With coronavirus infections soaring across the nation, federal health officials on Friday urged Americans in the most forceful language yet to take steps to protect themselves — starting with consistent, proper use of masks — and pressed local governments to adopt 10 public health measures deemed necessary to contain the pandemic.

The guidance reflected deep concern at the agency that the pandemic is spiraling further out of control and that many hospitals are reaching a breaking point, potentially disrupting health care across the country.

Agency officials have issued increasingly stark warnings in the waning weeks of the Trump administration, and President-elect Joseph R. Biden Jr. has promised a new national strategy to turn back the virus. On Thursday, Mr. Biden said he would call on Americans to wear facial coverings for 100 days.