 The breaking of contagion chains relies on two main alternative strategies: manual reconstruction of contacts based on interviews or a digital (app-based) privacy-preserving contact tracing protocol .
<fluency>  The breaking of contagion chains relies on two main alternative strategies: manual reconstruction of contacts based on interviews or a digital (app-based) privacy-preserving contact tracing protocol .
 The breaking of contagion chains relies on two main alternative strategies: manual reconstruction of contacts based on interviews and a digital (app-based) privacy-preserving contact tracing protocol .