Use of a Fractional Dose of Inactivated Polio Vaccine (fIPV) to Increase IPV Coverage among Children under 5 Years of Age in Somalia

"The study findings are promising in the use of fIPV in mass campaigns to realize better coverage and global polio eradication."

There have been no wild poliovirus (WPV) cases seen in Somalia since August 2014. However, in 2017, there was a surge in the number of cases of circulating vaccine-derived poliovirus type 2 (cVDPV2), even with different intervention responses using monovalent oral polio vaccine type 2 (mOPV2). This study aimed to assess the use of fractional inactivated polio vaccine (fIPV), a smaller dose of the polio vaccine, equal to 1/5 of a standard dose, as a polio vaccination delivery model, and to identify the main opportunities for and challenges to the use of fIPV in the future for vaccinations.

Between September 2021 and December 2021, federal and state ministries of health, the United Nations Children's Fund (UNICEF), and the World Health Organization (WHO) conducted 2 rounds of polio immunisation campaigns, given at an 8-week interval, using fIPV as a pilot delivery model in 5 districts: Berbera, Garowe, Dhusamareeb, Abdulaziz (in Mogadishu), and Dolow. This study focused on assessing the process and outcome of piloted campaigns and further understanding the acceptability of this vaccine among frontline healthcare workers and the community.

Prior to the campaigns, microplanning exercises were conducted in all 5 districts. For example, the key personnel required for the campaign, such as vaccinators, social mobilisers, district field assistants, supervisors, and recorders, were trained. The area teams assessed the capacity, accessibility, and visibility of the sites and the availability of a referral hospital within the district.

In contrast to oral polio vaccine (OPV) campaigns, in which house-to-house visits constitute the primary strategy for vaccination activities, the fIPV campaign was conducted at fixed sites, such as maternal and child health (MCH) centres, and through the deployment of teams to designated vaccination stations. Social mobilisation activities were undertaken by SOMNET, a social mobilisation network for immunisation in Somalia, with the support of the UNICEF social and behaviour change communication (SBCC) team, before and during the campaigns. These activities included district social mapping, refusal monitoring and conversion, district communication plans (DCPs), nomadic movement tracking, printing and distribution of key information education and communication (IEC) messages, and community orientations using sound trucks and house-to-house mobilisations. In addition, awareness of the campaign was promoted using posters and banners, radio and television, public announcements, and the engagement of religious and community leaders.

The study used 2 designs: a quasi-experimental design used to pilot fIPV in 5 districts and a cross-sectional study using both quantitative and qualitative approaches to collect primary data. A simple random sampling method was used to select 2 out of the 5 pilot districts for household surveys to study 768 participants. Key informant interviews were used to collect data from key frontline health workers and health/immunisation officials involved in the campaigns. In addition, 48 parents who had their children vaccinated with fIPV participated in 6 focus group discussions (FGDs). Secondary data from the pilot campaigns were analysed, such as administrative pilot data, lot quality assurance sampling (LQAS), and post-campaign communication assessments.

A total of 131,789 children aged 4-59 months were included in the pilot. Among these, 126,659 (96.1%) and 126,063 (95.6%) children were vaccinated in rounds 1 and 2, respectively. Of the 768 households assessed, 99.9% had their children vaccinated. Nearly half of the few children who were not vaccinated were missed due to the parent of the child not being at home (48%). In short, evidence indicates that the majority of children missed the vaccination for reasons other than refusal.

Based on the quantitative survey, 638 (83.1%) out of the survey of 768 households reported they received precampaign information, and over half of them (52.2%) gained awareness through a single information source. Among this group, the key sources of information about the campaign were social mobilisers (52.2%) and vaccinators/health workers (15%). Mass media, such as radio and TV, accounted for <5% of caregiver campaign awareness. It was noted that health education activities were mainly confined to towns and were not well visible in rural communities. 

The main reason that motivated more than half of the respondents (51.4%) was to prevent their children from getting poliovirus, whereas 23.3% heard that the new vaccine was better than the one previously used, 21.3% said they wanted their children to stay healthy, and 3.6% of the interviewees received encouragement after they had seen that their relatives and friends were bringing the children for vaccination.

A total of 250 caretakers were interviewed about their views on fractional IPV and whether they would prefer it for their children. All 250 (100%) recommended the use of fIPV in the future. Over half (60.8%) of the 250 caregivers were motivated to accept fIPV because there was no discomfort or pain experienced during injection (which uses PharmaJet, a needle-free injector). Ninety-seven percent of the qualitative study interviewees were satisfied with fIPV injection and recommended its use for routine immunisation.

In the key informant interviews, participants described their experiences with the implementation of the fIPV pilot as a fast and child-friendly delivery strategy. One respondent said, "the training given to all supervisors, vaccinators, and social mobilizers, and different methods of advocacy and social mobilizations had played an important role in the success of the pilot."

There were two major challenges that the subjects in this study mentioned: (i) the initial fear of the new technology and the fact that caregivers heard about the project being piloted, and (ii) social mobilisation messages were not adequately tailored to promote new technology (needleless injector) and fIPV but rather focused on polio vaccination. When asked, the health authority said they wanted to avoid further confusing the community, which had already shown fatigue in receiving several new vaccines regularly.

Participants recommended that social mobilisation should be conducted well before the campaign and should specifically promote the additional benefits that intradermal fIPV administered through the new technology brings into the polio vaccination programme. 

Overall, the study findings demonstrated that it was viable to plan and implement the fIPV campaign and achieve higher coverage in Somalia. There was some initial hesitancy among some mothers regarding the use of the needleless injector because "the technique and vaccine itself were new to us". However, it was later shown that the administration of the vaccine was much easier and painless than IPV injection.

As reported here, critical elements to the success of the fIPV campaign in Somalia included: strong government leadership at the national and state levels; well-coordinated technical and operational support from UNICEF, WHO, and partners; clearly defined standard operating procedures for the intervention; and the well-established experience of implementing OPV campaigns in the past.

In conclusion: "fIPV will potentially be used by policymakers in the design of polio eradication campaigns that integrate the fIPV vaccine into routine or supplementary immunization."