In places of mass gathering, rapid infection screening prior to definite diagnosis is vital during the epidemic season of a novel influenza. In order to assess the possibility of clinical application of a newly developed non-contact infection screening system, we conducted screening for influenza patients.

The system is operated by a screening program via a linear discriminant analysis using non-contact derived variables, i.e., palmar pulse derived from a laser Doppler blood-flow meter, respiration rate determined by a 10-GHz microwave radar, and average facial temperature measured by thermography. The system was tested on 57 seasonal influenza (2008–2009) patients (35.7 °C ≤ body temperature ≤ 38.3 °C, 19–40 years) and 35 normal control subjects (35.5 °C ≤ body temperature ≤ 36.9 °C, 21–35 years) at the Japan Self-defense Forces Central Hospital.

A significant linear discriminant function (p < 0.001) was determined to distinguish the influenza group from the control group (Mahalanobis D-square = 6.5, classification error rate > 10%). The system had a positive predictive value (PPV) of 93%, which is higher than the PPV value (PPV ≤ 65.4%) reported in the recent summary of studies using only thermography performed mainly in hospitals.

The proposed system appears promising for application in accurate screening for influenza patients at places of mass gathering.