We sought to address the prior limitations of symptom checker accuracy by analysing the diagnostic and triage feasibility of online symptom checkers using a consecutive series of real-life emergency department (ED) patient encounters, and addressing a complex patient population – those with hepatitis C or HIV. We aimed to study the diagnostic and triage accuracy of these symptom checkers in relation to an emergency room physician-determined diagnosis. An ED retrospective analysis was performed on 8363 consecutive adult patients. Eligible patients included: 90 HIV, 67 hepatitis C, 11 both HIV and hepatitis C. Five online symptom checkers were utilised for diagnosis (Mayo Clinic, WebMD, Symptomate, Symcat, Isabel), three with triage capabilities. Symptom checker output was compared with ED physician-determined diagnosis data in regards to diagnostic accuracy and differential diagnosis listing, along with triage advice. All symptom checkers, whether for combined HIV and hepatitis C, HIV alone or hepatitis C alone had poor diagnostic accuracy in regards to Top1 (<20%), Top3 (<35%), Top10 (<40%), Listed at All (<45%). Significant variations existed for each individual symptom checker, as some appeared more accurate for listing the diagnosis in the top of the differential, vs. others more apt to list the diagnosis at all. In regards to ED triage data, a significantly higher percentage of hepatitis C patients (59.7%; 40/67) were found to have an initial diagnosis with emergent criteria than HIV patients (35.6%; 32/90). Symptom checker diagnostic capabilities are quite inferior to physician diagnostic capabilities. Complex patients such as those with HIV or hepatitis C may carry a more specific differential diagnosis, warranting symptom checkers to have diagnostic algorithms accounting for such complexity. Symptom checkers carry the potential for real-time epidemiologic monitoring of patient symptoms, as symptom entries and subsequent symptom checker diagnosis could allow health officials a means to track illnesses in specific patient populations and geographic regions. In order to do this, accurate and reliable symptom checkers are warranted.

Tremendous advancements in syndromic surveillance strategies over the last two decades, and specifically from prior mass gatherings, have been incorporated into day-to-day healthcare analysis worldwide and have left a lasting indirect impact since their inception. Mass gatherings are a daily occurrence worldwide and provide a scenario ripe for public health aims and objectives utilising syndromic surveillance. Europe is less than a decade away from hosting a colossal worldwide gathering (2024 Summer Olympics) in likely a time when the global agreement is in flux. A call to arms is needed for additional surveillance strategies incorporating mobile application symptom checker data, telemedicine, social media and social data sensing. There remains a need for an optimal combination of real-time data sensing that captures the whole population, but to reach that goal we must incorporate new advancements into baseline epidemiologic data monitoring, otherwise we will be tracking real-time mass gathering events on top of inaccurate baseline epidemiologic data.