Persistent Transmission of Circulating Vaccine-Derived Poliovirus - Somalia, January 2017-March 2024.

Since the launch of the Global Polio Eradication Initiative in 1988, substantial progress has been made in the interruption of wild poliovirus (WPV) transmission worldwide: global eradication of WPV types 2 and 3 were certified in 2015 and 2019, respectively, and endemic transmission of WPV type 1 continues only in Afghanistan and Pakistan. After the synchronized global withdrawal of all serotype 2 oral poliovirus vaccines (OPVs) in 2016, widespread outbreaks of circulating vaccine-derived poliovirus type 2 (cVDPV2) have occurred, which are linked to areas with low population immunity to poliovirus. Officials in Somalia have detected ongoing cVDPV2 transmission since 2017. Polio vaccination coverage and surveillance data for Somalia were reviewed to assess this persistent transmission. During January 2017-March 2024, officials in Somalia detected 39 cVDPV2 cases in 14 of 20 regions, and transmission has spread to neighboring Ethiopia and Kenya. Since January 2021, 28 supplementary immunization activities (SIAs) targeting cVDPV2 were conducted in Somalia. Some parts of the country are security-compromised and inaccessible for vaccination campaigns. Among 1,921 children with nonpolio acute flaccid paralysis, 231 (12%) had not received OPV doses through routine immunization or SIAs, 95% of whom were from the South-Central region, and 60% of whom lived in inaccessible districts. Enhancing humanitarian negotiation measures in Somalia to enable vaccination of children in security-compromised areas and strengthening campaign quality in accessible areas will help interrupt cVDPV2 transmission.

Estimating the Impact of Vaccination Campaigns on Measles Transmission in Somalia.

Somalia is a complex and fragile setting with a demonstrated potential for disruptive, high-burden measles outbreaks. In response, since 2018, Somalian authorities have partnered with UNICEF and the WHO to implement measles vaccination campaigns across the country. In this paper, we create a Somalia-specific model of measles transmission based on a comprehensive epidemiological dataset including case-based surveillance, vaccine registries, and serological surveys. We use this model to assess the impact of these campaign interventions on Somalian's measles susceptibility, showing, for example, that across the roughly 10 million doses delivered, 1 of every 5 immunized a susceptible child. Finally, we use the model to explore a counter-factual epidemiology without the 2019-2020 campaigns, and we estimate that those interventions prevented over 10,000 deaths.

Progress and experiences of implementing an integrated disease surveillance and response system in Somalia; 2016-2023.

Introduction: In 2021, a regional strategy for integrated disease surveillance was adopted by member states of the World Health Organization Eastern Mediterranean Region. But before then, member states including Somalia had made progress in integration of their disease surveillance systems. We report on the progress and experiences of implementing an integrated disease surveillance and response system in Somalia between 2016 and 2023. Methods: We reviewed 20 operational documents and identified key integrated disease surveillance and response system (IDSRS) actions/processes implemented between 2016 and 2023. We verified these through an anonymized online survey. The survey respondents also assessed Somalia's IDSRS implementation progress using a standard IDS monitoring framework Finally, we interviewed 8 key informants to explore factors to which the current IDSRS implementation progress is attributed. Results: Between 2016 and 2023, 7 key IDSRS actions/processes were implemented including: establishment of high-level commitment; development of a 3-year operational plan; development of a coordination mechanism; configuring the District Health Information Software to support implementation among others. IDSRS implementation progress ranged from 15% for financing to 78% for tools. Reasons for the progress were summarized under 6 thematic areas; understanding frustrations with the current surveillance system; the opportunity occasioned by COVID-19; mainstreaming IDSRS in strategic documents; establishment of an oversight mechanism; staggering implementation of key activities over a reasonable length of time and being flexible about pre-determined timelines. Discussion: From 2016 to 2023, Somalia registered significant progress towards implementation of IDSRS. The 15 years of EWARN implementation in Somalia (since 2008) provided a strong foundation for IDSRS implementation. If implemented comprehensively, IDSRS will accelerate country progress toward establishment of IHR core capacities. Sustainable funding is the major challenge towards IDSRS implementation in Somalia. Government and its partners need to exploit feasible options for sustainable investment in integrated disease surveillance and response.