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.

Vaccines Could Blunt U.K. Epidemic in Weeks

LONDON — Britain is on a pace to give the first shot of a two-dose coronavirus vaccine to its entire population by the end of June, if it can avoid supply and logistical issues that threaten to slow one of the world’s fastest rollouts.

The most vulnerable will get their first doses much sooner — likely over the next two weeks — which could drastically reduce deaths. People over 70, nursing home residents and workers, health and social workers, and those whose health problems make them extremely vulnerable are all on schedule to receive their first vaccine shots before Feb. 15. Together these groups have accounted for 88 percent of all Covid-19 deaths.

The timeline shows the promise of vaccination as a path out of the deadliest stage of the pandemic in the countries that are moving quickly. ...