Cluster survey evaluation of coverage and risk factors for failure to be immunized during the 1995 National Immunization Days in Egypt

BACKGROUND: In 1995, Egypt continued to experience endemic wild poliovirus transmission despite achieving high routine immunization coverage with at least three doses of oral poliovirus vaccine (OPV3) and implementing National Immunization Days (NIDs) annually for several years. METHODS: Parents of 4188 children in 3216 households throughout Egypt were surveyed after the second round of the 1995 NIDs. RESULTS: Nationwide, 74% of children are estimated to have received both NID doses, 17% one NID dose, and 9% neither NID dose. Previously unimmunized (47%) or partially immunized (64%) children were less likely to receive two NID doses of OPV than were fully immunized children (76%) (P < 0.001). Other risk factors nationwide for failure to receive NID OPV included distance from residence to nearest NID site >10 minute walk (P < 0.001), not being informed about the NID at least one day in advance (P < 0.001), and residing in a household which does not watch television (P < 0.001). Based on these findings, subsequent NIDs in Egypt were modified to improve coverage, which has resulted in a marked decrease in the incidence of paralytic poliomyelitis in Egypt. CONCLUSIONS: In selected situations, surveys can provide important information that is useful for planning future NIDs.     

Interrupting the transmission of wild polioviruses with vaccines: immunological considerations.

In 1988 the World Health Assembly set the goal of global poliomyelitis eradication by the year 2000. Substantial progress has been made, and 143 countries reported no poliomyelitis cases associated with the wild virus in 1993. This article reviews the immunological considerations relevant to interrupting the transmission of wild polioviruses with vaccines. Although serum immunity prevents poliomyelitis in the individual, it is local immunity that is important in preventing the transmission of polioviruses in the community. Natural infection and vaccination with oral polioviruses vaccine (OPV) produce local immunity in the intestine and the nasopharynx in about 70-80% of individuals. In contrast, inactivated poliovirus vaccine (IPV) produces local intestinal immunity in only 20-30% of the individuals. With either vaccine, however, a substantial proportion of the immunized population can transmit the wild virus. Moreover, although serum immunity is long-lasting, limited data suggest that local immunity may not be as persistent. To interrupt the transmission of wild polioviruses efforts should be made to achieve and sustain high levels of poliovirus vaccine coverage. Recent outbreaks show that wild poliovirus poses a risk for unimmunized individuals, even when overall coverage levels are high. Delivery of poliovirus vaccine to hard-to-reach populations will be of increasing importance as countries progress toward the final stages of poliomyelitis eradication. The immunization status of persons from poliomyelitis-free countries should be updated prior to travel to poliomyelitis-endemic areas.     

我国现阶段维持无脊髓灰质炎状态面临的挑战和对策

中国通过使用口服脊髓灰质炎（脊灰）减毒活疫苗（OralPoliomyelitisAttenuatedLiveVaccine,OPV）、加强OPV常规免疫和开展补充免疫活动,以及加强急性弛缓性麻痹（AcuteFlaccidParalysis,AFP）病例监测,消灭脊灰已取得了重大进展。1994年报告最后1例本土脊灰野病毒（WildPoliovirus,WPV）病例,2000年包括中国在内的世界卫生组织西太平洋区实现无脊灰目标。随后中国实施了维持无脊灰策略和措施,但2011年新疆维吾尔自治区发生了输入脊灰疫情。在现阶段中国维持无脊灰状态面临的挑战包括：WPV输入风险很大,疫苗衍生脊灰病毒（Vaccine—derivedPoliovirus,VDPV）和疫苗相关麻痹型脊灰病例时有发生,常规免疫存在薄弱环节,脊灰疫苗免疫策略需要调整。为继续维持无脊灰状态,直至全球消灭脊灰,中国要大力加强OPV常规免疫,适时引入脊灰病毒灭活疫苗和调整脊灰疫苗免疫策略,保持高水平AFP病例监测质量,及时和有效地处置可能发生的WPV输入和VDPV循环事件,开展WPV、VDPV及其感染或潜在感染性材料的封存和安全处理。     

