“By the end of January, we believe we’ll be able to vaccinate all seniors. By the March and April timeframe, we believe we’ll be able to vaccinate any American who desires a vaccination,” Mango said.

In reality, that timeline has always been aspirational — probably excessively so. While Warp Speed and vaccine manufacturers and others involved in the effort have moved heaven and earth to accelerate vaccine production, at the end of the day, developing, testing, and manufacturing vaccines takes time. Vaccines are difficult to produce and there are always bumps in the road.

“While it’s unfortunate, I don’t find it surprising that the timeline is being moved back,” said Michael Osterholm, director of the University of Minnesota’s Center for Infectious Diseases Research and Policy. “Clinical trials like this routinely have unexpected occurrences that delay planned timelines. It’s just not unexpected.”

As for the idea that all Americans will have had a chance to be vaccinated by the early spring, Osterholm suggested it is going to take longer.