Supplementary polio immunization activities and prior use of routine immunization services in non-polio-endemic sub-Saharan Africa

Coverage and factors associated with receiving campaign polio vaccines in an urban population in Guinea-Bissau

BACKGROUND

Polio eradication campaigns are intended to complement routine immunization. Studies addressing factors associated with campaign coverage are warranted to identify children missed by campaigns.

METHODS

Bandim Health Project runs demographic surveillance with registration of routine immunization and campaign participation data in urban Guinea-Bissau. We assessed coverage and factors associated with receiving campaign polio vaccines in children aged 0-35 months in two polio eradication campaigns conducted in 2017 and 2018 using univariate and multivariate regression models.

RESULTS

Campaign coverage reached 84% in 2017 and 88% in 2018. We found lower coverage among children of young and not formally educated mothers in univariate analyses; Children <9 months and Fula children had lower campaign coverage in both univariate and multivariate analyses.

CONCLUSIONS

To increase campaign coverage in urban Guinea-Bissau attention may be directed at informing young mothers, mothers of young children, mothers without formal education, and the Fula ethnic group about campaigns.

The Potential Contribution of Supplementary Immunization Activities to Routine Immunization in Kebbi State, Nigeria

Background: Among the strategies of the Polio Eradication Initiative, the landmark interventions are routine immunization (RI) and supplementary immunization activities (SIAs). RI is the provision of vaccination service at the health facility and conducted year-round. SIAs are a community-based intervention targeting large numbers of an eligible population within a short period. Hence, the study aimed to assess the contributions of SIAs on access and utilization of RI services. Methods: We conducted the study in 10 local government areas in Kebbi State, northwestern Nigeria. We analyzed RI data from January to September 2019 and included the 4 SIAs conducted in January, April, August, and September in the same years. The number of children vaccinated, the trend of BCG, pentavalent vaccine at 6 and 10 weeks, and measles coverage and dropout rates (DORs) were analyzed. Results: For all the selected vaccines, the highest contributions to RI were recorded during the August 2019 fractional Inactivated Polio Vaccine (fIPV) campaign. On the other hand, the least contributions were noted during January SIAs. The BCG coverage showed an erratic trend with the lowest in February and highest in July 2019. The coverage for the pentavalent vaccine at 6 and 10 weeks was lowest in February and September. The pentavalent vaccine DOR pattern showed the lowest in February with value of 0% and the highest in June with 12%. Except for May and June, the Pentavalent vaccine DORs for all other months were <10%. February 2019 had the lowest measles coverage. Conclusion: Our study demonstrated that the integration of RI into SIAs could improve RI coverage. and potentially reduce DOR, especially when the integration is of good quality and conducted at short and regular intervals. Although SIAs are instrumental at increasing RI coverage, the disruption of RI services may occur due to overlapping resources and poor planning. Therefore, SIAs should be adequately planned by program managers to strengthen RI service delivery during the SIAs implementation.

Switching vaccination among target groups to achieve improved long-lasting benefits

The development of vaccines has opened a way to lower the public health and societal burden of COVID-19 pandemic. To achieve sustainable gains in the long term, switching the vaccination from one target group to a more diverse portfolio should be planned appropriately. We lay out a general mathematical framework for comparing alternative vaccination roll-out strategies for the year to come: single focus groups: (i-a) the high-risk older age groups and (i-b) the core-sociable groups; and two focus groups: (ii-a) mixed vaccination of both the high-risk and core-sociable groups simultaneously and (ii-b) cyclic vaccination switching between groups. Featuring analyses of all relevant data including age pyramids for 15 representative countries with diverse social mixing patterns shows that mixed strategies that result in both direct and indirect protection of high-risk groups may be better for the overall societal health impact of COVID-19 vaccine roll-out. Of note, over time switching the priority from high-risk older age groups to core-sociable groups responsible for heightened circulation and thus indirect risk may be increasingly advantageous.

Field investigation and response to a vaccine-derived poliovirus pre-tOPV switch in Southwest Nigeria, October 2015

A vaccine-derived poliovirus (VDPV) was isolated in an acute flaccid paralysis (AFP) case reported from Ile-Ife, in Osun state, Southwest Nigeria. We investigated the epidemiological characteristics of the polio event and described the immediate public health response that followed. We interviewed the primary caregiver of the case and conducted active case searches for additional AFP cases in the communities in Ife East Local Government Area (LGA) of Osun state. Stool samples of contacts and non-contacts were collected and sent for laboratory investigation. A public health response with mass supplementary immunization in the affected areas followed immediately in the ward the case was located in October 2015. Also, we reviewed the administrative record of the oral polio vaccine (OPV) coverage in the LGA in the previous four years. The VDPV case was a female, one-month-old child with adequate vaccination history for her age. However, the environment of the child was relatively filthy with inappropriate facilities. Laboratory reports from contact samples were negative for VDPV or any polio isolates. A missed AFP case was found from active case searches and a high proportion of under-five children was immunized with tOPV. The OPV3 administrative coverage in the LGA peaked in 2014 (103%) and dropped in 2015 (67%). Efforts directed toward improving environmental hygiene in households and improving OPV coverage in subsequent routine and supplementary immunization are suggested.

