Missed opportunities: Reducing zero dose children amongthe urban poor after COVID, Mumbai India, 2022.

Reaching urban poor populations poses challenges for equitable immunization coverage. Furthermore, COVID disrupted routine immunization services. In Mumbai, India, first dose diphtheria tetanus pertussis containing vaccine (DTPCV1)coverage dropped from 88% (2019) to 76% (2021). We identified and characterized 125 zero-dose (those withoutDTPCV1)migrant children in urban Mumbai in October 2022. Almost half were born elsewhere than Mumbai; 53% resided at their present location for less than a year. More than half were 12-59 months of age, well-beyond the age for first routine childhood immunizations.Three of four zero dose children had received birth dose vaccination in the hospital; but failed to receive DTPCV1. Vaccine hesitancy, awareness gaps and operational issues were common reasons for non-vaccination. Despite frequent visits to health facilities for illness,only a third of facility staff asked or advised parents about vaccination.Missed opportunities were much more common in private than government facilities.For the vast majority (88%), residential sites were included in local routine immunization micro-plans and distances to immunization sites were short (less than 1 km for 94 % of families).However, planned session frequency was inadequate half of the time. Expanded efforts to reach migrant urban poor children are needed to ensure vaccine equity.

Overlooked Symptoms in Autoimmune Hepatitis Negatively Impact Many Facets of Life.

BACKGROUND: Significant reduction in quality of life among patients with autoimmune hepatitis (AIH) patients has been observed in several studies. While acute symptoms associated with AIH have been well described, little is known about the overall impact of living with AIH on patients' quality of life. The aim of this qualitative descriptive study was to describe the impact of AIH and associated symptoms on quality of life from the perspectives of patients living with AIH. METHODS: Patients from Autoimmune Hepatitis Association support groups were recruited to participate in one of five online focus groups conducted between August and September 2020. After enrollment, patients were asked to complete a brief demographic and disease history questionnaire. A single moderator conducted interviews with each group guided by seven questions focused on the impact of AIH on the participants' quality of life. Each session was recorded, transcribed, and verified. Content analysis was used to summarize the participants' responses. RESULTS: The participants' discussed three overarching topics: (a) symptoms of AIH and medication side effects, (b) the impact the disease and symptoms/side effects on five domains of quality of life (work life, relationships with friends and family, social life, leisure activities, and diet and exercise) and (c) interactions with healthcare providers and recommendations for future research. CONCLUSIONS: Living with AIH can have profound effects on patients' quality of life in several domains. Healthcare providers and the AIH research community should focus on developing further strategies that can improve the quality of life in persons suffering from AIH.

Assessment of vaccine wastage rates, missed opportunities, and related knowledge, attitudes and practices during introduction of a second dose of measles-containing vaccine into Cambodia's national immunization program.

INTRODUCTION: Missed opportunities for vaccination (MOV) can result in inadequate protection against disease. Although healthcare provider reluctance to open multi-dose, lyophilized vaccine vials (particularly the measles-containing vaccine [MCV]) for every eligible child due to concerns about wasting vaccine is a known reason for MOV, little is known about providers' related attitudes and practices. METHODS: In 100 randomly selected health facilities and 24 districts of Cambodia, we surveyed healthcare providers and their district supervisors regarding routine vaccine administration and wastage knowledge and practices, and child caregivers (five per facility) regarding MOV. Vaccine stock management data covering six months were reviewed to calculate facility and district level wastage rates and vaccine usage patterns for six vaccines, including a recently introduced second dose of MCV (MCV2). RESULTS: Response rates were 100/100 (100%) among facility staff, 48/48 (100%) among district staff, and 436/500 (87%) among caregivers. Mean facility-level wastage rates varied from 4% for single-dose diphtheria-tetanus-pertussis-hepatitis B-Haemophilus influenzae type b vaccine to 60% for 10-dose MCV; district-level wastage rates for all vaccines were 0%. Some vaccines had lower wastage rates in large facilities compared to small facilities. The mean MCV wastage rate was the same before and immediately after MCV2 introduction. Providers reported waiting for a mean of two children prior to opening an MCV vial, and 71% of providers reported offering MCV vaccination less frequently during scheduled vaccination sessions than other vaccines. Less than 5% of caregivers reported that their child had been turned away for vaccination, most frequently (65%) for MCV. DISCUSSION: Although the MCV wastage rate in our study was in line with national targets, providers reported waiting for more than one child before opening an MCV vial, contrary to vaccine management guidelines. Future research should explore the causal links between provider practices related to vaccine wastage and their impact on vaccination coverage.

