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WHAT'S NEW THIS TUESDAY: THREE ON POLIO: NIGERIA, PAKISTAN, AFGHANISTAN

Sunday, 18th of November 2012 Print

 

  • THREE ON POLIO: NIGERIA, PAKISTAN, AFGHANISTAN

 

  • POLIO IN NIGERIA

‘Continuing WPV transmission in Nigeria poses an ongoing risk for WPV reintroduction into polio-free countries and is a major obstacle to the success of global eradication. Recent initiatives by government and partners have yet to demonstrate their impact epidemiologically, but indicate promise. If WPV case counts and extent of circulation are not reduced substantially by mid-2013, additional innovative strategies to interrupt WPV transmission might need to be considered.’

Progress Toward Poliomyelitis Eradication — Nigeria, January 2011–September 2012

Morbidity and Mortality Weekly Report

Best viewed at http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6144a4.htm?s_cid=mm6144a4_w

Also available, in French and English, at http://www.who.int/wer/2012/wer8745.pdf

November 9, 2012 / 61(44);899-904

In 1988, the World Health Assembly launched the Global Polio Eradication Initiative (GPEI) and, in 2012, declared the completion of polio eradication a programmatic emergency for global public health (1). To date, wild poliovirus (WPV) cases reported worldwide in 2012 are at historically low levels. Nigeria is one of only three countries with uninterrupted WPV transmission (in addition to Pakistan and Afghanistan) and has been the origin of WPV imported into 25 previously polio-free countries since 2003 (2–4). This report updates previous reports (2–3,5) and describes polio eradication activities and progress in Nigeria during January 2011–September 2012, as of October 30, 2012. The number of reported WPV cases increased from 21 in 2010 to 62 in 2011. During January–September 2012, a total of 99 WPV cases were reported, more than doubling from the 42 cases reported during the same period in 2011. During 2011, a total of 32 circulating vaccine-derived polio virus type 2 (cVDPV2) cases were confirmed; six cVDPV2 cases were confirmed during January–September 2012, compared with 18 cVDPV2 cases during the same period in 2011. Nigeria's 2012 Polio Eradication Emergency Plan (6) includes senior government leadership oversight, new program management and strategic initiatives, an accountability framework, and a surge in human resources to address chronically missed children during supplemental immunization activities (SIAs).* In 2012, indicators of immunization campaign quality show modest improvements; available data indicate gaps in surveillance. Continuing WPV transmission in Nigeria poses an ongoing risk for WPV reintroduction and outbreaks in polio-free countries and is a major obstacle to achieving global eradication (7).

Vaccination Activities

Infants and children are vaccinated against polio as part of a routine vaccination program and through SIAs. The estimated national routine vaccination coverage of infants with 3 doses of trivalent oral poliovirus vaccine (OPV) in Nigeria was 73% in 2011, compared with 54% in 2007 (8). Surveys indicate substantially lower coverage than the national average in the northern states, with wide variation within the majority of northern states.†

During January 2011–September 2012, one national and 10 subnational SIAs were conducted, primarily in high-risk northern states, targeting children aged <5 years using bivalent OPV type 1 and 3, as well as three national and four subnational SIAs using trivalent OPV. After the four campaigns conducted during January–September 2012, lot quality-assurance sampling§ surveys were used to assess the quality of SIAs in reaching all children. The proportion of sampled local government areas (LGAs) (equivalent to districts), in the 12 high-risk northern states that failed to meet the <20% missed children threshold was 82% (72 of 88) after the February 2012 SIA; the proportion decreased over subsequent SIAs: 74% (68 of 92) after the March SIA, 65% (70 of 108) after the May SIA, and 63% (91 of 145) after the July SIA.¶

A surrogate measure of OPV coverage through routine vaccination and SIAs is based on parental recall and vaccination cards of children aged 6–35 months with acute flaccid paralysis (AFP) not attributed to poliovirus (nonpolio AFP [NPAFP]). During all of 2011 and January–September 2012, 3% of children aged 6–35 months in high-risk northern states with NPAFP had never received a dose of OPV ("zero-dose children"), compared with 7% in 2010; the proportion of children in high-risk northern states with NPAFP cases who received ≥4 doses of OPV was 75% in 2011 and 76% during January–September 2012, compared with 60% in 2010 (Table).

Poliovirus Surveillance

AFP surveillance. Polio surveillance depends on detection of AFP cases with confirmation of poliomyelitis by viral isolation. Quality surveillance is measured through performance indicators with defined targets: NPAFP detection rates of ≥2 cases per 100,000 children aged <15 years and adequate stool specimen collection** in ≥80% of AFP cases. In 2011, the annual national NPAFP rate (per 100,000 population aged <15 years) was 7.9, and the proportion of AFP cases with adequate specimen collection was 93%. To date, the annualized national NPAFP rate in 2012 is 9.2, and the proportion of AFP cases with adequate specimen collection is 94%. Both indicators were met in all states during 2011 and all but one state during January–September 2012 (Table). The proportions of LGAs in high-risk northern states that met each indicator in 2011 and January–September 2012 were 82% and 80%, respectively.