Mapping vaccination coverage to explore the effects of delivery mechanisms and inform vaccination strategies

The success of vaccination programs depends largely on the mechanisms used in vaccine delivery. National immunization programs offer childhood vaccines through fixed and outreach services within the health system and often, additional supplementary immunization activities (SIAs) are undertaken to fill gaps and boost coverage. Here, we map predicted coverage at 1 × 1 km spatial resolution in five low- and middle-income countries to identify areas that are under-vaccinated via each delivery method using Demographic and Health Surveys data. We compare estimates of the coverage of the third dose of diphtheria-tetanus-pertussis-containing vaccine (DTP3), which is typically delivered through routine immunization (RI), with those of measles-containing vaccine (MCV) for which SIAs are also undertaken. We find that SIAs have boosted MCV coverage in some places, but not in others, particularly where RI had been deficient, as depicted by DTP coverage. The modelling approaches outlined here can help to guide geographical prioritization and strategy design.

Comparative epidemiology of poliovirus transmission

Understanding the determinants of polio transmission and its large-scale epidemiology remains a public health priority. Despite a 99% reduction in annual wild poliovirus (WPV) cases since 1988, tackling the last 1% has proven difficult. We identified key covariates of geographical variation in polio transmission patterns by relating country-specific annual disease incidence to demographic, socio-economic and environmental factors. We assessed the relative contributions of these variables to the performance of computer-generated models for predicting polio transmission. We also examined the effect of spatial coupling on the polio extinction frequency in islands relative to larger land masses. Access to sanitation, population density, forest cover and routine vaccination coverage were the strongest predictors of polio incidence, however their relative effect sizes were inconsistent geographically. The effect of climate variables on polio incidence was negligible, indicating that a climate effect is not identifiable at the annual scale, suggesting a role for climate in shaping the transmission seasonality rather than intensity. We found polio fadeout frequency to depend on both population size and demography, which should therefore be considered in policies aimed at extinction. Our comparative epidemiological approach highlights the heterogeneity among polio transmission determinants. Recognition of this variation is important for the maintenance of population immunity in a post-polio era.

Effects of polio eradication activities on routine immunization: lessons from the 2013 outbreak response in Somali region of Ethiopia

Introduction

Ethiopia experienced several WPV importations with a total of 10 WPV1 cases confirmed during the 2013 outbreak alone before it is closed in 2015. We evaluated supplemental immunization activities (SIAs), including lessons learned for their effect on the routine immunization program during the 2013 polio outbreak in Somali regional state.

Methods

We used descriptive study to review documents and analyse routine health information system reports from the polio outbreak affected Somali regional state.

Results

All data and technical reports of the 15 rounds of polio SIAs from June 2013 through June 2015 and routine immunization coverages for DPT-Hib-HepB 3 and measles were observed. More than 93% of the SIAs were having administrative coverage above 95%. The trend of routine immunization for the two antigens, over the five years (2011 through 2015) did not show a consistent pattern against the number of SIAs. Documentations showed qualitative positive impacts of the SIAs strengthening the routine immunization during all courses of the campaigns.

Conclusion

The quantitative impact of polio SIAs on routine immunization remained not so impressive in this study. Clear planning, data consistencies and completeness issues need to be cleared for the impact assessment in quantitative terms, in polio legacy planning as well as for the introduction of injectable polio vaccine through the routine immunization.

A review of measles supplementary immunization activities and the implications for Pacific Island countries and territories

INTRODUCTION

Standard measles control strategies include achieving high levels of measles vaccine coverage using routine delivery systems, supplemented by mass immunization campaigns as needed to close population immunity gaps. Areas covered: This review looks at how supplementary immunization activities (SIAs) have contributed to measles control globally, and asks whether such a strategy has a place in Pacific Islands today. Expert commentary: Very high coverage with two doses of measles vaccine seems to be the optimal strategy for controlling measles. By 2015, all but two Pacific Islands had introduced a second dose in the routine schedule; however, a number of countries have not yet reached high coverage with their second dose. The literature and the country reviews reported here suggest that a high coverage SIA combined with one dose of measles vaccine given in the routine system will also do the job. The arguments for and against the use of SIAs are complex, but it is clear that to be effective, SIAs need to be well designed to meet specific needs, must be carried out effectively and safely with very high coverage, and should, when possible, carry with them other public health interventions to make them even more cost-effective.

