children after hematopoietic stem cells transplantation

INTRODUCTION

patients treated with hematopoietic stem cell transplantation (HSCT) lose immune memory accumulated through a lifetime. They are at increased risk of developing infections with microorganisms such as Haemophilus influenza, Streptococcus pneumoniae and others for which vaccines are available. Therefore, all patients after HSCT should be routinely revaccinated. Systemic reimmunization after HSCT is a relatively neglected area especially in countries which have not national recommendations and there is lack of systemic regulations in health care system.

OBJECTIVE

the rate of immunization before transplantation and the persistence of vaccine-specific antibodies after HSCT was assessed.

STUDY DESIGN

a group of38 children after stem cell transplantation (19 autologous, 19 allogeneic) was studied.

RESULTS

only a few patients completed standard vaccination protocol before HSCT. At the median time of 29 (range: 6-67) months after autologous and 13 (range: 8-33) months after allogeneic HSCT, when the revaccination was commenced, the majority of children had concentration of antibody lower than the minimum protective thresholds. That was 82% for tetanus, 71% for Hib and varicella, 46% for HBV and 38% for diphtheria.

CONCLUSIONS

all HSCT recipients should be routinely revaccinated to stimulate the immunity to the vaccine-preventable diseases.

Resistance of polio to its eradication in Pakistan

BACKGROUND

This study is based on EPI (Expanded Program on Immunization) immunization surveys and surveillance of polio, its challenges in immunization and the way forward to overcome these challenges.

METHODS

Several Government documents, survey reports and unpublished program documents were studied and online search was made to find information on EPI Pakistan. SPSS 16 and Microsoft Excel 2007 were used for the statistical analysis.

RESULTS

Immunization against polio is higher in urban areas as compared to rural areas. Marked variation in vaccination has been observed in different provinces of Pakistan in the last decade. Secondly 10-20% of the children who have received their first dose of trivalent polio vaccine were deprived of their 2nd and 3rd dose because of poor performance of EPI and Lack of information about immunization.

CONCLUSION

In spite of numerous successes, such as the addition of new vaccines and raising immunization to over 100% in some areas, EPI is still struggling to reach its polio eradication goals. Inadequate service delivery, lack of information about immunization and limited number of vaccinators were found to be the key reason for poor performance of immunization and for large number of cases reported each year due to the deficiency of second and third booster dose.

Immunogenicity and safety of fully liquid DTaP₅-IPV-Hib compared with DTaP₃-IPV/Hib when both coadministered with a heptavalent pneumococcal conjugate vaccine (PCV7) at 2, 3, 4, and 12 to 18 months of age: a phase III, single-blind, randomised, controlled, multicentre study

This study compared immunogenicity and safety of DTaP(5)-IPV-Hib to DTaP(3)-IPV/Hib coadministered with PCV7 at 2, 3, and 4 months (primary series) and a fourth-dose booster at 12-18 months of age. Seroprotection rates for DTaP(5)-IPV-Hib were high (noninferior to DTaP(3)-IPV/Hib for the primary series) for antigens common to both vaccines and PCV7 antigens. Geometric mean concentration (GMC) for Hib antibodies were higher in the DTaP(5)-IPV-Hib group than the DTaP(3)-IPV/Hib group after the primary series and booster dose; GMCs or titers for other antigens were generally similar between groups after the primary series and booster dose. Safety profiles were similar between groups.

Knowledge attitude practice study on pulse polio immunization in Mangalore, Dakshina Kannada district, Karnataka

Government of India launched PPI in 1995 to eradicate polio by the end of 2000. Despite this 733 cases were reported last year alone. There is a need to understand the reason behind high number of cases being reported even after so many years of programme implementation. This study was therefore conducted to assess knowledge of people about polio and PPI, their attitude and practice towards PPI. This cross sectional study was done in Mangalore city of Karnataka. Only houses having under five children were taken for the study. Data was collected by interviewing any adult member of the household using a pretested questionnaire. Out of 100 participants 99 were literates but only 11 knew the correct mode of transmission of polio. Twenty seven had misconception that polio is a curable disease. Only 40 participants knew that polio drops can be given to children even with mild illnesses. Few (2%) participants felt that PPI causes vaccine overdose and 8 participants thought PPI to be a substitute for routine immunization. This study identified few important misconceptions associated with polio and PPI. This needs to be addressed by large scale awareness campaigns in order to eradicate polio in the near future.