Environmental surveillance. To supplement AFP surveillance, collection of sewage samples every 4–5 weeks for poliovirus testing began in July 2011 at three sites in Kano state. During July–December 2011, cVDPV2 was isolated from 12 (67%) of 18 samples collected from Kano; during January–September 2012, of 25 collected, WPV type 3 (WPV3) was isolated from one specimen (4%), and cVDPV2 was isolated from three specimens (12%). Environmental surveillance every 2 weeks at four sites in Sokoto began in March 2012, and WPV1 and cVDPV2 were detected in 15 specimens (30%) and 22 specimens (44%), respectively, of 50 collected. During January–September 2012, AFP surveillance confirmed 18 WPV1, three WPV3, and three cVDPV2 cases in Kano; in Sokoto, eight WPV1 cases and three cVDPV2 cases were confirmed, indicating variability in environmental surveillance sensitivity possibly attributable to site selection.

WPV and cVDPV Case Incidence

During 2011, a total of 62 WPV (47 WPV1 and 15 WPV3) cases were reported in Nigeria, compared with 21 (eight WPV1 and 13 WPV3) cases in 2010, an increase of 195%; 99 WPV (82 WPV1 and 17 WPV3) cases were reported during January–September 2012, compared with 42 (33 WPV1 and nine WPV3) cases during the same period in 2011 (Figures 1 and 2), an increase of 136%. Cases occurred in 42 LGAs in eight states in 2011 and 55 LGAs in 11 states in 2012; all cases occurred in high-risk northern states, with the exception of one WPV3 case reported in Taraba in July 2012. Of 161 cases with onset during January 2011–September 2012, 148 (92%) occurred in children aged <5 years, and 13 (8%) occurred among children aged 5–14 years; 40 (25%) were "zero-dose" children, and 58 (36%) were children reported to have received ≥4 doses of OPV.

During 2011, a total of 32 cVDPV2 transmission cases were confirmed, a 19% increase from 27 cVDPV2 cases in 2010; six cVDPV2 cases were reported during January–September 2012, a 67% decrease from 18 cases during the same period in 2011 (Figures 1 and 2). Cases occurred in 27 LGAs in eight states in 2011 and three LGAs in two states (Kano and Sokoto) in 2012. Of 38 cases with onset during January 2011–September 2012, a total of 37 (97%) occurred in children aged <5 years, and one (3%) occurred among children aged 5–14 years; seven (18%) were "zero-dose" children, and 17 (45%) were children reported to have received ≥4 doses of OPV.

WPV and cVDPV Genomic Sequence Analysis

Analysis of the nucleotide sequence of the VP1 region of all WPV and cVDPV2 isolates is used to investigate transmission links, track international spread, and assess both viral diversity as a measure of circulation intensity and surveillance sensitivity (9).†† After a substantial decline in the genetic diversity (reflected by the number of genetic clusters) of WPV1 strains from 21 clusters in 2009 to four clusters in 2010, the number of clusters increased to eight in 2011. The number of WPV3 clusters declined from 21 in 2009 to six in 2010 and to four in 2011. Genomic sequence analysis shows much less genetic linkage than expected with sensitive AFP surveillance, including some chains of WPV transmission during 2011–2012 not detected for more than a year. The proportion of WPV and cVDPV2 isolates (from cases and contacts) with less than expected genetic linkage (>98.5%) was 60% (29 of 48) in 2010, 31% (30 of 98) in 2011, and 16% (16 of 103) to date in 2012.

Reported by

National Primary Health Care Development Agency and Federal Ministry of Health; World Health Organization Country Office, Abuja; Poliovirus Laboratory, Univ of Ibadan, Ibadan; Poliovirus Laboratory, Univ of Maiduguri Teaching Hospital, Maiduguri, Nigeria. African Regional Polio Reference Laboratory, National Institute for Communicable Diseases, Johannesburg, South Africa. Immunization and Vaccine Development, World Health Organization Regional Office for Africa, Brazzaville, Congo; Polio Eradication Dept, World Health Organization, Geneva, Switzerland. Div of Viral Diseases, National Center for Immunization and Respiratory Diseases; Global Immunization Div, Center for Global Health, CDC. Corresponding contributor: Stacie Dunkle, Global Immunization Div, Center for Global Health, CDC; sdunkle@cdc.gov; 404-861-4841.