淮安市消灭脊髓灰质炎策略及效果分析

目的 评价淮安市消灭脊髓灰质炎防制策略效果。方法描述1956年以来脊髓灰质炎发病趋势；分析不同时期该病防制策略及发病特点。结果 随着脊灰疫苗的广泛使用和消灭脊灰活动的深入开展，淮安市脊灰发病率逐年下降，80年代脊灰发病开始得到有效控制，1995年以来已无确诊病例发生。主要防制策略是在常规免疫的基础上，开展强化免疫；加强免疫监测和急性弛缓性麻痹病例的监测。结论 淮安市已阻断了脊灰野病毒的传播；脊灰控制后，免疫策略应作相应调整，以控制疫苗相关病例的发生。     

Immunogenicity of oral poliomyelitis vaccine (OPV) against variants of wild poliovirus type 3

Serological investigations of three groups of children from the German Democratic Republic (GDR) and from Czechoslovakia who had different immunization histories against poliomyelitis indicated that the immunity induced by oral poliovaccine (OPV) is effective against both the wild poliovirus Saukett strain and a new wild variant of poliovirus type 3 that was isolated during an outbreak of poliomyelitis in Finland in 1984. There is therefore no obvious risk that individuals in the GDR or Czechoslovakia, most of whom have been immunized with OPV, are threatened by new wild poliovirus variants. These findings are of importance, especially in connection with WHO's initiative for the global eradication of poliomyelitis by the year 2000.     

Efficacy of oral poliovirus vaccine in rural communities of North Arcot District, India

The protective efficacy of three doses of oral poliovirus vaccine (OPV) was measured in children under five in the rural blocks of North Arcot District. In 1988, a sample survey of 7% of the total population of the district (population five million) was conducted to determine the immunization coverage with OPV and the incidence of paralytic poliomyelitis in under-fives in the previous 12 months, (n = 42,045). For every case of poliomyelitis, all children matched for exact age in months resident within the same block were taken as controls. Some 67 children had poliomyelitis (prevalence of lameness 1.59/1000, estimated annual incidence 2.57/1000 under-fives). Among cases and controls 24 and 42%, respectively, had received three doses of OPV, while 44 and 33% had received none. In a case-control analysis, the vaccine efficacy (VE) was 62% for all under-fives; for the 12-23 months age group it was 71.4%. For a vaccine with the potential of near 100% VE, this is disappointingly low. Obviously, not only the immunization coverage level, but also the VE should be enhanced if poliomyelitis is to be controlled in India. This may be achieved by a five-dose OPV schedule, annual OPV immunization campaigns in addition to the routine three-dose schedule or by using inactivated poliovirus vaccine of enhanced potency.     

Poliomyelitis control in Israel, the West Bank and Gaza Strip: changing strategies with the goal of eradication in an endemic area.

Israel has faced the challenge presented by epidemic poliomyelitis by using different immunization strategies. In the 1950s, inactivated poliovirus vaccine (IPV) helped to reduce the total burden of the disease, but cases continued to occur. Introduction of oral poliovirus vaccine (OPV) in mid-1961 had a dramatic effect in controlling an extensive epidemic of poliomyelitis; however, poliovirus activity and cases continued during the 1970s, and at a low level in the 1980s. A localized outbreak of 15 cases of poliomyelitis in 1988 occurred in an area using enhanced potency IPV (eIPV) only. This led to a revision of poliomyelitis immunization policy. The successful poliomyelitis control in the West Bank and the Gaza Strip using both OPV and IPV since 1978 shows the advantages of a combined approach. This programme was therefore adopted in modified form in the whole of Israel, the West Bank and Gaza. Since late 1988, no cases of poliomyelitis have occurred in any of these three areas, indicating the success of the combined poliomyelitis immunization programme. These experiences may be helpful to other countries, especially those where there is a danger of importation of wild poliovirus, and to prevent vaccine-associated disease. The combined approach provides an additional immunization model in the international effort to eradicate poliomyelitis.     