Immunogenicity and safety of combined adsorbed low-dose diphtheria, tetanus and inactivated poliovirus vaccine (REVAXIS (®)) versus combined diphtheria, tetanus and inactivated poliovirus vaccine (DT Polio (®)) given as a booster dose at 6 years of age

This randomized, comparative, phase-IIIb study conducted in France aimed to demonstrate whether seroprotection against diphtheria, tetanus and poliomyelitis 1 month after a single dose of REVAXIS (low-dose diphtheria) is non-inferior to seroprotection 1 month after a single dose of DT Polio (standard-dose diphtheria), both vaccines being given as a second booster to healthy children at 6 years of age. Children were randomly assigned to receive a single intramuscular dose of REVAXIS or DT Polio. Primary endpoints were the 1-month post-booster seroprotection rates for diphtheria, tetanus and poliovirus type-1, -2 and -3 antigens. Secondary endpoints were immunogenicity and safety observations. Of 788 children screened, 760 were randomized: REVAXIS group, 384 children; DT Polio group, 376 children. No relevant difference in demographic characteristics at baseline was observed between REVAXIS and DT Polio groups. Non-inferiority of REVAXIS compared with DT Polio for seroprotection was demonstrated against diphtheria (respectively 98.6% and 99.3%), tetanus (respectively 99.6% and 100%), and poliovirus antigens (100% for each types in both groups). No allergic reactions to REVAXIS were reported. A benefit/risk ratio in favor of REVAXIS was suggested by the trend towards a better tolerability of REVAXIS compared with DT Polio regarding the rate of severe solicited injection-site reactions. The results support the use of REVAXIS as a booster at 6 years of age in infants who previously received a three-dose primary series within the first 6 months of life and a first booster including diphtheria, tetanus and poliovirus vaccine(s) given before 2 years of age.

Immunity status of adults and children against poliomyelitis virus type 1 strains CHAT and Sabin (LSc-2ab) in Germany

BACKGROUND

In October 2007, the working group CEN/TC 216 of the European Committee for standardisation suggested that the Sabin oral poliovirus vaccine type 1 strain (LSc-2ab) presently used for virucidal tests should be replaced by another attenuated vaccine poliovirus type 1 strain, CHAT. Both strains were historically used as oral vaccines, but the Sabin type 1 strain was acknowledged to be more attenuated. In Germany, vaccination against poliomyelitis was introduced in 1962 using the oral polio vaccine (OPV) containing Sabin strain LSc-2ab. The vaccination schedule was changed from OPV to an inactivated polio vaccine (IPV) containing wild polio virus type 1 strain Mahoney in 1998. In the present study, we assessed potential differences in neutralising antibody titres to Sabin and CHAT in persons with a history of either OPV, IPV, or OPV with IPV booster.

METHODS

Neutralisation poliovirus antibodies against CHAT and Sabin 1 were measured in sera of 41 adults vaccinated with OPV. Additionally, sera from 28 children less than 10 years of age and immunised with IPV only were analysed. The neutralisation assay against poliovirus was performed according to WHO guidelines.

RESULTS

The neutralisation activity against CHAT in adults with OPV vaccination history was significantly lower than against Sabin poliovirus type 1 strains (Wilcoxon signed-rank test P < 0.025). In eight sera, the antibody titres measured against CHAT were less than 8, although the titre against Sabin 1 varied between 8 and 64. Following IPV booster, anti-CHAT antibodies increased rapidly in sera of CHAT-negative adults with OPV history. Sera from children with IPV history neutralised CHAT and Sabin 1 strains equally.

CONCLUSION

The lack of neutralising antibodies against the CHAT strain in persons vaccinated with OPV might be associated with an increased risk of reinfection with the CHAT polio virus type 1, and this implies a putative risk of transmission of the virus to polio-free communities. We strongly suggest that laboratory workers who were immunised with OPV receive a booster vaccination with IPV before handling CHAT in the laboratory.

