NEW YORK — Mayor Bill de Blasio said Tuesday that a full shutdown of non-essential city businesses is needed to dull the impact of a second coronavirus wave, but he’d prefer to see it begin after Christmas. The decision to shut down is ultimately up to Gov. Andrew Cuomo, but de Blasio over the past two days has emphasized the need to institute a shutdown because of stubbornly high COVID-19 transmission rates that could threaten to spread hospitals too thin. On Tuesday, de Blasio revealed COVID-19 stats that remain at unwanted levels. The number of new cases taken over a seven-day average stood…