Vaccination against poliomyelitis in economically underdeveloped countries

Poliomyelitis lameness surveys in children of school age recently reported from Burma, Egypt, Ghana, and the Philippines have indicated an estimated, average annual endemic incidence of paralytic poliomyelitis similar to or higher than the overall average annual rate in the USA during the peak years in the prevaccine era. Contrary to oft-expressed dogma, high rates of paralytic poliomyelitis are occurring annually in regions with high infant mortality rates, continuing undernutrition, and absence of basic sanitary facilities. Recent data indicate that prolonged breast feeding does not impede the effectiveness of oral poliovirus vaccine (OPV). A high prevalence of nonpoliovirus enteric infections can modify, delay, and lower the frequency of seroconversion after OPV, but these effects are overcome by multiple doses. The problem of eliminating paralytic poliomyelitis from economically underdeveloped countries depends on administrative rather than immunological or epidemiological factors, although a specially concentrated effort is needed in countries where most of the cases occur during the first two years of life and where paralytic polioviruses are propagating throughout the year in a large proportion of the infant population. Under such circumstances, expanded routine infant immunization programmes, which include OPV but reach at best only 20-40% of the total infant population, who receive only one or a few doses of vaccines requiring multiple doses, cannot be expected to eliminate paralytic poliomyelitis as an important public health problem. Injections of multiple doses of quadruple vaccine (DPT + inactivated poliomyelitis vaccine) would not only greatly increase the cost of routine immunizations but would not achieve more or as much as feeding OPV at the time of the DPT injections. Mass administration of OPV each year on 2 days of the year 2 months apart, to all children under 2, 3, or 4 years of age (depending on the epidemiological situation), without reference to the number of OPV doses they may have had before, can be expected to yield optimum results in countries with small numbers of professional health personnel and many other year-round problems.     

Outbreak of poliomyelitis due to type 3 poliovirus,northern India, 1999-2000: injections a major contributing factor

BACKGROUND: A large outbreak of poliomyelitis due to poliovirus type 3 (P3) occurred in India in 1999. This raised concerns about oral poliovirus vaccine (OPV) effectiveness, particularly the type 3 component, in preventing clinical disease and offered an opportunity to describe the epidemiology of a P3 outbreak. METHODS: We reviewed data collected by the National Polio Surveillance Project to describe the outbreak and conducted a case-control study to determine risk factors for the development of paralytic poliomyelitis. The P3 cases with paralysis onset in 2000 were enrolled with four controls per case, matched for age and neighbourhood. RESULTS: Of 1126 virologically confirmed poliomyelitis cases reported in 1999, 719 (64%) were due to P3. We enrolled 48 (80%) of 60 cases and 175 matched controls. Age (30.6 months, cases versus 30.4 months, controls) and vaccination status (median 5.8 OPV doses, cases versus 6.1 OPV doses, controls) were similar among cases and controls. The only significant difference between the groups was the proportion that received any injection in the last 30 days prior to paralysis onset or the corresponding reference date for controls (35.4% versus 12.3%, adjusted odds ratio [OR] = 3.9, 95% CI: 1.8-12.5). CONCLUSIONS: Cases and controls had similar vaccination histories. The only significant risk factor for paralytic illness was having received any injection in the 30 days before onset. Our study confirms that injections administered during the poliovirus incubation period can provoke paralytic poliomyelitis. Injections in polio-endemic countries should only be indicated when other therapeutic options have failed or are not available.     

End phase challenges of poliomyelitis eradication programme realization

The progress of poliomyelitis eradication programme realization, the implementation schedule and strategies for the future, are summarised based on publications of the World Health Organisation. During the following two years wild poliovirus strains should be globally eradicated. This means that potentially in 2010 the global eradication of wild polioviruses will be certified. To eradicate poliomyelitis, cessation of the oral polio vaccine (OPV) is necessary, since the vaccine strains produce cases of vaccine-associated paralytic poliomyelitis (VAPP) and cases of poliomyelitis caused by circulating vaccine-derived poliovirus (cVDPV). However, the WHO plan to stop immunization with OPV and the immunization with inactivated polio vaccine (IPV) shortly after, is alarming in the present situation. The article describes the measures undertaken to prevent or minimise the risk of reintroduction of wild poliovirus strains, which is potentially associated with WHO plan of action.     