[Evaluation of real time fluorescent quantitative reverse transcription polymerase chain reaction for detection of poliovirus]

OBJECTIVE

Application of Real Time Fluorescent quantitative reverse transcription polymerase chani reaction (rRT-PCR)to poliovirus identification in Chinese Poliomyelitis Laboratory Network and evaluation of the assay.

METHODS

According to Real-time RT-PCR recommended by WHO and developed by USA Centers for Disease Control and Prevention, 10 poliovirus isolates from laboratories of Chinese poliomyelitis network were tested for intratypic differentiation (ITD) and vaccine derived polioviruses (VDPVs) screening. The results of Real-time RT-PCR for 10 isolates were compared with those of VP, region sequencing.

RESULT

The Real-time RT-PCR results for 10 isolates did not completely consist with those of VP1 region sequencing. 5 Pre-VDPVs can not be identified by Real-time RT-PCR and type IVDPV from Shanxi province in 2009 was missed by the assay.

CONCLUSION

The Real-time RT-PCR retrospective and prospective researches for large scale of polioviruses well be conducted to determine if the assay is applicable to Chinese Poliomyelitis Laboratory Network.

[Analysis on vaccine-derived poliovirus found from acute flaccid paralysis cases and effectiveness for emergency response in Binzhou in 2007]

OBJECTIVE

To analyze VDPV found from acute flaccid paralysis cases and effectiveness for emergency response in Binzhou, Shandong in 2007.

METHODS

Outbreak investigation, rapid evaluation for oral poliomyelitis attenuate live vaccine (OPV) coverage rate, active searched for acute flaccid paralysis (AFP)cases, supervision for VDPV case, virology and serology surveillance, mopping-up of OPV were used for this emergency response to prevent the possible VDPV spread.

RESULTS

The case was reported from the AFP surveillance system. The poliovirus type I was isolated from stool specimen, which was identified as VDPV by gene sequencing. This AFP case was diagnosed as Guillain-barre syndrome (GBS) with 11 doses of OPV and normal self-immunity function test. The investigation results showed that the OPV coverage rates and the neutralization antibody to poliovirus type 1-3 were at high level among the local children, no similar VDPV was isolated from stools of healthy children around the case. The quality of AFP surveillance system was good, and had not found additional similar case in Bizhou city. Additional VDPV was not found in continuous stool specimen from this case. The case was diagnosed as VDPV infected vector but not VDPV case by the national and provincial expert group.

CONCLUSION

This VDPV was found in the area with high coverage rate OPV, There was no evidence for the VDPV circulation. The emergency response for the VDPV was rapid and effective. The VDPV surveillance and research related should be strengthened.

Evaluation of an acellular pertussis, diphtheria, tetanus, inactivated poliovirus, Hib-conjugate combined vaccine (Pentaxim) at 2, 4, and 6 months of age plus hepatitis B vaccine at birth, 2, and 6 months of age in infants in Thailand

The objective of this study was to evaluate the immunogenicity and safety of a pentavalent vaccine (Pentaxim) containing diphtheria, tetanus, acellular pertussis, inactivated poliovirus, and Hib polysaccharide-conjugate (DTaP-IPV//PRP-T) antigens, in Thai children. One hundred eighty-six infants who had received a hepatitis B vaccine at birth were given a pentavalent vaccine at 2, 4 and 6 months of age and a hepatitis B vaccine concomitantly at 2 and 6 months of age. Immunogenicity was high for each vaccine antigen. The study vaccine was well tolerated and side effects were few. After the third dose, 100% of subjects had an anti-PRP > or = 0.15 microg/ml and 96.5% > or = 1.0 microg/ml; the anti-PRP GMT was 9.53 microg/ml. Seroprotective rates for diphtheria and tetanus (> or = 0.01 IU/ml) were 99.4% and 100%, respectively, and 100% for all three poliovirus types (> or = 8 1/dil U). The vaccine response rates to pertussis antigens (a 4-fold increase in antibody titer were 94.1% for PT and 93.0% for FHA. The DTaP-IPV//PRP-T vaccine given at 2, 4 and 6 months of age concomitantly with a monovalent hepatitis B vaccine, was well tolerated and highly immunogenic for primary immunization of infants in Thailand.