Editorial Note

Indigenous WPV1 and WPV3 transmission has continued in the northern states of Nigeria because of long-standing weaknesses in health system infrastructure, programmatic limitations in the planning and implementation of SIAs, and insufficient accountability, compounded by low public confidence in OPV since 2003 in some communities (10). By 2009, substantial progress in implementation of polio eradication activities (attributed to enhanced collaboration with traditional, religious, and political leaders) was followed by a sharp decline in cases; however, a substantial proportion of children, including each newborn cohort, remained chronically unvaccinated or undervaccinated. As WPV continues to circulate in multiple "sanctuaries"§§ in northern states (7), WPV1 and WPV3 cases have increased since 2010, with cases occurring in a growing number of LGAs. Only 17 WPV3 cases were reported in Nigeria during January–September 2012, but WPV3 strains in Nigeria are more genetically diverse than WPV3 strains in Pakistan, the only other country with circulating WPV3 in 2012 (4). Cases of cVDPV2 have declined in 2012; however, extensive cVDPV2 circulation continues to be detected by environmental surveillance in Sokoto.

Although subnational AFP surveillance indicators generally are being met and sequence analysis suggests some improvement in sensitivity over time, environmental surveillance and genomic sequence evidence indicate that substantial surveillance gaps persist (5,9); these gaps might result from variability in AFP surveillance sensitivity at the LGA level or within population subgroups. Key challenges to achieving the high routine and supplementary vaccination coverage that is required to eliminate poliovirus transmission in Nigeria remain and have been compounded by insecurity in some states since late 2011. To address these challenges, the Nigeria 2012 Polio Eradication Emergency Plan (6) includes new initiatives to enhance high-level political oversight and improve program management and accountability, and provides for the deployment of a surge in human resources by government and partner organizations (primarily the World Health Organization and the United Nations Children's Fund) in high-risk states, down to the lowest administrative levels (wards). The augmented technical staff is implementing new strategies to reach chronically missed children during SIAs; these include the use of revised, detailed, and extensively validated house-to-house SIA microplans, more rigorous selection and training of vaccinators, revision of the size and composition of vaccination teams, and increased attention to the identification and vaccination of nomadic and other vulnerable populations. In some states, satellite mapping improved the demarcation of LGA, ward, and team boundaries and identified previously missed settlements. Volunteer community mobilizers have been deployed to settlements with historically high vaccination refusal rates. Insecurity in some LGAs in Borno and Yobe states creates difficulties in reaching undervaccinated children; addressing this will require enhanced engagement of affected communities.

A Nigerian presidential task force was established in March 2012 to provide leadership and oversight of state and local task forces and to improve local accountability for implementation of SIAs. An accountability "dashboard" tool¶¶ has been developed and implemented for monitoring SIA preparations and execution at the LGA level. In addition, experienced Indian surveillance medical officers and a National Stop Transmission of Polio program of health professionals have been deployed to support the development of sustainable management capacity in high-risk LGAs. Efforts continue to identify and include nomadic and otherwise vulnerable children in current microplans, strengthen SIA supervision, and enhance community awareness and availability of routine vaccination through outreach services. The epidemiologic impact of the recent implementation of the Polio Eradication Emergency Plan has yet to be observed; however, improvements in SIA coverage are establishing a stronger footing for measurable progress in 2013. If WPV case counts and extent of circulation are not reduced substantially by mid-2013, additional innovative vaccination strategies to interrupt all WPV transmission will need to be considered. Ongoing WPV transmission in northern Nigeria remains a threat for reintroduction into southern Nigeria and surrounding polio-free countries in Africa, and is a major obstacle to success of GPEI (7).

References

  1. World Health Assembly. Poliomyelitis: intensification of the global eradication initiative. Resolution WHA65.5. Geneva, Switzerland: World Health Organization; 2012. Available at http://apps.who.int/gb/ebwha/pdf_files/wha65/a65_r5-en.pdf  . Accessed November 7, 2012
  2. CDC. Progress toward global polio eradication—Africa, 2011. MMWR 2012;61:190–4.
  3. CDC. Progress toward interruption of wild poliovirus transmission—worldwide, January 2011–March 2012. MMWR 2012;61:353–7.
  4. CDC. Progress toward poliomyelitis eradication—Afghanistan and Pakistan, January 2011–August 2012. MMWR 2012;61:790–5.
  5. CDC. Progress toward poliomyelitis eradication—Nigeria, January 2010–June 2011. MMWR 2011;60:1053–7.
  6. National Primary Health Care Agency. Nigeria Polio Eradication Emergency Plan, 2012. Annex 2 of the Global Polio Eradication Emergency Action Plan 2012–2013. World Health Organization: Geneva, Switzerland; 2012. Available at http://www.polioeradication.org/portals/0/document/aboutus/governance/imb/6imbmeeting/7.5_6imb.pdf  . Accessed November 1, 2012.
  7. Independent Monitoring Board of the Global Polio Eradication Initiative. Every missed child: report of the Independent Monitoring Board of the Global Polio Eradication Initiative. Geneva, Switzerland: World Health Organization; 2012. Available at http://www.polioeradication.org/portals/0/document/aboutus/governance/imb/6imbmeeting/imb6_report.pdf  . Accessed November 1, 2012.
  8. World Health Organization. WHO vaccine-preventable diseases monitoring system: 2012 global summary. Geneva, Switzerland: World Health Organization; 2012. Available at http://www.who.int/vaccines/globalsummary/immunization/countryprofileselect.cfm . Accessed November 1, 2012.
  9. CDC. Tracking progress toward global polio eradication, 2010–2011. MMWR 2012;61:265–9.

