From the Introduction: "In a March 18, 2020, press release (CB20-RTQ.08), U.S. Census Bureau Director Steven Dillingham announced that the bureau was suspending all 2020 decennial census field operations until April 1. This action, a response to the novel coronavirus disease first observed in 2019 (COVID-19) and designated a pandemic by the World Health Organization on March 11, 2020, came at a critical time for the census. Although April 1 was the official Census Day, early data collection began in remote Toksook Bay, Alaska, on January 21. Other tightly timed field operations were underway or imminent, including the bureau's personal outreach to hard-to-count areas and groups. Dr. Dillingham stated on March 18 that if 'additional adjustments' became necessary, the bureau would make them known 'promptly.'"
CRS In Focus, IF11486
Congressional Research Service: https://crsreports.congress.gov/