Contribution of polio eradication initiative to strengthening routine immunization: Lessons learnt in the WHO African region

BACKGROUND

Important investments were made in countries for the polio eradication initiative. On 25 September 2015, a major milestone was achieved when Nigeria was removed from the list of polio-endemic countries. Routine Immunization, being a key pillar of polio eradication initiative needs to be strengthened to sustain the gains made in countries. For this, there is a huge potential on building on the use of polio infrastructure to contribute to RI strengthening.

METHODS

We reviewed estimates of immunization coverage as reported by the countries to WHO and UNICEF for three vaccines: BCG, DTP3 (third dose of diphtheria-tetanus toxoid- pertussis), and the first dose of measles-containing vaccine (MCV1).We conducted a systematic review of best practices documents from eight countries which had significant polio eradication activities.

RESULTS

Immunization programmes have improved significantly in the African Region. Regional coverage for DTP3 vaccine increased from 51% in 1996 to 77% in 2014. DTP3 coverage increased >3 folds in DRC (18-80%) and Nigeria from 21% to 66%; and >2 folds in Angola (41-87%), Chad (24-46%), and Togo (42-87%). Coverage for BCG and MCV1 increased in all countries. Of the 47 countries in the region, 18 (38%) achieved a national coverage for DTP3 ⩾90% for 2years meeting the Global Vaccine Action (GVAP) target. A decrease was noted in the Ebola-affected countries i.e., Guinea, Liberia and Sierra Leone.

CONCLUSIONS

PEI has been associated with increased spending on immunization and the related improvements, especially in the areas of micro planning, service delivery, program management and capacity building. Continued efforts are needed to mobilize international and domestic support to strengthen and sustain high-quality immunization services in African countries. Strengthening RI will in turn sustain the gains made to eradicate poliovirus in the region.

Polio supplementary immunization activities and equity in access to vaccination: evidence from the demographic and health surveys

Every year, large numbers of children are vaccinated against polio during supplementary immunization activities (SIAs). Such SIAs have contributed to the >99% decline in the incidence of poliovirus cases since the beginning of the Global Polio Eradication Initiative. It is not clear, however, how much they have also contributed to reducing poverty-related inequalities in access to oral polio vaccine (OPV). We investigated whether the gap in coverage with 3 doses of OPV between children in the poorest and wealthiest households was reduced by SIA participation. To do so, we used data from 25 demographic and health surveys (DHS) conducted in 20 countries since 2002. We found that, in several countries as well as in pooled analyses, poverty-related inequalities in 3-dose OPV coverage were significantly lower among children who had participated in SIAs over the 2 years before a DHS than among other children. SIAs are an important approach to ensuring equitable access to immunization services and possibly other health services.

Pakistan's expanded programme on immunization: an overview in the context of polio eradication and strategies for improving coverage

Since its inception in 1978, Pakistan's Expanded Programme on Immunization (EPI) has contributed significantly towards child health and survival in Pakistan. However, the WHO-estimated immunization coverage of 88% for 3 doses of Diptheria-Tetanus-Pertussis vaccine in Pakistan is likely an over-estimate. Many goals, such as polio, measles and neonatal tetanus elimination have not been met. Pakistan reported more cases of poliomyelits in 2011 than any other country globally, threatening the Global Polio Eradication Initiative. Although the number of polio cases decreased to 58 in 2012 through better organized supplementary immunization campaigns, country-wide measles outbreaks with over 15,000 cases and several hundred deaths in 2012-13 underscore sub-optimal EPI performance in delivering routine immunizations. There are striking inequities in immunization coverage between different parts of the country. Barriers to universal immunization coverage include programmatic dysfunction at lower tiers of the program, socioeconomic inequities in access to services, low population demand, poor security, and social resistance to vaccines among population sub-groups. Recent conflicts and large-scale natural disasters have severely stressed the already constrained resources of the national EPI. Immunization programs remain low priority for provincial and many district governments in the country. The recent decision to devolve the national health ministry to the provinces has had immediate adverse consequences. Mitigation strategies aimed at rapidly improving routine immunization coverage should include improving the infrastructure and management capacity for vaccine delivery at district levels and increasing the demand for vaccines at the population level. Accurate vaccine coverage estimates at district/sub-district level and local accountability of district government officials are critical to improving performance and eradicating polio in Pakistan.