Emerging epidemics pose a profound challenge to public health and medical infrastructures due to their potential to induce widespread morbidity, mortality, and healthcare resource strain. Epidemic Volatility Index (EVI) is considered a simple, straightforward, easily applied, warning method that was developed to identify upcoming waves in an epidemic [1]. The method is based on the volatility of newly reported cases per unit of time and issues an early warning when the volatility change rate exceeds a threshold. Originally EVI was developed for the data on the daily confirmed cases of the coronavirus COVID-19 pandemic, caused by coronavirus-2 (SARS-CoV 2) [2]. EVI’s application to data from the current COVID-19 pandemic revealed a consistent and stable performance in terms of detecting new waves. It is highlighted that the application of early warning tools, like EVI, to other epidemics and syndromic surveillance tasks will alleviate the epidemics-associated effects via (i) containment of outbreaks, (ii) timely application of intervention strategy and (iii) resource allocation [1].
The potential benefits of such early warning tools extend beyond specific disease containment. Early warning tools in syndromic surveillance tasks come helpful for cases when a definite diagnosis/identification of the aetiological agent does not exist, but an increase in the reported cases of “general - non-specific” symptoms (e.g., respiratory infections etc.) is observed [3, 4]. Key example with immense value for public health is the monitoring of respiratory infections. Firstly, many respiratory infections are highly transmissible, meaning they can spread rapidly among populations. By monitoring the prevalence of these infections, physicians and public health officials can detect unusual patterns or upticks in cases that might signal the beginning of an epidemic. Early epidemic detection provides more time to (i) mobilize resources, (ii) implement containment measures, and (iii) inform the public to mitigate its spread [5]. Secondly, many serious epidemics and pandemics in history, such as the Spanish Flu [6], SARS [7], and COVID-19 [8], began as respiratory infections. These illnesses have shown their capacity to cause significant morbidity and mortality on a global scale. Therefore, keeping a vigilant eye on respiratory infections can help identify the emergence of a novel, potentially dangerous pathogen before it becomes widespread [9]. Lastly, early warning allows for rapid development and distribution of relevant vaccines or treatments [10]. Scientists can start researching the pathogen sooner, and healthcare infrastructure can prepare for increased demand. It also affords government agencies and health organizations the opportunity to educate the public about the situation, possible prevention measures, and symptoms to watch for, which is crucial in managing public fear and anxiety during health crises. In essence, the value of monitoring respiratory infections as an early warning system lies in enabling a proactive rather than reactive approach to disease management, potentially saving lives and resources [11].
Many European countries, including Greece, in the last years have been affected by the financial crisis that resulted in structural challenges with declines in the number of the healthcare workforce, merging of healthcare units [12]. Thus, an outbreak will push the capabilities of the healthcare system to its limits and may compromise the health of the people. Strategy and measure implementation for mitigation of the pandemic depends on the condition of the health care system and its ability to respond to an influx of COVID-19 cases. As a respiratory disease, severely affected COVID-19 patients require intensive case and use of ventilators. Furthermore, an epidemic has serious societal and economic consequences, thus initiatives from the government are needed to stimulate the affected sectors [13].
To this end, implementation of simple, easily applied, warning methods can assist experts to decide if the case augmentation is expected or not, to take further actions or not, until it is clarified what is happening. These methods as part of the syndromic surveillance scheme will aim to (i) identify illness early, before diagnoses are confirmed and reported to public health agencies, (ii) to mobilize a rapid response. Both after the global influenza pandemic in 2009 [14] and the COVID-19 outbreak in 2020 [15] the importance of reporting, monitoring, analyzing “general” symptoms/cases, disease indicators (e.g., flu-like symptoms, respiratory infections, diarrhea etc.) emerged. This is evident from the literature where many studies highlight the significance of using real-time, often non-specific symptoms or preliminary diagnosis information collected during routine healthcare provision to supplement public health surveillance programmes [3].
This study describes a pilot application of EVI to data from the pulmonary clinic of university hospital of Thessaly, Greece as an early warning tool for respiratory infections, COVID-19 and flu cases between October 2021 and June 2023. This study investigates EVI's efficacy in a clinical context and introduces an implementation of the tool in an application that facilitates automatic update of the tool and available daily output/predictions to the final user.