Annual report of the Australian National Poliovirus Reference Laboratory, 2008

The Australian National Poliovirus Reference Laboratory (NPRL) is accredited by the World Health Organization (WHO) for the testing of stool specimens from cases of acute flaccid paralysis (AFP), a major clinical presentation of poliovirus infection. The NPRL, in collaboration with the Australian Paediatric Surveillance Unit, co-ordinates surveillance for cases of AFP in children in Australia, according to criteria recommended by the WHO. Clinical specimens are referred from AFP cases in children and suspected case of poliomyelitis in persons of any age. The WHO AFP surveillance performance indicator for a polio-free country such as Australia, is 1 non-polio AFP case per 100,000 children less than 15 years of age. In 2008, the Polio Expert Committee (PEC) classified 62 cases as non-polio AFP, or 1.51 non-polio AFP cases per 100,000 children aged less than 15 years. Poliovirus infection is confirmed by virus culture of stool specimens from AFP cases as other conditions that present with acute paralysis can mimic polio. While no poliovirus was reported in Australia from any source in 2008, the non-polio enteroviruses echovirus 25, coxsackievirus B2 and echovirus 11 were isolated from stool specimens of AFP cases. The last report of a wild poliovirus in Australia was due to an importation from Pakistan in 2007. With 4 countries remaining endemic for poliomyelitis--Afghanistan, India, Nigeria and Pakistan--and more than 1,600 confirmed cases of wild poliovirus infection in 18 countries in 2008, Australia continues to be at risk of further importation events.

Future of polio vaccines

Over the past half-century, global use of highly effective vaccines against poliomyelitis brought this disease to the brink of elimination. Mounting evidence supports the argument that a high level of population immunity must be maintained after wild poliovirus circulation is stopped to preserve a polio-free status worldwide. Shifting factors in the risk-benefit-cost equation favor the creation of new poliovirus vaccines for use in the foreseeable future. Genetically stable attenuated virus strains could be developed for an improved oral poliovirus vaccine, but proving their safety and efficacy would be impractical owing to the enormous size of the clinical trials required. Novel versions of inactivated poliovirus vaccine that could be used globally should be developed. An improved inactivated poliovirus vaccine must be efficacious, inexpensive, safe to manufacture and easy to administer. Combination products containing inactivated poliovirus vaccine and other protective antigens should become part of routine childhood immunizations around the world.

[Analysis on identification and genetic character of type I vaccine-derived poliovirus in Shanxi province in 2007]

OBJECTIVE

To describe the source of vaccine-derived poliovirus (VDPV) and the effect on local polio-free status, the VP1 coding region was sequenced and analyzed for type I VDPV in Shanxi province in 2007.

METHOD

The virus isolation was performed to double stool specimens from one case acute flaccid paralysis (AFP) patient. VP1 coding region of the isolated stain was sequenced and analyzed. The phylogenetic tree was constructed based on VP1 region sequence between Shanxi strains and other type I VDPVs.

RESULT

2 type I + II +III strains were isolated from double stool specimens from the AFP patient in Shanxi Province in 2007. VP1 sequencing of the two stains revealed > 1.0% divergence from the VP1 region of P I /Sabin vaccine strain. According to WHO criteria, the two stains were identified as type I vaccine-derived poliovirus (VDPV). Phylogenetic analysis based on VP1 coding sequence showed that the evolution distance of Shanxi type I VDPV was far away from other VDPVs detected in China. Moreover, no evidence supported the AFP patient as immunodeficiency patient. So Shanxi type I VDPVs were classified into ambiguous VDPV(aVDPV).

CONCLUSION

Considering the genetic character for Shanxi type I VDPV and the local OPV coverage, we highly suspected that an immunodeficiency patient in local area who long-term excreted VDPVs existed and resulted in the patient infection of VDPV in Shanxi in 2007. In the post era of polio eradication, the detection and management for the possible existing patient of long-term excretion VDPV should be strengthened.

