Abstract Background Automated diagnostic device to measure child’s vital sign is a global unmet demand. Having separate diagnostic devices to measure multiple vital signs is more expensive, and can be complex for health workers. An automated “all-in-one” device would help avoiding extra costs as well as maintenance challenges associated with multiple devices. In addition to improve classifying childhood illness, such an automated device would also increase adherence to guidelines, optimal use of antibiotics, and a reduction of unnecessary referrals. Methods We studied an automated device in Malawi, which was designed to measure multiple key vital signs (SPO2, respiratory rate, temperature) among newborn, infant and children <5 years. The device collected photoplethysmogram (PPG) signals for SpO2 via a universal pediatric sensor, placed on child’s finger. Temperature was measured via infra-red signal from child’s forehead. Accelerometry measures respiratory rate, by placing the device around the child’s belly. The CO2 sensor data together with video recordings of child’s respiration offered the reference for child’s respiration count. Results Preliminary analyses of valid PPG signals, video annotated respiratory count and CO2 sensor data revealed the following key results: - For SPO2, the performance of the target probe among 170 subjects appears extremely well with even the smallest and largest children. - Among 145 subjects with valid CO2 data, 93 subjects were fully calm and had a regular breathing pattern. Comparing accelerometry measurements from 93 calm subjects with the reference data, the root of mean square error (RMSE) was only 1.18 respiration per minute (RPM). Excluding four outlier measurements from 145 subjects’ dataset, the RMSE for the remaining 141 subjects was 1.76 RPM. Conclusions This study results demonstrated the proof of concept that the device measures key vital signs among newborn, infants and children <5 years, using a reusable single-based probe. Key messages Automated diagnostic device measures key multiple key vital signs (SPO2, respiratory rate, temperature) among newborn, infant and children <5 years. Such an automated device may have potential to ensure accuracy in diagnosis, increasing adherence to recommended guidelines, optimizing use of antibiotics, and reducing unnecessary referrals.