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With a record number of Americans dying of Covid-19 every day, immunizing the public against the virus is more urgent than ever. But hundreds of millions of people in the US are simply going to have to wait — probably several months — to get a vaccine.

Instead of the 300 million doses the Trump administration originally promised before the end of the year, the two vaccine developers first in line for Food and Drug Administration approval — Pfizer/BioNTech and Moderna — are expected to ship 35 million to 40 million doses total before January. Since both vaccines are supposed to be dispensed at two shots per person, that’s enough supply for no more than 20 million people.

But even reaching that many people will take some time.