10.  CDC. Progress toward poliomyelitis eradication—Nigeria, January 2004–July 2005. MMWR 2005;54:873–7.

 

* Mass campaigns conducted for a brief period (days to weeks) in which 1 dose of oral poliovirus vaccine is administered to all children aged <5 years, regardless of vaccination history. Campaigns can be conducted nationally or in sections of the country.

† Additional information available at http://www.measuredhs.com/pubs/pdf/sr173/sr173.pdf  .

§ A sample of 10 children aged <5 years was selected from each of six randomly selected wards within local government areas. The <20% missed children threshold is defined as eight or fewer of these 60 children not being vaccinated in the most recent SIA.

¶ Preliminary results from lot quality-assurance sampling after an SIA in northern states in October 2012 demonstrate an additional decline in the proportion of LGAs failing to meet the <20% missed children threshold (63 of 134 [47%]).

** Adequate stool specimen collection is defined as two specimens collected at least 24 hours apart, both within 14 days of paralysis onset, and shipped on ice or frozen packs to a World Health Organization–accredited laboratory, arriving in good condition.

†† All isolates are sequenced across the interval encoding the major capsid protein (VP1) (approximately 900 nucleotides), and results are analyzed to determine the likely origin (by state and local government area) of the virus. Isolates within a cluster share >95% VP1 nucleotide sequence identity.

§§ Discrete geographic locations with large numbers of missed children where the virus has ample opportunity to circulate.

¶¶ An interactive, visual presentation of the current status and historical trends of data. In this case, the data represent LGA-level information on key pre-, intra-, and post-SIA indicators to allow for course-correcting decision making at the state and national levels.

 

What is already known on this topic?

Nigeria is one of three countries, including Afghanistan and Pakistan, where wild poliovirus (WPV) transmission has never been interrupted. Long-standing weaknesses in health system infrastructure, programmatic limitations in implementation of vaccination campaigns, weak accountability mechanisms, and a loss of public confidence in oral poliovirus vaccine since 2003 in some areas have contributed to ongoing circulation.

What is added by this report?

The number of WPV cases in northern Nigeria nearly tripled in 2011 compared with 2010, and more than doubled in the first 9 months of 2012 compared with the same period in 2011. In addition, transmission of circulating vaccine-derived polio virus type 2 continues. Nigeria's 2012 Polio Eradication Emergency Plan includes new program management and accountability initiatives along with a surge in human resources to vaccinate repeatedly missed children. Indicators of the quality of vaccination campaigns show modest improvements in 2012; routine vaccination coverage continues to be low. Despite national and state-level acute flaccid paralysis surveillance indicators generally being met, available data indicate continued gaps in surveillance.

What are the implications for public health practice?

Continuing WPV transmission in Nigeria poses an ongoing risk for WPV reintroduction into polio-free countries and is a major obstacle to the success of global eradication. Recent initiatives by government and partners have yet to demonstrate their impact epidemiologically, but indicate promise. If WPV case counts and extent of circulation are not reduced substantially by mid-2013, additional innovative strategies to interrupt WPV transmission might need to be considered.

 

  • PARENTAL PERCEPTIONS OF POLIO IN KARACHI

 

Bulletin of the World Health Organization

Parental perceptions surrounding polio and self-reported non-participation in polio supplementary immunization activities in Karachi, Pakistan: a mixed methods study

Asif Raza Khowaja a, Sher Ali Khan a, Naveeda Nizam a, Saad Bin Omer b & Anita Zaidi a

a. Aga Khan University, Stadium Road, PO Box 3500, Karachi, 74800, Pakistan.
b. Schools of Public Health and Medicine, Emory University, Atlanta, United States of America.

Correspondence to Anita Zaidi (e-mail: anita.zaidi@aku.edu).

(Submitted: 14 April 2012 – Revised version received: 22 August 2012 – Accepted: 23 August 2012 – Published online: 14 September 2012.)