Knowledge, attitudes, and practices of private sector immunization service providers in Gujarat, India.

BACKGROUND: India is responsible for 30% of the annual global cohort of unvaccinated children worldwide. Private practitioners provide an estimated 21% of vaccinations in urban centers of India, and are important partners in achieving high vaccination coverage. METHODS: We used an in-person questionnaire and on-site observation to assess knowledge, attitudes, and practices of private immunization service providers regarding delivery of immunization services in the urban settings of Surat and Baroda, in Gujarat, India. We constructed a comprehensive sampling frame of all private physician providers of immunization services in Surat and Baroda cities, by consulting vaccine distributors, local branches of physician associations, and published lists of private medical practitioners. All providers were contacted and asked to participate in the study if they provided immunization services. Data were collected using an in-person structured questionnaire and directly observing practices; one provider in each practice setting was interviewed. RESULTS: The response rate was 82% (121/147) in Surat, and 91% (137/151) in Baroda. Of 258 participants 195 (76%) were pediatricians, and 63 (24%) were general practitioners. Practices that were potential missed opportunities for vaccination (MOV) included not strictly following vaccination schedules if there were concerns about ability to pay (45% of practitioners), and not administering more than two injections in the same visit (60%). Only 22% of respondents used a vaccination register to record vaccine doses, and 31% reported vaccine doses administered to the government. Of 237 randomly selected vaccine vials, 18% had expired vaccine vial monitors. CONCLUSIONS: Quality of immunization services in Gujarat can be strengthened by providing training and support to private immunization service providers to reduce MOVs and improve quality and safety; other more context specific strategies that should be evaluated may involve giving feedback to providers on quality of services delivered and working through professional societies to adopt standards of practice.

Missed opportunities and barriers for vaccination: a descriptive analysis of private and public health facilities in four African countries.

INTRODUCTION: Missed opportunities and barriers to vaccination limit progress toward achieving high immunization coverage and other global immunization goals. Little is known about vaccination practices contributing to missed opportunities and barriers among private healthcare providers in Africa. METHODS: Service Provision Assessments (SPA) of representative samples of health facilities in four African countries (Kenya, Tanzania, Senegal, Malawi) in 2010-2015 were used to describe missed opportunities and barriers for vaccination in public, private for-profit, private not-for-profit and faith-based facilities. Data included vaccination practices, observations during sick child and antenatal visits, and exit interviews following sick child visits. RESULTS: Data from 3,219 health facilities, 11,613 sick child visits and 8,698 antenatal visits were included. A smaller proportion of for-profit facilities offered child vaccination services (country range, 25-37%) than did public facilities (range, 90-96%). The proportion of facilities offering pentavalent vaccine (diphtheria, pertussis, tetanus, hepatitis B and Haemophilus influenza type b antigens) daily ranged 0-77% across countries and facility types. Less than 33% of for-profit facilities in any country offered measles vaccination daily. A minority of public or private providers assessed the child's vaccination status during a sick child visit (range by country and facility type, 14-44%), or offered tetanus toxoid during antenatal visits (range, 19-51%). Very few providers discussed the importance of newborn vaccination. CONCLUSION: Substantial missed opportunities for, and barriers to, vaccination were identified across this representative sample of health facilities in four African countries. Strategies are needed to ensure that private and public providers implement practices to minimize barriers and missed opportunities for vaccination.

Missed opportunities and barriers for vaccination: a descriptive analysis of private and public health facilities in four African countries