Vaccine-associated paralytic poliomyelitis: a retrospective cohort study of acute flaccid paralyses in Brazil

BACKGROUND: At the present time, in Brazil and other countries in the Americas, the only cases of paralytic poliomyelitis due to poliovirus are caused by vaccine strains. The recognition of possible determinants of vaccine-associated paralytic poliomyelitis (VAPP) by public health surveillance and immunization programmes is relevant to inform the debate on criteria for case definition and vaccination strategies. METHODS: A retrospective cohort study based on the cases of acute flaccid paralysis (AFP) reported to the Ministry of Health (MoH) was designed, with the objective of studying cases of VAPP in Brazil between 1989 and 1995. Clinical, laboratory and epidemiological data from 3656 acute flaccid paralysis (AFP) cases, 30 of them diagnosed as VAPP, were analysed. RESULTS: An 8.88 risk ratio of VAPP (95% CI : 4.37-18.03) was found when comparing individuals who received oral poliovirus vaccine (OPV) between 4 and 40 days before the onset of paralysis and individuals who did not receive the vaccine within this period. A risk of 1 case/2.39 million first doses and 1 case/13.03 million OPV doses administered was estimated for the general population. CONCLUSIONS: Cases of AFP who received OPV between 4 and 40 days before the onset of paralysis and had fever, a prodrome of gastrointestinal symptoms, history of first dose of OPV, isolation of vaccine poliovirus type 2, and young age deserve careful investigation, since they are at increased risk for the condition studied.     

The effect of immune globulin on the response to trivalent oral poliovirus and yellow fever vaccinations

To assess whether immune globulin may be administered concurrently with trivalent oral poliovirus vaccine (OPV) or yellow fever vaccine, antibody responses were studied in Peace Corps volunteers embarking for overseas duty in 1978. Of 200 volunteers who received OPV, 192 (96%) had pre-existing neutralizing antibody to at least 2 poliovirus types; of 160 yellow fever vaccinees, 24 (15%) had pre-existing 17D yellow fever antibody. Each volunteer received 5 ml of immune globulin, 0-7 days before, 3-5 days after, or 28-32 days after vaccination. This last group was designated the control group. Of the volunteers who received immune globulin 0-7 days before vaccination, 71% 72%, 49%, and 82% responded to poliovirus types 1, 2, and 3, and yellow fever, respectively (response was defined as a 4-fold or greater rise in serum neutralizing antibody titre between baseline (0-7 days before vaccination) and follow-up (15-40 days after vaccination)). These rates did not differ significantly from those in persons who received immune globulin 28-32 days after vaccination (61%, 60%, 51%, and 83%, respectively). Thus, among individuals who, for the most part, were immune to poliomyelitis but not to yellow fever, immune globulin did not decrease the antibody response to OPV or to yellow fever vaccine when given 0-7 days before vaccination.     

Outbreak of polio in adults--Namibia, 2006

After 10 years with no detected wild poliovirus (WPV) transmission in Namibia, an outbreak of poliomyelitis cases occurred in 2006. The outbreak was traced to importation from neighboring Angola of WPV type 1 (WPV1) that originated in India. As of October 2, 2006, a total of 19 cases of polio, with paralysis onset between early May and June 26, had been confirmed by isolation of WPV1 from stool specimens, primarily from young adult males; six of the patients died. This report describes outbreak investigation and response activities and provides an update on routine and supplemental immunization activities (SIAs) and acute flaccid paralysis (AFP) surveillance in Namibia.     