Bulletin of the World Health Organization 2012;90:822-830. doi: 10.2471/BLT.12.106260

Full text is at

 http://www.who.int/bulletin/volumes/90/11/12-106260/en/index.html

Introduction

Pakistan is one of only three endemic countries in the world still struggling to interrupt poliovirus transmission and meet the target of global polio eradication by 2012. Polio supplementary immunization activities (SIAs) for the home delivery of oral polio vaccine (OPV) were initiated in the country in 2000, when 119 cases of polio were reported. Although the number of cases declined to 32 in 2007, it has been rising steadily since 2008.1 In 2011 Pakistan reported the world’s highest number of polio cases and some fear the country may become the last remaining host of polio on earth. The situation clearly poses a serious threat to the Global Polio Eradication Initiative (GPEI).2–4 In Pakistan, elimination efforts have largely relied on a robust case detection system based on surveillance of acute flaccid paralysis cases and on mass door-to-door polio SIAs, of which more than 100 have been conducted since the year 2000.5,6 Every child less than 5 years of age who resides in Pakistan has to be reached during each SIA, since multiple doses of OPV are needed in countries with high endemicity for children to develop adequate immunity against polio.1-4 SIAs can vary in frequency but are usually held one to two months apart.

SIAs against polio are primarily organized by government officials with support from United Nations partners, mainly the World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF). SIAs are intended to complement, not replace, routine immunization against polio. They aim to interrupt poliovirus circulation through administration of the oral polio vaccine (OPV) to every child aged < 5 years in every vaccine SIA campaign, irrespective of immunization history.7 Public announcements through media coverage, posters and banners are used to create awareness about upcoming polio SIAs and encourage participation. Social marketing and community mobilization efforts are organized by UNICEF, and the staff of WHO’s Polio Eradication Initiative assist local health officials in organizing, implementing and monitoring SIAs. A large cadre of vaccinators, health workers and community volunteers administer OPV to eligible children through visits to all households and at fixed health facilities.7,8

Although high coverage (> 90%) during polio SIAs has been reported in Pakistan, actual coverage is questionable. An official report of the Independent Monitoring Board of the Global Polio Eradication Initiative published in February 2012 highlighted major planning and execution gaps for polio SIAs in Pakistan.3 Several factors have made the goal of eliminating polio in Pakistan elusive. These include inconsistent quality of SIAs; failure to immunize children in many areas; inaccessibility of children due to ongoing military conflict; massive floods; poor routine immunization services; a structurally weak polio eradication programme; large nomadic and internally-displaced populations, and the refusal of some parents to have their children vaccinated.9,10 Many of these factors have led to the clustering of unimmunized children, who are at high risk of getting polio.11

Very few studies evaluating the results of polio SIAs in Karachi have been published. We chose Karachi for our study because polio is endemic in the city and the risk of transmission is among the highest in Pakistan. Karachi is, in fact, the only megacity in the world that has not yet succeeded in interrupting polio transmission. Besides, its population represents all ethnic groups in Pakistan. Given Karachi’s large cultural and ethnic diversity, we studied a large representative sample of individuals living across the city, our objective being to assess parents’ knowledge about polio, rates of non-participation in polio SIAs and reasons for non-participation. We ensured adequate representation of the Pashtun community, a group that comprises an estimated 35–40% of Karachi’s population and yet has suffered 90% of recent polio cases in the city. This community has high rates of migration and displacement and low rates of polio vaccination.12

Methods

Data collection for our study, which had a mixed methods design, was completed in three months (November 2011to January 2012). The quantitative component of the study involved a cross-sectional cluster survey in Karachi, a megacity comprising 18 towns, 1 cantonment and 178 localities known as union councils.13 The sampling frame, developed for our previous vaccine research, consisted of 90 randomly selected clusters with a total population of 200 000 and between 200 and 250 households each. The sample was sociodemographically representative of the entire population of Karachi.14 From this sampling frame we selected 60 clusters of low- and middle-income households. Using the probability proportionate to size technique, we calculated the number of households we would need to survey within each cluster. Table 1 shows the 18 towns and one cantonment area that make up Karachi and the number and fraction of households sampled in each town.

In our previous work we had difficulty accessing households in affluent areas of Karachi because of tight security measures. For this reason, in the current study we selected five large shopping malls as sites for approaching and interviewing the members of affluent families from different high-income areas of the city. In total, 153 eligible families – approximately 15% of the proportionally representative sampling frame – were interviewed in malls. We posed no income- or asset-related questions to avoid affecting the response rate, but these malls, considered safe, have reserved rights of admission and are visited by affluent families for entertainment and shopping. Thus, people who frequent them are broadly representative of the upper classes.