Introduction: missed opportunities and barriers to vaccination limit progress toward achieving high immunization coverage and other global immunization goals. Little is known about vaccination practices contributing to missed opportunities and barriers among private healthcare providers in Africa.Methods: Service Provision Assessments (SPA) of representative samples of health facilities in four African countries (Kenya, Tanzania, Senegal, Malawi) in 2010-2015 were used to describe missed opportunities and barriers for vaccination in public, private for-profit, private not-for-profit and faith-based facilities. Data included vaccination practices, observations during sick child and antenatal visits, and exit interviews following sick child visits.Results: data from 3,219 health facilities, 11,613 sick child visits and 8,698 antenatal visits were included. A smaller proportion of for-profit facilities offered child vaccination services (country range, 25-37%) than did public facilities (range, 90-96%). The proportion of facilities offering pentavalent vaccine (diphtheria, pertussis, tetanus, hepatitis B and Haemophilus influenza type b antigens) daily ranged 0-77% across countries and facility types. Less than 33% of for-profit facilities in any country offered measles vaccination daily. A minority of public or private providers assessed the child's vaccination status during a sick child visit (range by country and facility type, 14-44%), or offered tetanus toxoid during antenatal visits (range, 19-51%). Very few providers discussed the importance of newborn vaccination. Conclusion: substantial missed opportunities for, and barriers to, vaccination were identified across this representative sample of health facilities in four African countries. Strategies are needed to ensure that private and public providers implement practices to minimize barriers and missed opportunities for vaccination

Diphtheria outbreak in Lao People's Democratic Republic, 2012-2013.

BACKGROUND: Diphtheria is a vaccine-preventable disease. When vaccination coverage and population immunity are low, outbreaks can occur. We investigated a diphtheria outbreak in Lao People's Democratic Republic that occurred during 2012-2013 and highlighted challenges in immunization services delivery to children in the country. METHODS: We reviewed diphtheria surveillance data from April 1, 2012-May 31, 2013. A diphtheria case was defined as a respiratory illness consisting of pharyngitis, tonsillitis, or laryngitis, and an adherent tonsillar or nasopharyngeal pseudomembrane. To identify potential risk factors for diphtheria, we conducted a retrospective case-control study with two aged-matched neighborhood controls per case-patient in Houaphan Province, using bivariate analysis to calculate matched odds ratio (mOR) with 95% confidence intervals (CI). Reasons for non-vaccination among unvaccinated persons were assessed. RESULTS: Sixty-two clinical cases of diphtheria and 12 diphtheria-related deaths were reported in seven of 17 provinces. Among case-patients, 43 (69%) were <15years old, five (8%) reported receiving three DTP doses (DTP3), 21 (34%) had received no DTP doses, and 35 (56%) had unknown vaccination status. For the case-control study, 42 of 52 diphtheria case-patients from Houaphan province and 79 matched-controls were enrolled. Five (12%) case-patients and 20 (25%) controls had received DTP3 (mOR=0.4, CI=0.1-1.7). No diphtheria toxoid-containing vaccine was received by 20 (48%) case-patients and 38 (46%) controls. Among case-patients and controls with no DTP dose, 43% of case-patients and 40% of controls lacked access to routine immunization services. CONCLUSION: Suboptimal DTP3 coverage likely caused the outbreak. To prevent continued outbreaks, access to routine immunization services should be strengthened, outreach visits need to be increased, and missed opportunities need to be minimized. In the short term, to rapidly increase population immunity, three rounds of DTP immunization campaign should be completed, targeting children aged 0-14years in affected provinces.

Outbreak of type 1 wild poliovirus infection in adults, Namibia, 2006.

A paralytic poliomyelitis outbreak occurred in Namibia in 2006, almost exclusively among adults. Nineteen cases were virologically confirmed as due to wild poliovirus type 1 (WPV1), and 26 were classified as polio compatible. Eleven deaths occurred among confirmed and compatible cases (24%). Of the confirmed cases, 97% were aged 15-45 years, 89% were male, and 71% lived in settlement areas in Windhoek. The virus was genetically related to a virus detected in 2005 in Angola, which had been imported earlier from India. The outbreak is likely due to immunity gaps among adults who were inadequately vaccinated during childhood. This outbreak underscores the ongoing risks posed by poliovirus importations, the importance of maintaining strong acute flaccid paralysis surveillance even in adults, and the need to maintain high population immunity to avoid polio outbreaks in the preeradication period and outbreaks due to vaccine-derived polioviruses in the posteradication era.

Integrating pneumonia prevention and treatment interventions with immunization services in resource-poor countries.

Pneumonia is a leading cause of morbidity and mortality worldwide. Effective vaccine and non-vaccine interventions to prevent and control pneumonia are urgently needed to reduce the global burden of the disease. This paper explores practical strategies and policies for integrating interventions to prevent and treat pneumonia with routine immunization services, and it investigates the challenges involved in such integration. The primary pneumonia prevention and treatment strategies that are implemented during routine childhood immunization visits are vaccination of children against the disease, caretaker education and referral of children to medical services when necessary.