Virus attenuation by genome-scale changes in codon pair bias

As a result of the redundancy of the genetic code, adjacent pairs of amino acids can be encoded by as many as 36 different pairs of synonymous codons. A species-specific "codon pair bias" provides that some synonymous codon pairs are used more or less frequently than statistically predicted. We synthesized de novo large DNA molecules using hundreds of over-or underrepresented synonymous codon pairs to encode the poliovirus capsid protein. Underrepresented codon pairs caused decreased rates of protein translation, and polioviruses containing such amino acid-independent changes were attenuated in mice. Polioviruses thus customized were used to immunize mice and provided protective immunity after challenge. This "death by a thousand cuts" strategy could be generally applicable to attenuating many kinds of viruses.

Recommendations of 2nd National Consultative Meeting of Indian Academy of Pediatrics (IAP) on polio eradication and improvement of routine immunization

JUSTIFICATION

Persistence of intense wild poliovirus (WPV) transmission, particularly type 3 in northern India necessitated the Indian Academy of Pediatrics (IAP) to convene a National Consultative Meeting to review its earlier recommendations on polio eradication and improvement of routine immunization.

PROCESS

More than thirty experts were invited and intense deliberations were held over two days to draw consensus statements on various issues related with polio eradication.

OBJECTIVES

To review the ongoing strategy, identify the existing challenges, and suggest modifications to the current strategy for eradication of poliomyelitis in India.

RECOMMENDATIONS

IAP reiterates its support to ongoing efforts on polio eradication but demand some flexibility in the strategy. The immediate challenges identified include persistent WPV type 1 transmission in Uttar Pradesh (UP) and Bihar, intense type 3 transmission also in UP and Bihar, and maintaining polio-free status of all other states. Circulating vaccine derived poliovirus (cVDPV), particularly type 2, was identified as a great future threat. Neglect of routine immunization (RI), poor efficacy of oral polio vaccine (OPV), operational issues, and inadequate uptake of OPV in the 2 endemic states are the main reasons of failure to interrupt transmission of WPV 1 and 3. However, for the first time in history the intensity of WPV 1 circulation is very low in western UP. IAP suggests that high-quality, uniform and consistent performance of supplementary immunization activities (SIAs) in all districts of western UP, particularly using mOPV1(monovalent OPV1) should be maintained to avoid reestablishment of circulation of type 1 poliovirus. A judicious mix of mOPV1 and mOPV3, given sequentially or even simultaneously (after validating the efficacies) will be necessary to address the upsurge of WPV3. Re-establishing routine immunization should be the foremost priority. IAP strongly recommends to Government of India (GOI) to take urgent measures to attain coverage of a minimum of 90% against all UIP antigens in all the states by the end of 2008. In view of the need to simultaneously raise immunity levels to protect against WPVs 1, 3 and cVDPV2, IPV may be given immediate consideration as an additional tool. IPV will be essential in the postWPVeradication phase; it can play a useful role even in the current WPV eradication phase. IAP urges the GOI to urgently sort out various issues associated with implementation of the proposal to use IPV. More transparency is needed on cases of vaccine associated paralytic poliomyelitis (VAPP). Further improvement in stool collection rates is also warranted to minimize the tally of compatible cases. IAP urges the social mobilization network to address the issues of waning interest and shifting focus and negative media coverage. Alternate tactics like reduced numbers of SIAs applied in the low transmission season, along with IPVDTP combination vaccine in RI can also be considered. IAP believes it will be risky to stop vaccination against poliomyelitis in postWPV eradication phase. The best option is to gradually introduce IPV starting now, so that a switch to IPV following high-performance national immunization days (NIDs) can be made to ensure sustained high immunity against all polioviruses, wild and vaccine derived. IAP requests the global polio eradication initiative (GPEI) to continue relevant research to inform on various aspects related to polio eradication, defined as zero incidence of any poliovirus infection. IAP also urges GOI to take immediate measures for improvement of environmental sanitation.

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

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

Primary vaccination of adults with reduced antigen-content diphtheria-tetanus-acellular pertussis or dTpa-inactivated poliovirus vaccines compared to diphtheria-tetanus-toxoid vaccines

OBJECTIVE

To evaluate immunogenicity and reactogenicity of primary vaccination with reduced-antigen-content diphtheria-tetanus-acellular pertussis (dTpa) or dTpa-inactivated poliovirus (dTpa-IPV) vaccine compared to diphtheria-tetanus-toxoid vaccines (Td) in adults > or = 40 years of age without diphtheria or tetanus vaccination for 20 years or with an unknown vaccination history.