We estimated the sample size using the formula for cross-sectional prevalence studies; we assumed a 30% rate of non-participation in polio SIAs, a 5% non-response rate, a 5% margin of error and a design effect of 2.0 for cluster sampling. We inflated the resulting sample size, 646, by 50% to ensure a large enough sampling of Pashtun households to allow us to evaluate any differences among ethnic groups in lack of participation in polio SIAs. This yielded a final sample of 1001 households.

Parents were eligible to participate in the survey if they were residents of Karachi and had children aged < 5 years in their household. Verbal consent was obtained from all parents who participated in the survey. We developed a structured questionnaire and pilot tested it in households drawn from neighbouring clusters. The questionnaire included questions on demographics, knowledge about the symptoms of polio, and number of polio SIAs in which parents had participated in the two most recent months. Two SIAs were held in Karachi (September and October 2011) just before the survey. To select the households to be surveyed, trained project staff (research assistants and field workers) spun a bottle in the main street of each town to choose the direction in which to approach the first household and then used systematic random sampling with a skip pattern of two after each eligible dwelling to select the remaining households. Any parent available (mother or father of a child < 5 years old) was interviewed. In shopping malls, research assistants invited families to participate in the survey if they reported having children aged < 5 years and living in a high-income part of the city (Defence Housing Authority, Clifton, Gulshan-e-Iqbal and North Nazimabad). A senior research assistant made spot-check visits to homes and malls and re-interviewed 5% of the respondents to ensure the quality of data collection.

For the qualitative assessment, parents who refused to have their children receive the OPV or who reported that their eligible children did not participate in the two most recent polio SIAs were purposively selected from the Pashtun population and invited for in-depth interviews. Only ethnic Pashtuns were interviewed because migration and displacement are common among them and their children have the highest rate of confirmed cases of polio in Pakistan and the highest risk among all ethnic groups. Only fathers were interviewed because they are the main decision-makers in Pashtun families. A native Pashto-speaking male medical student (SAK in his final year was trained to conduct these interviews. Data saturation was reached after 30 in-depth interviews. Written notes were transcribed and thematic analysis was conducted on emerging themes surrounding the reasons for children not having received or having refused to receive the OPV. The survey data were entered electronically in real time and analysed on SPSS version 19 (SPSS Inc., Chicago, United States of America).

Descriptive analysis was performed and proportions were compared for three groups: (i) low-income Pashtun families; (ii) low-income families of other ethnicities (non-Pashtun); and (iii) middle- and high-income families of any ethnic background. Income group was based on area of residence (Table 1). Differences between these groups in terms of knowledge about polio, participation in SIAs and reasons for non-participation are expressed as odds ratios (ORs) with 95% confidence intervals (CIs). This study received ethical approval from the ethics review committee of Aga Khan University in Karachi.

Results

A total of 2149 parents were approached at households in the community and shopping malls, and 1116 were found eligible to participate in the study. Among eligible parents, 51 (5.6%) and 48 (24%) refused to participate in households and at malls, respectively (Fig. 1). Of the 1017 parents who agreed to participate, about 90% were mothers of the children aged < 5 years; 441 (43.4%), 423 (41.6%) and 153 (15%) of the respective families were categorized as low-income Pashtun, low-income non-Pashtun, or middle- or high-income, regardless of ethnic background.

Fig. 1. Flowchart of participants in study of parental knowledge and perceptions surrounding polio and of participation in polio vaccine supplementary immunization activities in Karachi, Pakistan, 2011

 

The children were 3.2 years old on average (standard deviation, SD: ± 1.5); 52% were male and 48% were female. Of the parents interviewed, 412 (40.5%) reported never having heard about “polio disease” (Table 2) and 246 (24%) reported not having heard about recent polio SIAs in their area in 2011; of parents in this last group, 193 (78% of the parents interviewed) belonged to low-income Pashtun households. Only 728 (72%) parents reported that their children had participated in both the September and October polio SIAs; 157 (15.4%) reported that their children had not participated in either SIA. There were 34 (21.6%) parents who reported having had no contact with a vaccinator in their home, 116 (73.9%) reported having refused the vaccination and 7 (4.5%) said that their child was not at home when the vaccinator had visited (Table 3). Refusals clustered in low-income Pashtun (43/441; 9.8%) and high-income (71/153; 46.4%) populations, whereas low- and middle-income non-Pashtun populations had high rates of SIA participation, with only 2% (9/423) having received no dose of OPV in both polio SIA campaigns. Pashtun parents stated as the primary reasons for refusing to have their children vaccinated fear of potential harm from the OPV (16%) and lack of permission from family elders (77%). Among high-income respondents interviewed in malls, the main reason given was the belief that the vaccine was harmful (72%) or unnecessary (8.5%) (Table 4). Vaccine refusal rates in the 18 towns and one cantonment of Karachi ranged between 0% and 70%, with the highest refusal rates reported from the high-income areas of Defence Housing Authority and Clifton (Table 1).

