The coronavirus outbreak couldn’t have come at worst time for the 2020 census, and, to wit, the Census Bureau announced Wednesday that it was pausing field operations through April 1 to protect its workers and the public in the pandemic.

Americans can still respond to the survey online, over the phone or by mail. But the Bureau relies on in-person interactions to encourage participation, follow up with households that haven’t responded on their own and conduct other operations aimed at obtaining information for the survey.

Much of that activity isn’t in full swing yet, and the Bureau said on Wednesday that it “will continue to evaluate all 2020 Census operations” throughout the current suspension.

This guidance that the Bureau provided fieldworkers on avoiding COVID-19 (before their operations were put on pause) helps illuminate why this outbreak is creating such a challenge for the decennial census.