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

Introduction

Immunization is one of the most cost-effective public health interventions and constitutes a cornerstone strategy among numerous global health programs aimed at improving population health. ¹ The 2 strategies for the delivery of this landmark intervention are a routine expanded program on immunization (RI) for eligible individuals and episodic supplementary immunization activities (SIAs). RI services are generally health facility-based and conducted year-round. SIAs are additional opportunities to provide supplemental vaccine dose(s) to an eligible population. ² SIAs are often delivered within and outside of the health facilities. SIAs provides the means to reach individuals or populations that might have been chronically missed or underserved. Also, SIAs are aimed at reaching large numbers of a target group within a short period; otherwise termed as campaign or mass vaccination.^2-4 RI could be intensified during SIAs, especially in countries that are endemic to certain vaccine-preventable diseases. ³

The United Nations Sustainable Development Goals (SDGs) 3 is aimed at ensuring healthy lives and promoting the well-being of all people everywhere in the world. Vaccine-preventable diseases (VPDs) kill 2 to 3 million people annually all over the world. Consequently, numerous governments and partner agencies have been seeking to find better ways of improving the quality and expanding the vaccination delivery strategies.^5,6 One of the ways of expanding access to vaccination is by leveraging on SIAs, especially in polio-endemic countries where several rounds of SIAs or outbreak responses are held. The SIAs permits rapid access and concurrent administration of vaccine of interest and RI services. However, enormous resources are expended during the implementation of such SIAs with or without embedded RI services. SIAs and RI often employ the same pool of limited financial, human, and material resources. Hence, there is a need to objectively assess the influence of SIAs on RI indices toward achieving optimal outputs and outcomes. Available pieces of evidence regarding the effectiveness of this approach have yielded mixed results. Some studies showed SIAs’ supportive (strengthening) effect on RI while others showed contrary findings (ie, weakening effect on RI).^7-11

In light of the above, this study would provide a better understanding of the relationships between SIAs and RI, and provide immunization program managers and decision makers more robust evidence that will inform planning, resource mobilization, project implementation, and supportive supervision. Consequently, we assessed the contribution of SIAs on access and utilization of RI services in Kebbi State, northwestern Nigeria.

Methods

Results

Contribution of SIAs on RI

There were rounds of oral polio SIAs in January and April, fIPV campaign in August, and MNTE campaign in September 2019. RI services were integrated with the SIAs in all the campaigns except the MNTE campaign, and their contributions are presented in Table 1. For all the selected vaccines, the highest contributions (65% to 74% depending on the vaccine) were observed during August 2019 fIPV campaign. During the August 2019 campaign, at least two-thirds of the children vaccinated for all RI vaccines were reached during the campaign. On the other hand, the least contribution was noted during January SIAs.

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Table 1.

Contribution of SIAs on RI for Selected Vaccine Types in 10 LGAs of Kebbi State, Northwest Nigeria, 2019.

Type of RI vaccine	Months of implementation
	January		April		August
	Number of children vaccinated	SIA contribution in %	Number of children vaccinated	SIA contribution in %	Number of children vaccinated	SIA contribution in %
BCG	11 163	30	9498	38	15 603	74
Penta 1	11 619	32	10 920	37	18 194	71
Penta 3	11 109	29	10 332	33	17 104	66
Measles	10 869	32	9141	42	14 203	65

Abbreviations: RI, routine immunization; SIA, supplementary immunization activities; BCG, Bacille Calmette Guerin; Penta, pentavalent vaccine.

Trend of RI Coverage for Selected Vaccines

Most of the monthly coverage of BCG, Penta 1, Penta 3, and measles vaccines were above 100% throughout the study period.

The lowest BCG coverage was shown in February with the coverage of 85%. Then, it gradually increased from March (98%) to July (138%) and peaked in August (202%). There was a steep decline in September to 113% (Figure 1).

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Figure 1.

Nine months’ trend of BCG (Bacille Calmette Guerin) vaccine coverage in 10 local government areas (LGAs) of Kebbi State, Northwest Nigeria, 2019.

As shown in Figure 2, both Penta 1 and Penta 3 vaccines had similar patterns during the study period. The coverage for Penta 1 and Penta 3 was 100% and 95% (lowest), respectively, in February. From March, the trends of both vaccines increased to their peak in August (Penta 1 was 237% and Penta 3 was 220%). The precipitous rise in August was followed by a similar pattern of decline in coverage (ie, Penta 1 and Penta 3 dropped to 121% and 117%, respectively) in September.

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Figure 2.