RESEARCH DESIGN AND METHODS

Double-blind, randomized, controlled clinical trial. Primary vaccination with either three doses of dTpa, one dose of dTpa-IPV followed by two doses of Td, or three doses of Td vaccine (control) administered in a 0-1-6-month schedule.

MAIN OUTCOME MEASURES

Blood samples were collected before commencement and 1 month after each dose. Local and general symptoms were solicited for 15 days after each dose.

RESULTS

A total of 460 adults were enrolled, of whom over 48% did not have protective antibody concentrations against diphtheria and tetanus. One month after dose 3 > 99% had seroprotective anti-diphtheria and tetanus antibodies. Three doses were required to maximize anti-diphtheria seroprotection rates. A vaccine response to pertussis antigens was observed in > 92% of dTpa and dTpa-IPV recipients after dose 1. One month after dTpa-IPV, > 98.4% had seroprotective anti-polio titres. No statistically significant differences in local or general symptoms between groups were observed.

CONCLUSIONS

dTpa and dTpa-IPV can provide primary vaccination of adults. Combinations of dTpa or dTpa-IPV can be used to replace Td and provide booster vaccination against pertussis and polio simultaneously with diphtheria and tetanus, even in situations where the primary vaccination history is unknown.

Antibody persistence and booster vaccination during the second and fifth years of life in a cohort of children who were born prematurely

BACKGROUND

These studies assessed the immunogenicity and reactogenicity of booster vaccination with diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus-adsorbed conjugated Haemophilus influenzae type b (DTaP-HBV-IPV/Hib) at 18-20 months, and with DTaP during the fifth year of life in children who had been born prematurely (<37 weeks gestation).

METHODS

Open-label, parallel group studies in which preterm and full-term subjects primed with DTaP-HBV-IPV/Hib received booster vaccination with DTaP-HBV-IPV/Hib (Infanrix hexa) at 18-20 months and DTaP (Infanrix) at 4 years of age. Immunogenicity was assessed before and 1 month after DTaP-HBV-IPV/Hib dose and 1 month after DTaP administration. Local and general symptoms were recorded for 4 days, unsolicited symptoms for 31 days after each dose.

RESULTS

Before the second year booster, Hib, hepatitis-B, and polio type 3 seroprotection rates were higher in the full-term group (antipolyribosyl ribitol phosphate > or =0.15 microg/mL observed in 76.2%/83.6% preterm/full term respectively, anti-HBs > or =10 mIU/mL in 75.0%/80.6% respectively). One month after the DTaP-HBV-IPV/Hib booster, > or =98% in both groups were seroprotected/seropositive for all vaccine antigens, except hepatitis-B in preterms (seroprotection rate 91.6%). By the fifth year hepatitis-B seroprotection rates were 85.3%/70.5% (preterm/full term) in subjects who had previously responded to hepatitis-B vaccination, and seroprotection rates for polio and polyribosyl ribitol phosphate were >95%. No differences between groups were observed after the DTaP booster. Both booster doses were generally well tolerated with minimal differences observed between groups. Local symptoms occurred more frequently after the fifth vaccination at 4 years of age.

CONCLUSIONS

Despite trends for lower immune responses to some vaccine antigens in preterm subjects, these findings support undelayed primary and booster vaccination in infants and children born before term. Booster vaccinations with DTaP-HBV-IPV/Hib and DTaP were well tolerated in this susceptible group.

Epidemics to eradication: the modern history of poliomyelitis

Poliomyelitis has afflicted humankind since antiquity, and for nearly a century now, we have known the causative agent, poliovirus. This pathogen is an enterovirus that in recent history has been the source of a great deal of human suffering. Although comparatively small, its genome is packed with sufficient information to make it a formidable pathogen. In the last 20 years the Global Polio Eradication Initiative has proven successful in greatly diminishing the number of cases worldwide but has encountered obstacles in its path which have made halting the transmission of wild polioviruses a practical impossibility. As we begin to realize that a change in strategy may be crucial in achieving success in this venture, it is imperative that we critically evaluate what is known about the molecular biology of this pathogen and the intricacies of its interaction with its host so that in future attempts we may better equipped to more effectively combat this important human pathogen.