West Nile virus in Europe: after action reviews of preparedness and response to the 2018 transmission season in Italy, Slovenia, Serbia and Greece

We designed an AAR study to enable the participatory involvement of all the stakeholders potentially involved in a WNV outbreak response (including the human health, animal health, medical entomology/vector control and the blood/transplant safety sectors), targeted to a European context (i.e. with reference to existing relevant EU/EEA and European regulatory frameworks) and with a focus on public health preparedness and response from a One Health perspective and on communication and collaboration mechanisms. We designed the protocol to perform an AAR specifically on the 2018 WNV outbreak event, considering as primary methodological references recent European Centre for Disease Prevention and Control (ECDC) [13] and World Health Organization (WHO) [14] guidance documents.

We adopted a mixed method approach, combining traditional AAR techniques (interviews, working groups), with formalized methodologies from management and organizational studies (e.g. process analysis). Namely we used two methodological references: (i) participatory design techniques to enable the active participation of all the actors involved in the national WNV 2018 outbreak event into the common workshops established by the protocol [15‐17]; and (ii) process design and analysis (specifically adopting Business Process Modelling Notation (BPMN) [18]) to identify, model and analyse the communication flows and the coordination needs among the different involved actors, and to map complex surveillance and response pathways [19, 20].

The AAR was implemented according to pre-defined study steps (Fig. 1) and site visits were planned according to a standard 4-day format (Fig. 2). The methodology was successfully assessed against the ECDC 11-item tool for AAR methodological rigour [16].

We structured the AAR in three different phases (see Table 1): (i) Participants identification; (ii) Data collection & site visits; (iii AAR Quality Check & Feedback.

An AAR on the 2018 WNV transmission season in Europe was successfully implemented in three very different country contexts (i.e. Slovenia, Italy and Serbia) without requiring any adjustment in the content, structure or tools in the protocol. The structure of the protocol proved flexible enough to enable a fourth study in Greece using simplified retrospective mapping with comprehensive results. In all countries, the AAR successfully brought stakeholders together to discuss the public health response to the WNV 2018 outbreak event. The opening participatory workshop involved all participating institutions and created a solid and shared foundation for the in-depth interviews of the following days. It helped to address collective knowledge gaps, align perspectives across sectors, and in some cases even to identify immediate measures that could be undertaken to improve the response to the 2019 transmission season. Organisational system mapping, where performed, highlighted clearly defined communication flows in the different WNV preparedness and response systems. We consistently highlighted high levels of information exchange between sectors and a strong effort to produce easy to access and to read near real-time inter-sectorial information related to the WNV surveillance and response activities. These points are in line with the coordination needs of a complex and diversified network of different organizations, which intensify their collaboration for specific events and have to establish a mutual cooperative behaviour [22‐24].

The four countries described in this study have very diverse experiences in relation to WNV (endemic countries with hundreds of human cases vs newly affected countries with few human cases reported in 2018) and, also, very diverse in terms of geographical extension, population size and public health system organization. All four countries had preparedness plans and multi-sectorial surveillance and response systems in place prior to the 2018 outbreak and shared similar strengths, mainly linked to cross-sectoral coordination between actors. This suggests that the investment in preparedness to face the WNV 2018 outbreak event was recognized, on hindsight, as an asset. Conversely, the problems identified were more context specific. Nonetheless, both recurring strengths as well as recurring specific problems were identified. As concerns the latter (recall Table 8), these are very frequently matters that could be addressed at the national and sub-national level if appropriate levels of strategic attention can be harnessed, which is inherently challenging. Activities that can facilitate this include assessing the added-value of critical activities, such as sustained mosquito surveillance programs, in order to ensure appropriate funding. Planning for specific activities, such as media training and operational arrangements to reduce strain on front-line public health workforce during outbreaks, can help to alleviate the strain caused by increased media attention during crises. On the other side, administrative arrangements to streamline or at least pre-consider procurement of biocides and other relevant materials required during outbreaks of WNV, often involve a multiplicity of actors and administrative levels. In some instances, countries may first need to weigh the efficacy of various biocides with their environmental impacts. If this aspect can be prioritized in the aftermath of the 2018 outbreak, it would call for a long-term planning and preparedness process that should preferably take place during “peace-time”. Finally, the scientific community may embark upon research to address the key “known unknowns” surrounding WNV, which have included the role of certain bird species in WNV transmission and ecology; the impact of vector control on human transmission; and the development of resistance to insecticides. As these issues are relevant for all countries that experience WNV transmission, international research projects might be a feasible path forward.

Meanwhile, it will be important to pay adequate attention to the identified recurring strengths (Table 7) to ensure that these are safeguarded and built upon. Many of the strengths relate to inters-sectoral frameworks that enable a One Health approach to WNV. Mechanisms that continue to foster trust and collaboration between relevant agencies and that enable the prompt an efficient exchange of relevant information, including surveillance data, are likely to remain of particular importance. Finally, efforts should be allocated to ensure that laboratory systems continue to adequately diagnose WNV infection across humans, birds, mosquitos and horses.

The preparedness mechanism of the four European countries that implemented the AAR proved to be strong enough to sustain the impact of the extraordinary 2018 transmission season. The WNV AAR met the objectives defined by both ECDC and WHO for this type of study and was recognized as an added value in implementing countries.

In the context of WNV, this study highlights the importance of a cross-sectoral and cross-disciplinary approach to strengthening preparedness to infectious disease threats. Formal inter-sectoral frameworks that support coordinated One Health surveillance and response – within and across national borders – during WNV transmission seasons, may be increasingly important in this era of climate change and intensive agriculture. Laboratory capacities to ensure timely and accurate confirmation must be safeguarded and strengthened where necessary. Risk communication, especially given the rapid pace of change in social media, requires sustained investment and training across public health domains. Finally, where common knowledge gaps remain, such as on the longer-term “known unknowns” identified in this study, there is value in pursuing multi-country research partnerships, sponsored by regional and/or international bodies.