Nine months’ trend of Penta 1 and Penta 3 vaccine coverage in 10 local government areas (LGAs) of Kebbi State, Northwest Nigeria, 2019.

The Penta DOR pattern showed the lowest in February with a value of 0% and the highest DOR in June with 12% (Figure 3). Except for May and June, the Penta DOR for all other months were below 10%.

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Figure 3.

Nine months’ trend of drop-out for Penta 1 and Penta 3 vaccine coverage in 10 local government areas (LGAs) of Kebbi State, Northwest Nigeria, 2019.

The lowest measles coverage reported was in February (91%). Like other vaccines, measles coverage showed an increasing trend from March (102%) with a steep rise from 129% in July to 185% in August (Figure 4).

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Figure 4.

Nine months’ trend of measles vaccine coverage in 10 local government areas (LGAs) of Kebbi State, Northwest Nigeria, 2019.

Discussion

Our study found that the integration of RI services into the 4 rounds of SIAs conducted from January to September 2019 made varying contributions to the RI coverage of the 10 LGAs studied. Notably, the greatest contribution to BCG, Penta 1, Penta 3, and Measles coverage was observed during the August 2019 fIPV campaign, where “instant noodles” were used as an “add-on” while the least contribution was during the January 2019 SIAs. Our study also revealed the highest DOR in June. Furthermore, the pull of human resources (RI service providers) from routine vaccination posts at health facilities into the MNTE campaign without concomitant administration of routine immunization vaccines during the campaign could explain the observed drop in coverage in September for all the RI vaccines reviewed in all the LGAs studied.

The observed increment in vaccination coverage for all the RI vaccines is similar to findings in a study from Madagascar, which showed that the months SIAs were implemented were the period when the largest number of measles doses were administered. ¹⁴ This RI-strengthening approach using SIAs is in tandem with the GPEI Polio End Game Strategy, which strives to strengthen RI systems through various innovations and strategies, including SIAs.^4,15 Therefore, SIAs serves as a conduit for reaching communities that were previously missed or poorly covered by RI. Our study further demonstrated how SIA could be used to deliver optimized RI service by using the community-based delivery method (outside clinic setting), intensifying community mobilization, and the use of attractive incentives.

Another important finding was that the trend of RI coverage of all the vaccines over 9 months (from January to September 2019) in the 10 LGAs was mostly above 100%. The exceedingly high coverage could be attributed to the intensified in-between-round (IBR) activities conducted in Kebbi State to boost RI coverage in addition to the routine (ie, fixed, outreach, and mobile) RI delivery strategies. WHO provided technical and logistic support to the state to implement busy market vaccinations and the quick-win interventions. The quick-win interventions were targeted vaccinations in underserved communities (such as hard-to-reach settlements, international and interstate border settlements, and nomadic settlements), areas with low immunization uptake, and densely populated communities. These interventions provided an excellent opportunity for children who have been deprived of life-saving vaccines due to the problem of geographical access, economic barrier, frequent mobility due to trade and culture, as seen among families of nomadic herdsmen and fishermen. Other areas targeted by the IBR were the major entry and exit points in Kebbi State, such as motor parks, transit areas, and checkpoints. Among other benefits, the IBR activities addressed the risk associated with the influx of persons with children whose immunization status were unknown. ¹⁶

Similarly, the study in Madagascar also found that monthly RI coverage regularly exceeded 100%, which they attributed to inaccurate estimation of the target population. ¹⁴ Inaccurate estimation of the target population as a denominator in Kebbi State could also contribute to the explanations for the consistently high monthly RI coverage rates above 100% since the estimate used (i.e., denominator) was derived from the stale 2006 National Population Census figure. The denominator used for the Expanded Programme on Immunization (EPI) might be an underestimate, given the chance of error, fluidity in population and differences in population growth across states in Nigeria. A study conducted in Kaduna State, northwestern Nigeria showed that the projected census population that was used to compute RI denominator was fraught with errors and a gross underestimate of the target population (denominator) for RI when compared with a carefully conducted mini-census (ie, microplanning and walk-through). ¹⁷