Community and health worker perceptions and preferences regarding integration of other health services with routine vaccinations: four case studies.

BACKGROUND: Integration of routine vaccination and other maternal and child health services is becoming more common and the services being integrated more diverse. Yet knowledge gaps remain regarding community members and health workers acceptance, priorities, and concerns related to integration. METHODS: Qualitative health worker interviews and community focus groups were conducted in 4 African countries (Kenya, Mali, Ethiopia, and Cameroon). RESULTS: Integration was generally well accepted by both community members and health workers. Most integrated services were perceived positively by the communities, although perceptions around socially sensitive services (eg, family planning and human immunodeficiency virus) differed by country. Integration benefits reported by both community members and health workers across countries included opportunity to receive multiple services at one visit, time and transportation cost savings, increased service utilization, maximized health worker efficiency, and reduced reporting requirements. Concerns related to integration included being labor intensive, inadequate staff to implement, inadequately trained staff, in addition to a number of more broad health system issues (eg, stockouts, wait times). CONCLUSIONS: Communities generally supported integration, and integrated services may have the potential to increase service utilization and possibly even reduce the stigma of certain services. Some concerns expressed related to health system issues rather than integration, per se, and should be addressed as part of a wider approach to improve health services. Improved planning and patient flow and increasing the number and training of health staff may help to mitigate logistical challenges of integrating services.

Impact of integration of hygiene kit distribution with routine immunizations on infant vaccine coverage and water treatment and handwashing practices of Kenyan mothers.

Integration of immunizations with hygiene interventions may improve use of both interventions. We interviewed 1361 intervention and 1139 comparison caregivers about hygiene practices and vaccination history, distributed water treatment and hygiene kits to caregivers during infant vaccination sessions in intervention clinics for 12 months, and conducted a followup survey of 2361 intervention and 1033 comparison caregivers. We observed significant increases in reported household water treatment (30% vs 44%, P < .0001) and correct handwashing technique (25% vs 51%, P < .0001) in intervention households and no changes in comparison households. Immunization coverage improved in both intervention and comparison infants (57% vs 66%, P = .04; 37% vs 53%, P < .0001, respectively). Hygiene kit distribution during routine immunizations positively impacted household water treatment and hygiene without a negative impact on vaccination coverage. Further study is needed to assess hygiene incentives, implement alternative water quality indicators, and evaluate the impact of this intervention in other settings.

Integration of routine vaccination and hygiene interventions: a comparison of 2 strategies in Kenya.

BACKGROUND: Hygiene interventions reduce child mortality from diarrhea. Vaccination visits provide a platform for delivery of other health services but may overburden nurses. We compared 2 strategies to integrate hygiene interventions with vaccinations in Kenya's Homa Bay district, 1 using community workers to support nurses and 1 using nurses. METHODS: Homa Bay was divided into 2 geographical areas, each with 9 clinics. Each area was randomly assigned to either the nurse or community-assisted strategy. At infant vaccination visits hygiene kits were distributed by the nurse or community member. Surveys pre- and post-intervention, measured hygiene indicators and vaccination coverage. Interviews and focus groups assessed acceptability. RESULTS: Between April 2009 and March 2010, 39 158 hygiene kits were distributed. Both nurse and community-assisted strategies were well-accepted. Hygiene indicators improved similarly in nurse and community sites. However, residual chlorine in water changed in neither group. Vaccination coverage increased in urban areas. In rural areas coverage either remained unchanged or increased with 1 exception (13% third dose poliovirus vaccine decrease). CONCLUSIONS: Distribution of hygiene products and education during vaccination visits was found to be feasible using both delivery strategies. Additional studies should consider assessing the use of community members to support integrated service delivery.

Contribution of Immunization Weeks toward improving coverage, access to services, and completion of recommended childhood vaccinations in Assam, India.

