Abstract: A wearable cardioverter defibrillator (“WCD”) system includes a support structure that can be worn by a patient, and a defibrillator coupled to the support structure. An ECG input, rendered from an ECG of the patient, may meet a primary shock criterion. One or more sensor modules are further provided, which are worn by the patient at different times. The sensor modules may monitor different physiological parameters of the patient, and transmit signals about them. The WCD system further has a multi-sensor interface to receive the transmitted signals, and a processor to determine from them whether a secondary shock criterion is met. If both the primary and the secondary shock criteria are met, the decision is to shock. The signals increase specificity of the detection, while the patient can wear different modules depending on context.