Impact of national immunization days on polio-related knowledge and practice of urban women in Bangladesh

Bangladesh began to hold National Immunization Days (NIDs) from 1995 as part of the country's goal to eradicate poliomyelitis by the turn of the century. The NIDs brought together government agencies, the media, voluntary organisations and individual volunteers in social mobilization and service delivery activities. This paper assesses the impact of the first two polio NIDs in terms of the immunization coverage and change in knowledge about the disease among women living in Dhaka city, the capital of the country. Data were collected through pre- and post-NID cross-sectional surveys in a sample of one area of Dhaka city which included slum and non-slum households. Knowledge data were collected from 525 women with at least one child aged less than five years. The oral polio vaccine (OPV) coverage during NIDs was obtained from 720 children. Knowledge of polio as a vaccine preventable disease increased after NIDs among both slum and non-slum women. The knowledge gap between the two groups was significantly reduced. Field workers, who regularly visit women at their homes to promote health and family planning services, were the main source of information for the slum women while television was cited as the most important source of information by non-slum women. The study revealed that 88% of children under five years received at least one dose of oral polio vaccine (OPV) during NIDs, and 67% received two stipulated doses with no significant differences between slum (65%) and non-slum (69%) groups. In addition, 68% of the children contacted during the NIDs were given vitamin A supplementation. The study suggests that strategies like NID can be effectively used to tap into community resources and to generate political commitments for health programmes.     

An epidemic of poliomyelitis in southern Kerala

An epidemic of poliomyelitis was recognized in May 1987 when there was a sharp increase in the number of children with acute paralytic poliomyelitis admitted to the SAT Hospital in Trivandrum in Kerala State. From May through September, 392 cases were admitted; the total admitted cases in 1987 were 458 in contrast to 119 in 1986. Evidence for type 1 poliovirus infection was found in 33 (85%) of the 39 children in whom virological investigations were done during the epidemic. In addition, evidence for poliovirus type 3 infection was found in four children. Data on the immunization status was available on 231 affected children in the epidemic; 175 (76%) had not received oral polio vaccine (OPV); 55 (24%) had received one or two doses and only one child had received three doses. Thus, lack of immunization was a major risk factor for disease. The estimated vaccine coverage with three doses of OPV in Kerala, based on the quantity of vaccine distributed during the years 1985, 1986 and 1987 were 94%, 100% and 91%, respectively. This outbreak occurred in spite of high vaccine coverage, and it illustrates the need for even higher coverage rates; the usefulness of hospitals as sentinel surveillance centres; the need for decentralized vaccine coverage data in order to prevent build-up of unimmunized susceptible children in any region; and the urgent need of a mechanism to respond to an epidemic quickly, with immunization, in order to curtail it.     

Paralytic poliomyelitis associated with Sabin monovalent and bivalent oral polio vaccines in Hungary

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

Cost analysis of post-polio certification immunization policies

OBJECTIVE: An analysis was conducted to estimate the costs of different potential post-polio certification immunization policies currently under consideration, with the objective of providing this information to policy-makers. METHODS: We analyzed three global policy options: continued use of oral poliovirus vaccine (OPV); OPV cessation with optional inactivated poliovirus vaccine (IPV); and OPV cessation with universal IPV. Assumptions were made on future immunization policy decisions taken by low-, middle-, and high-income countries. We estimated the financial costs of each immunization policy, the number of vaccine-associated paralytic poliomyelitis (VAPP) cases, and the global costs of maintaining an outbreak response capacity. The financial costs of each immunization policy were based on estimates of the cost of polio vaccine, its administration, and coverage projections. The costs of maintaining outbreak response capacity include those associated with developing and maintaining a vaccine stockpile in addition to laboratory and epidemiological surveillance. We used the period 2005-20 as the time frame for the analysis. FINDINGS: OPV cessation with optional IPV, at an estimated cost of US$ 20,412 million, was the least costly option. The global cost of outbreak response capacity was estimated to be US$ 1320 million during 2005-20. The policy option continued use of OPV resulted in the highest number of VAPP cases. OPV cessation with universal IPV had the highest financial costs, but it also had the least number of VAPP cases. Sensitivity analyses showed that global costs were sensitive to assumptions on the cost of the vaccine. Analysis also showed that if the price per dose of IPV was reduced to US$ 0.50 for low-income countries, the cost of OPV cessation with universal IPV would be the same as the costs of continued use of OPV. CONCLUSION: Projections on the vaccine price per dose and future coverage rates were major drivers of the global costs of post-certification polio immunization. The break-even price of switching to IPV compared with continuing with OPV immunizations is US$ 0.50 per dose of IPV. However, this doses not account for the cost of vaccine-derived poliovirus cases resulting from the continued use of OPV. In addition to financial costs, risk assessments related to the re-emergence of polio will be major determinants of policy decisions.     