Nevertheless, a scrutiny of the RI coverage trend for BCG, Penta 1, Penta 3, and measles from January to September 2019, depicted a bit of an undulating pattern. There was a modest increase in coverage during the months when SIAs rounds were integrated with routine immunization. However, there was a steep decline in RI coverage in September when an MNTE campaign was implemented as a stand-alone, that is, without integration with the full complement of routine immunization services. One likely reason for this finding is the recruitment of RI providers as personnel for the SIAs at the detriment of RI service provision. Health care workers who routinely offer RI services were engaged as vaccinators during SIAs, particularly the MNTE campaign (without the routine delivery of RI services at health facilities during the period). A study conducted in South Africa concluded that SIAs might have a negative impact on the health systems by diverting resources from other activities, including RI and disrupting the regular functioning of service provision. ¹⁸ In the South African study, they assessed the impact of SIAs on some maternal and child health indicators, and it showed that there was a significant decrease in the total number of immunized children before 12 months of age. ¹⁸ Also, the study in Malaysia corroborated this finding as the monthly average number of doses of Measles vaccine administered through RI was significantly lower in the months following each SIA suggesting a potential disruption of RI by SIAs. ¹⁴ In a qualitative study of 6 countries, EPI staff reported being overloaded with additional work during SIAs; there was a shortage of RI vaccines during SIAs in Vietnam; and additional remuneration during SIAs in Cameroon and Ethiopia was enough to motivate EPI staff to be more committed to SIA responsibilities. These reasons explained why health services, including RI, were interrupted during SIAs. ¹⁹

Another important finding was the Penta DOR, which showed a gradual rise from 4% in January 2019, peaked in June 2019 (12%), but suddenly decreased to 3% in July 2019 and rose to 7% in August. The pattern observed in the Penta DOR from May to August could be explained by the fact that more children who had hitherto been missed or left out were reached and initiated through intensified RI activities, such as IBR, and RI services integrated with SIAs. The IBR intervention started in May and ended in July, thus explaining the gradual rise observed in DOR to 10% in May. The decrease to 3% and 7% in July and August 2019 respectively, could be the result of mop-up of previously unimmunized children that had been initiated into RI, thus resulting in a fewer cohort of unimmunized or dropout children within the communities. In fact, despite the pulling effect of August fIPV (that was strengthened by strong community mobilization, the provision of attractive add-ons, and the community-based delivery), there was no massive increase in the drop-out from the end of IBR activities in July, and to August. Furthermore, the figures in Table 1 supported the above explanation, which showed that the children vaccinated with Penta 1 vaccine during the fIPV campaign were 71% compared with 66% for Penta 3 for the target population in August 2019 in the 10 LGAs. During the August 2019 fIPV campaign, instant noodles (a form of pasta) was given to the children as an incentive after the administration of the RI antigens. The noodles acted as an attraction and might have attracted more eligible children, especially missed opportunities and left-outs, through their caregivers to the vaccination posts. Another possible reason for the patterns of Penta DOR observed might be due to the use of house-to-house community mobilizers who line-listed and mobilized eligible children during the pre- and intracampaign period, thereby improving the demand for the vaccines. The WHO recommends that the DOR should not be more than 10%. ²⁰ In light of the above, SIAs integrated with RI can potentially address both coverage and drop-out issues, if they are of good quality and done over short and regular intervals within the year. However, the reliance on SIAs may negatively affect the sustainability of RI services in terms of cost and resilience of PHC services in delivering composite basic health services to the communities, especially the vulnerable and underserved populations.

Our study was not devoid of limitations. First, it was a descriptive study. Hence, we did not eliminate the influence of potential confounders, such as intensified RI activities and in-between Round Activities. Second, we analyzed and interpreted limited variables, because the data used for this study was hitherto collected for routine Polio Eradication Initiative/EPI programming and not intended for operational research. However, we were able to optimize the variables available to address the objectives of our study. However, despite these limitations, our article provides a further justification to strengthen the integration of SIAs with the full complement of routine immunization services. We further showed the relevance of intensifying community mobilization, community-based approach, and use of attractive commodities to stimulate vaccination uptake at especially in settings where there is low immunization coverage amid social deprivation.

In conclusion, our study demonstrated that the integration of RI into SIAs could improve RI coverage, especially if it is community-based and fortified with strong community mobilization and provision of attractive commodities (ie, add-ons). The integration of RI service provision during SIAs was commendable because it offered unimmunized children and defaulters from RI services (fixed or outreach sessions) an opportunity to be reached and get immunized. Although SIAs were instrumental at increasing RI coverage and could potentially reduce the drop-out rate, the disruption of RI services might occur due to overlapping resources and poor planning. Therefore, SIAs should be adequately planned by program managers to strengthen RI programs via integration during the implementation of SIAs. Even though the resources for RI services and SIAs could be pooled together, proper mobilization, allocation, and distribution of human and material resources would be needed to prevent adverse outcomes.