At the height of last summer, New York Federal Reserve PresidentJohn Williams temporarily roiled markets when he argued thatcentral banks running low interest rates should act boldly toinoculate their economies against unfolding ailments.

"When you only have so much stimulus at your disposal, it paysto act quickly to lower rates at the first sign of economicdistress," he said in a speech that the NewYork Fed later clarified was not meant to be a policy signal. Youwant to "vaccinate against further ills."

As Williams and his colleagues prepare for a monetary policymeeting next week, the mounting economic impact of the coronavirusis turning his academic theorizing into a practical considerationfor policy: Should the Fed cut interest rates to zero? And, if so,how soon should it act?