Recommended childhood vaccines have typically been provided through routine immunization programs. Recently, implementation of strategies that use campaign-like features for providing all the recommended childhood immunizations have been utilized to increase vaccination coverage. Between January 2006 and January 2008, Assam, India, conducted Immunization Weeks (IWs), a periodic campaign-like approach for providing the recommended childhood vaccines generally administered through the routine Universal Immunization Program (UIP). Using data from a household vaccination coverage survey conducted in 5 districts of Assam in late-2007/early-2008 among children 12-28 months of age, a secondary analysis was conducted for a subset of children with vaccination cards to assess the impacts of implementing the IW-strategy. Sixty-five percent of the 3310 surveyed children received at least one vaccine dose through an IW. Without IWs, coverage would likely have been lower for all vaccines (e.g., 75% measles vaccine coverage including IWs doses and an estimated 61% without IWs). The proportion of children receiving at least one IW dose was significantly different depending on the child's residence; 72% in hard-to-reach char areas, 66% in rural areas and 53% in urban areas (p=0.01). Overall, 2085 (63%) of children were fully vaccinated; of these 60% received a combination of IW and UIP doses, 35% received doses only through the UIP, and 5% received doses only through IWs. A delay in administration later than the recommended ages was found for both UIP doses and for IW doses (e.g., for measles vaccine, UIP doses were 6.9 weeks delayed and IW doses 13.6 weeks delayed). Among this sample of vaccinated children, IWs appeared to increase vaccination coverage and improve access to services in hard-to-reach areas. However, the UIP appeared to be a better system for ensuring that children received all doses in the recommended vaccination series.

Reasons related to non-vaccination and under-vaccination of children in low and middle income countries: findings from a systematic review of the published literature, 1999-2009.

OBJECTIVE: Despite increases in routine vaccination coverage during the past three decades, the percent of children completing the recommended vaccination schedule remains below expected targets in many low and middle income countries. In 2008, the World Health Organization Strategic Advisory Group of Experts on Immunization requested more information on the reasons that children were under-vaccinated (receiving at least one but not all recommended vaccinations) or not vaccinated in order to develop effective strategies and interventions to reach these children. METHODS: A systematic review of the peer-reviewed literature published from 1999 to 2009 was conducted to aggregate information on reasons and factors related to the under-vaccination and non-vaccination of children. A standardized form was used to abstract information from relevant articles identified from eight different medical, behavioural and social science literature databases. FINDINGS: Among 202 relevant articles, we abstracted 838 reasons associated with under-vaccination; 379 (45%) were related to immunization systems, 220 (26%) to family characteristics, 181 (22%) to parental attitudes and knowledge, and 58 (7%) to limitations in immunization-related communication and information. Of the 19 reasons abstracted from 11 identified articles describing the non-vaccinated child, 6 (32%) were related to immunization systems, 8 (42%) to parental attitudes and knowledge, 4 (21%) to family characteristics, and 1 (5%) to communication and information. CONCLUSIONS: Multiple reasons for under-vaccination and non-vaccination were identified, indicating that a multi-faceted approach is needed to reach under-vaccinated and unvaccinated children. Immunization system issues can be addressed through improving outreach services, vaccine supply, and health worker training; however, under-vaccination and non-vaccination linked to parental attitudes and knowledge are more difficult to address and likely require local interventions.

Researching routine immunization-do we know what we don't know?

BACKGROUND: The Expanded Programme on Immunization (EPI), launched in 1974, has developed and implemented a range of strategies and practices over the last three decades to ensure that children and adults receive the vaccines they need to help protect them against vaccine-preventable diseases. Many of these strategies have been implemented, resulting in immunization coverage exceeding 80% among children one year of age in many countries. Yet millions of infants remain under-immunized or unimmunized, particularly in poorer countries. In November 2009, a panel of external experts met at the United States Centers for Disease Control and Prevention (CDC) to review and identify areas of research required to strengthen routine service delivery in developing countries. METHODS: Research opportunities were identified utilizing presentations emphasizing existing research, gaps in knowledge and key questions. Panel members prioritized the topics, as did other meeting participants. FINDINGS: Several hundred research topics covering a wide range were identified by the panel members and participants. However there were relatively few topics for which there was a consensus that immediate investment in research is warranted. The panel identified 28 topics as priorities. 18 topics were identified as priorities by at least 50% of non-panel participants; of these, five were also identified as priorities by the panel. Research needs included identifying the best ways to increase coverage with existing vaccines and introduce new vaccines, integrate other services with immunizations, and finance immunization programmes. INTERPRETATION: There is an enormous range of research that could be undertaken to support routine immunization. However, implementation of strategic plans, rather than additional research will have the greatest impact on raising immunization coverage and preventing disease, disability, and death from vaccine-preventable diseases. The panel emphasized the importance of tying operational research to programmatic needs, with a focus on efforts to scale up proven best practices in each country, facilitating the full implementation of immunization strategies.

Uncertainty and sensitivity analyses of a decision analytic model for posteradication polio risk management.

