Faced with the daunting task of parceling out a limited supply of coronavirus vaccines, Trump administration officials came up with a seemingly simple formula last year to streamline distribution of the shots.

First, federal administrators would run an automated algorithm to divide vaccine doses nationwide, based on the size of each state’s adult population. Then each state would decide how to dole out the shots to local hospitals, nursing homes and clinics.

But rather than streamline vaccine distribution, public health experts say, the algorithm has increased the burden for many states. It requires them to come up with multiple delivery plans for their weekly quotas of Pfizer and Moderna shots, even if the different shipments are destined for the same clinics and hospitals.

What scientists know about the new variants and the Covid-19 vaccines When it comes to the new variants and the Covid-19 vaccines, some of the news is very good. But some is potentially very bad indeed. Andrew Joseph STAT

here is now real evidence that at least one coronavirus variant seems to elude some of the power of Covid-19 vaccines. What, exactly, that means for the pandemic is still being sussed out.