Health investigators across the U.S. are finding it nearly impossible to keep up with the deluge of new COVID-19 infections and carry out contact tracing efforts that were once seen as a pillar in the nation’s pandemic response. States are hiring new staff and seeking volunteers to bolster the ranks of contact tracers that have been completely overwhelmed by surging coronavirus cases. Some health departments have just a few dozen investigators to respond to thousands of cases each day. Some states trimmed their contact tracing teams when virus numbers were dropping and are now scrambling to train new investigators. Others have triaged their teams to focus on the most vulnerable, such as cases involving schools.