After a shipment of the Moderna vaccine was running behind schedule, New York City was forced to push off thousands of vaccination appointments, Mayor Bill de Blasio said Wednesday. "Our best understanding is that this was purely a shipment issue," Dr. Dave Chokshi, commissioner of the city’s public health department, explained.

The delay means that the city will have to reschedule 23,000 vaccine appointments for next week, according to the mayor. New York is now projected to undershoot its self-imposed target of 1 million vaccine doses before the end of January, mirroring a nationwide struggle in administering the vaccine.