Decision analytic modeling of polio risk management policies after eradication may help inform decisionmakers about the quantitative tradeoffs implied by various options. Given the significant dynamic complexity and uncertainty involving posteradication decisions, this article aims to clarify the structure of a decision analytic model developed to help characterize the risks, costs, and benefits of various options for polio risk management after eradication of wild polioviruses and analyze the implications of different sources of uncertainty. We provide an influence diagram of the model with a description of each component, explore the impact of different assumptions about model inputs, and present probability distributions of model outputs. The results show that choices made about surveillance, response, and containment for different income groups and immunization policies play a major role in the expected final costs and polio cases. While the overall policy implications of the model remain robust to the variations of assumptions and input uncertainty we considered, the analyses suggest the need for policymakers to carefully consider tradeoffs and for further studies to address the most important knowledge gaps.

The risks, costs, and benefits of possible future global policies for managing polioviruses.

OBJECTIVES: We assessed the costs, risks, and benefits of possible future major policy decisions on vaccination, surveillance, response plans, and containment following global eradication of wild polioviruses. METHODS: We developed a decision analytic model to estimate the incremental cost-effectiveness ratios and net benefits of risk management options for polio for the 20-year period and stratified the world according to income level to capture important variability between nations. RESULTS: For low-, lower-middle-, and upper-middle-income groups currently using oral poliovirus vaccine (OPV), we found that after successful eradication of wild polioviruses, OPV cessation would save both costs and lives when compared with continued use of OPV without supplemental immunization activities. We found cost-effectiveness ratios for switching from OPV to inactivated poliovirus vaccine to be higher (i.e., less desirable) than other health investment opportunities, depending on the actual inactivated poliovirus vaccine costs and assumptions about whether supplemental immunization activities with OPV would continue. CONCLUSIONS: Eradication promises billions of dollars of net benefits, although global health policy leaders face difficult choices about future policies. Until successful eradication and coordination of posteradication policies, health authorities should continue routine polio vaccination and supplemental immunization activities.

A large vaccine-derived poliovirus outbreak on Madura Island--Indonesia, 2005.

Between June and October 2005, 45 laboratory-confirmed type 1 vaccine-derived poliovirus (VDPV) cases were identified on Madura Island in Indonesia. Genetic sequencing data on VDPV isolates were consistent with replication and circulation for up to approximately 2 years. Concurrent circulation with type 1 wild poliovirus (WPV) enabled comparisons of VDPV and WPV cases and found that clinical and epidemiological features of both were similar. Attack rates for VDPV were as high as those for WPV. Of 41 VDPV case patients with known vaccination status, 25 (61%) had received zero oral polio vaccine (OPV) doses. Low population immunity due to low routine OPV coverage in rural areas and the absence of WPV circulation for more than a decade were major predisposing factors for the emergence of VDPV. Suboptimal surveillance and a limited initial immunization response may have contributed to widespread circulation. Sensitive surveillance and prompt high-quality immunization responses are recommended to prevent the spread of VDPVs.

Survey of poliovirus antibodies during the final stage of polio eradication in Egypt.

BACKGROUND: Egypt provides ideal conditions for poliovirus (PV) transmission (high population density, high contact rates and low sanitation and hygiene in some areas). Despite excellent program performance, wild poliovirus type 1 (PV1) continue to circulate in 2004. To investigate potential causes for the persistence, we conducted a serological study. METHODS: Seroprevalence surveys were conducted in "polio-endemic" regions (Greater Cairo and Upper Egypt) and in one control region (Lower Egypt) in December 2004. Sera collected from infants aged 6-11 months were tested for antibodies to poliovirus by neutralization assay. RESULTS: A total of 973 subjects were tested. Seroprevalence to PV type 1 (PV1), PV type 2 (PV2) and PV type 3 (PV3) was 99, 99 and 91%, respectively. Significant variation in PV3 seroprevalence was found (range: 76-100%). Region, density, maternal education, socioeconomic status (SES), stunting and diarrhea were significant risk factors for lower seroprevalence in the univariate analysis. CONCLUSIONS: Our study suggested that uniformly high immunity levels (>96%) were required to interrupt PV1 transmission in the last remaining reservoirs (last PV1 was isolated in mid-January 2005 in Egypt). It further suggests substantial regional differences in OPV immunogenicity, with rural areas and low SES achieving the lowest seroprevalence to PV3.