Significant differences in knowledge about polio and in participation in SIAs were observed between low-income Pashtuns and low-income non-Pashtuns (Table 5). The odds of knowing nothing about polio were 2.2 (95% CI: 1.1–4.3) times greater among low-income Pashtun parents than among low-income non-Pashtuns (Table 5). Low-income Pashtun parents were 6 times (95% CI: 4.3–8.8) more likely to have never heard about a polio SIA campaign in their area than low-income non-Pashtuns. Moreover, children of low-income Pashtun parents were 7 times (95% CI: 3.5–14.5) more likely to have failed to participate in polio SIAs than children of low-income non-Pashtun parents.

Qualitative analysis

In-depth interviews revealed parental perceptions surrounding polio and polio vaccination and why some children did not received the OPV during the two most recent polio SIAs. Most of the parents thought that the polio vaccine caused sterility in adulthood. Some also considered polio vaccination campaigns to be part of a conspiracy against Muslim nations, including Pakistan. “Polio vaccine is prepared in the West and sent here. It is then given to our children in order to destroy their ability to reproduce in the future.” Moreover, about one third of the parents reported “no belief” in the polio vaccine and considered it useless or ineffective against polio. “It is of no good, because one of my friends has polio even though he was vaccinated against it.” Other parents felt that since their children had received several doses of polio vaccine in the past, they did not need to get vaccinated again. Some voiced doubts about the government’s “disguised policy” of conducting exhaustive efforts against polio. “Why do the government and health system give so much emphasis to polio vaccine? There are so many other diseases that should be addressed first. There must be some other reason (negative reason) for their giving so much importance to polio vaccine.” Another important theme was concern that the vaccine could contain religiously forbidden “non-halal” ingredients. “I was allowing my children to receive polio vaccine until last year, when I learnt that the material used is un-Islamic (haraam)…. if we are given proof that this material is not haraam, then we will allow our children for polio vaccine.” A few parents also mentioned other reasons, including a bad cold chain, difficulty in communicating with the polio vaccinator because of a language barrier and fear of side-effects (fever, bloating of skin, weakness, etc.).

Discussion

In Karachi, parental refusal was the most common reason given for the failure of children to participate in the two most recent polio vaccine SIAs. It accounted for non-participation in 74% of the cases. A clustering of vaccine refusals among ethnic low-income Pashtun and high-income populations was noted and varied by town. Lack of knowledge about polio, lack of faith in the vaccine’s effectiveness, misperceptions about vaccine-related adverse events (e.g. infertility) and mistrust among Pashtuns make it highly likely that poliovirus transmission will continue in this population unless specific targeted activities are undertaken to promote vaccination.

Our overall findings pertaining to why some parents refuse to have their children vaccinated are in line with those of previous studies that have identified misperceptions regarding disease susceptibility and vaccine efficacy and concerns about safety.15,16 Moreover, lack of trust in vaccines and in those who deliver them (e.g. health-care providers, governments and international agencies) has been identified as an important hindrance to routine OPV immunization and polio elimination.17,18

This study was undertaken in the wake of extensive media reports of an allegedly fake vaccination campaign organized by the United States Central Intelligence Agency to try to track down Osama Bin Laden by surreptitiously obtaining blood samples from his family members for deoxyribonucleic acid (DNA) testing. The campaign was run by a Pashtun government physician from the tribal area of Khyber Agency who had worked in polio vaccine campaigns.19,20 Although we prudently avoided explicit references to this in our in-depth interviews, several Pashtun families gave distrust of government-run programmes as the reason for having refused to get their children vaccinated. The publicity surrounding the bogus vaccination campaign is probably not the only reason for people’s mistrust of the polio vaccine, since vaccine refusals had been documented in the Pashtun population even before the incident. However, reports of the incident may have reinforced or perpetuated negative perceptions. The long-term impact of this incident on polio eradication efforts in Pakistan remains to be determined.

At the community level, conventional communication efforts surrounding polio are largely conducted by female workers or mobilizers who primarily target adult females in the households.21 Male family decision-makers or community and religious leaders are insufficiently engaged and are usually absent during the day time when vaccinators visit households.22 In Pashtun populations in particular males are the primary decision-makers. They have strong religious beliefs and are key to polio eradication efforts. Our interviews showed that religious authorities of two or three of the main religious institutions (madrassahs) heavily influence the opinions of Pashtun men in Karachi. To enhance social mobilization, integrated participatory interventions targeting communities at high risk for polio need to be implemented.23,24 These interventions should include parental counselling, targeted particularly at male decision-makers; the creation of community networks involving trusted religious authorities, and role modelling by parents who approve of the polio vaccine. The strategy of involving religious opinion leaders in efforts to increase acceptance of polio immunization has already been employed in northern India and Nigeria.11,25 More formative and evaluative research is needed to identify the most effective strategies.