Isolation of epidemic poliovirus from sewage during the 1992-3 type 3 outbreak in The Netherlands.

To examine the extent of wild poliovirus circulation during the 1992-3 epidemic in the Netherlands caused by poliovirus type 3, 269 samples from sewage pipelines at 120 locations were examined for the presence of poliovirus. The epidemic virus strain was found in 23 samples, all from locations inside the risk area which contained communities that refuse vaccination for religious reasons. By sewage investigation, the wildtype virus was shown to be present in the early phase of the epidemic at two locations, one week before patients were reported from that area. The wild type 3 poliovirus was also detected retrospectively in a river water sample collected for other reasons three weeks before notification of the first poliomyelitis case, at a site a few kilometres upstream the home village of this patient. Oral poliovirus vaccine (OPV) virus was found at 28 locations inside or at the border of the risk area. Trivalent OPV was offered to unvaccinated or incompletely-vaccinated persons living in this region as part of the measures to control the epidemic.     

济南市污水中监测到Ⅱ型疫苗高变异脊髓灰质炎病毒/疫苗衍生脊髓灰质炎病毒后的流行病学调查和处置

目的对济南市环境污水中监测到Ⅱ型（Type2）疫苗高变异脊髓灰质炎（脊灰）病毒（Vaccine Hypervariable P0liovirus,VHPVⅡ）/疫苗衍生脊灰病毒（Vaccine-derived Poliovirus,VDPVII）后,进行流行病学调查和处置,为维持无脊灰提供参考。方法对济南市口服脊灰减毒活疫苗（Oral Poliomyelitis Attenuate dLive Vaccine,OPV）常规免疫和补充免疫活动进行评估,开展0～47月龄儿童OPV接种率调查,对急性弛缓性麻痹（Acute Flaccid Paralysis,AFP）病例监测情况进行评价,继续采集污水标本开展脊灰病毒监测。结果济南市适龄儿童OPV各剂次接种率均〉99％,2010～2012年全市〈15岁儿童非脊灰AFP病例报告发病率均〉1/10万,合格粪便标本采集率均〉90％,AFP病例监测系统灵敏,能够及时发现病例,后续采集的污水中未检测到VHPV/VDPV。结论VHPV/VDPV在当地引起传播的风险较小,但污水采集点辐射范围内流动人口较多,应进一步加强AFP病例监测和OPV接种,防止VHPV/VDPV在人群中循环。     

Poliomyelitis outbreaks in Angola genetically linked to India: risk factors and implications for prevention of outbreaks due to wild poliovirus importations

We conducted an investigation of two outbreaks of poliomyelitis in Angola during 2007-2008 due to wild poliovirus (WPV) genetically linked to India. A case-control study including 27 case-patients and 76 age- and neighborhood-matched control-subjects was conducted to assess risk factors associated with paralytic poliomyelitis, and epidemiologic links to India were explored through in-depth case-patient interviews. In multivariable analysis, case-patients were more likely than control-subjects to be undervaccinated with fewer than four routine doses of oral poliovirus vaccine (adjusted matched odds ratio [aMOR], 4.1; 95% confidence interval [CI], 1.2-13.6) and have an adult household member who traveled outside the province of residence in the 2 months preceding onset of paralysis (aMOR, 3.2; 95% CI, 1.2-8.6). No epidemiologic link with India was identified. These findings underscore the importance of routine immunization to prevent outbreaks following WPV importations and suggest a possible role of adults in sustaining WPV transmission.