Highlights•A definitive diagnostic test for an infectious disease is critical for limiting disease spread, developing and deploying medical countermeasures, and mitigating social and economic harms.•The US government should facilitate contracts with testing manufacturers and laboratories before a disease emergency, so testing can be rapidly scaled up.•A permanent public-private testing coordinating body can facilitate information sharing, clinical sample access, and improved cooperation.•Early in a disease emergency, the US should swiftly establish billing codes, widespread coverage, and national payment rates for new tests.•The diagnostic testing ecosystem is part of the nation’s critical infrastructure and should receive support pre-event and during a response effort.