A high proportion (24%) of eligible high-income families declined to participate in the survey at malls primarily because of “lack of time”. Worth noting is the fact that vaccination refusal rates were high among those who did participate in the survey. The upper class has little trust in government services and seeks health care and immunization services in the private sector. Evidence suggests that the high-income population is adequately immunized and that most children in this group have received injectable and oral polio vaccines through private paediatric practices (Zaidi AK, unpublished data). Although children from high-income families are at little risk of contracting polio, the widespread belief in this social group that repeat doses of OPV are harmful may undermine the overall success of the polio eradication programme, since the wealthy are often opinion leaders and trendsetters.26–28

This is the first study to identify the main perceptions associated with lack of participation in polio SIAs in the ethnic group with the highest polio incidence in Pakistan. This high-risk group needs targeted educational messages and we believe that our findings will contribute to their development. Operational research on increasing polio vaccine acceptance by offering packages of health and non-health interventions during polio SIA campaigns should also be explored.

Although our study was conducted in Karachi, some findings may be generalizable to other parts of Pakistan that are important for polio eradication efforts, since outside Karachi endemic polio transmission is primarily restricted to Pashtun majority areas.

Competing interests:

None declared.

References

  • THE EFFECT OF MASS IMMUNISATION CAMPAIGNS AND NEW ORAL POLIOVIRUS VACCINES ON THE INCIDENCE OF POLIOMYELITIS IN PAKISTAN AND AFGHANISTAN, 2001—11: A RETROSPECTIVE ANALYSIS

Original Text

Dr Kathleen M O'Reilly PhD a , Elias Durry MD b, Obaid ul Islam MBBS b, Arshad Quddus MSc c, Ni'ma Abid FICM b, Tahir P Mir MPH d, Rudi H Tangermann MD e, R Bruce Aylward MD e, Nicholas C Grassly DPhil a

 

The Lancet, Volume 380, Issue 9840, Pages 491 - 498, 4 August 2012

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Published Online: 04 July 2012

Full text is at

http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)60648-5/fulltext

Summary

Background

Pakistan and Afghanistan are two of the three remaining countries yet to interrupt wild-type poliovirus transmission. The increasing incidence of poliomyelitis in these countries during 2010—11 led the Executive Board of WHO in January, 2012, to declare polio eradication a “programmatic emergency for global public health”. We aimed to establish why incidence is rising in these countries despite programme innovations including the introduction of new vaccines.

Methods

We did a matched case-control analysis based on a database of 46 977 children aged 0—14 years with onset of acute flaccid paralysis between Jan 1, 2001, and Dec 31, 2011. The vaccination history of children with poliomyelitis was compared with that of children with acute flaccid paralysis due to other causes to estimate the clinical effectiveness of oral poliovirus vaccines (OPVs) in Afghanistan and Pakistan by conditional logistic regression. We estimated vaccine coverage and serotype-specific vaccine-induced population immunity in children aged 0—2 years and assessed their association with the incidence of poliomyelitis over time in seven regions of Afghanistan and Pakistan.

Findings

Between Jan 1, 2001, and Dec 31, 2011, there were 883 cases of serotype 1 poliomyelitis (710 in Pakistan and 173 in Afghanistan) and 272 cases of poliomyelitis serotype 3 (216 in Pakistan and 56 in Afghanistan). The estimated clinical effectiveness of a dose of trivalent OPV against serotype 1 poliomyelitis was 12·5% (95% CI 5·6—18·8) compared with 34·5% (16·1—48·9) for monovalent OPV (p=0·007) and 23·4% (10·4—34·6) for bivalent OPV (p=0·067). Bivalent OPV was non-inferior compared with monovalent OPV (p=0·21). Vaccination coverage decreased during 2006—11 in the Federally Administered Tribal Areas (FATA), Balochistan, and Khyber Pakhtunkhwa in Pakistan and in southern Afghanistan. Although partially mitigated by the use of more effective vaccines, these decreases in coverage resulted in lower vaccine-induced population immunity to poliovirus serotype 1 in FATA and Balochistan and associated increases in the incidence of poliomyelitis.

Interpretation

The effectiveness of bivalent OPV is comparable with monovalent OPV and can therefore be used in eradicating serotype 1 poliomyelitis whilst minimising the risks of serotype 3 outbreaks. However, decreases in vaccination coverage in parts of Pakistan and southern Afghanistan have severely limited the effect of this vaccine.

Funding

Poliovirus Research subcommittee of WHO, Royal Society, and Medical Research Council.

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