A Practice Note discussing the US federal antitrust agencies' actions and guidance in response to the 2019 Novel Coronavirus Disease (COVID-19). This Note discusses COVID-19's impact on the antitrust agencies' merger and enforcement activities, such as their acceptance of electronic Hart-Scott-Rodino (HSR) filings and modifications to statutory or agreed-on timing of investigations or litigations, and guidance that they have issued relating to competitor collaborations.