Original:  As the crisis escalated,  was a high demand for contact tracers, and the CDC had earlier named librarians as key public health staff to support COVID-19 case investigation and contact tracing, so many librarians and library staff volunteered to help with contact tracing.
Revised:  As the crisis escalated, there was a high demand for contact tracers, and the CDC had earlier named librarians as key public health staff to support COVID-19 case investigation and contact tracing, so many librarians and library staff volunteered to help with contact tracing.
Edit intent: clarity