The vaccine is becoming more accessible, but states have faced a supply shortage.
Los Angeles temporarily shut down five mass vaccination sites because they have run out of Moderna first doses.
A California doctor says this pattern will likely continue.
"Until we can get a dependable, reliable supply of vaccine coming to not just the states, but to the different regions within the states so that we can do proper planning," said Dr. John Swartzberg "We're just going to still stumble like this."
The sites won't get more doses until Tuesday or Wednesday at the earliest.
Smaller mobile locations will continue their work.