Immunisation services are essential for any health system to ensure protection against major transmissible diseases. Armed conflicts often influence the availability, quality, accessibility, and uptake of vaccination services, which can lead to the emergence of outbreaks and epidemics [1, 2]. The restoration of regular immunisation services in emergency contexts has not been extensively studied, and protracted crises “underscore the need to consider matters beyond the emergency mindset” [3]. Furthermore, health partnerships remain largely centred on national governments [4], raising the question of how areas beyond state control can best organise routine vaccination services.
The Syrian conflict, which started in March 2011, has had a devastating impact on the health system of the country; with vaccination coverage dropping from more than 90% for the Diphtheria, Tetanus & Pertussis (DTP) vaccine pre-conflict, to less than 10% in some areas [5, 6]. With the fall of some areas under opposition control, the Syrian government began to withhold vaccinations from these areas, while simultaneously attacking healthcare facilities and infrastructure [7]. The decline in vaccine coverage resulted in outbreaks of Vaccine Preventable Diseases (VPDs), including polio (2013, 2017) and measles (2017, 2018) [8, 9]. This led to vaccination becoming a priority for the humanitarian sector following the outbreak of wild poliovirus in October 2013.
Syria is now roughly divided into three main areas of control: the self-administration region of northeast Syria controlled by Kurdish majority forces, the governmental areas in the central, coastal and southern regions, and various opposition forces in the northwest. These delineations are visually depicted in Fig. 1, where the regions are represented by the colours yellow, red, and green, respectively [10]. Opposition controlled areas in northwest Syria has a population of about 4.5 million people, of whom over a third, 1.8 million, live in camps, which is the area of focus in this study [11]. According to The United Nations Office for the Coordination of Humanitarian Affairs (OCHA), about 90% of the population is dependent on donor aid for their subsistence, including for health care [12]. Northwest Syria is governed by two main forces, the opposition forces with Turkish support in northern Aleppo, and Hayat Tahrir Al-Sham (HTS) in Idlib Governorate [13]. HTS is listed as a terrorist organisation by the US, UN, EU and Turkey, preventing aid organisations from working with them [14]. As there is no recognised government in northwest Syria and no clear end in sight to the conflict, international aid organisations are facing a long-term problem of coordination, particularly in programmes which require stability and effective governance, such as routine immunisation. Humanitarian access to northwest Syria has been using border crossing points from Turkey under annually renewed Resolutions by the UN Security Council since July 2014 [15]. However, this crossing became limited to only one crossing point, the Bab el Hawa border in 2019, and later this crossing has expired with the failure to renew this UN Resolution after being vetoed by Russia and China. The Security Council’s failure to reauthorise the long-standing cross border humanitarian aid mechanism in July 2023, has laid bare the implications for the humanitarian situation in Syria coupled with a deepening divide on the Security Council’s engagement on the issue. There is now uncertainty about the future of the aid mechanism and other UN operations in the region [16].