The Biden administration is essentially asking vaccinated Americans to help save the unvaccinated from themselves.

The big picture: America's "pandemic of the unvaccinated" has gotten bad enough that vaccine mandates are starting to catch on, and masks are coming back — in some cases, even for the vaccinated.

• Vaccinated people's risk of serious illness is still extremely low. The problem is that there are simply too many unvaccinated Americans. That's taking a toll on the whole country, and vaccinated people will be asked to shoulder some of that burden.
• "The vaccinated are currently paying a price for the unvaccinated. #covid19 is surging again, with spillover to the vaccinated. Masks are coming back, because the honor system isn’t working," tweeted emergency physician Leana Wen.

Driving the news: Biden administration officials are debating how to expand vaccine mandates for some federal civilian health care workers as they prepare to put more testing pressure — and requirements — on the rest of the federal workforce, Axios' Jonathan Swan and Hans Nichols reported last night.

• The CDC announced yesterday that vaccinated Americans living in areas with high or substantial coronavirus transmission — about 63% of U.S. counties — should once again wear masks indoors.

Between the lines: The vast majority of coronavirus cases and hospitalizations are among unvaccinated people.

• But some vaccinated people can still contract the virus, even if they never experience symptoms, and new evidence suggests that some of those "breakthrough" cases might be more contagious than initially thought, according to the CDC.
• That's the main point of bringing back masks for vaccinated people: To reduce the risk that a person with a breakthrough infection will infect an unvaccinated person, who's still at a much higher risk of serious illness or death.
• Tuesday's mask guidance was all about reducing transmissibility, even though breakthrough infections are rare, one Biden official told Axios.
• Requiring some vaccinated people to wear masks indoors again could also get unvaccinated people to mask up, too, which would have a bigger impact.

What they're saying: "Unfortunately, vaccination rates in most U.S. communities remain far too low to minimize COVID-19 transmission, and it is impossible in public settings to know who is vaccinated and who is not," said Barbara Alexander, president of the Infectious Diseases Society of America.

Go deeper: The floodgates have opened for vaccine mandates