Speaking to reporters during a conference call on Monday, Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases, offered pointed advice to older Americans about the spread of covid-19, the disease caused by the novel coronavirus that is spreading across the country.

“This seems to be a disease that affects adults and most seriously, older adults starting at age 60,” Messonnier said. “There is an increasing risk of disease and the risk increases with age.” With that in mind, older Americans were advised to stockpile necessary medications and groceries as well as to avoid travel or crowded places. Friends and family members of older Americans were advised to make similar preparations — in case they found themselves in a position of having to care for someone in the higher-risk population.

What Messonnier didn’t point out is that the population of Americans aged 60 and older is massive and growing.

In the most recent year for which full data are available, 2018, the population of the United States was about 327 million. Of that number, about 37 million were aged 60 to 69 and 35 million aged 70 and older. In other words, about 22.2 percent of the country falls into Messonnier’s “older adults” category.

That’s up significantly since 2000, when only 16.3 percent of the country was aged 60 or older. That more than 1 in 5 Americans now fall within that age category added significance to Messonnier’s additional advice: Those who might need to care for an older American should similarly prepare to do so. It’s advice, then, that might be applied to a third of the country or more.

Among those included in Messonnier’s warning are many of the federal officials responsible for managing or responding to the outbreak.

President Trump is the second-oldest president in American history after Ronald Reagan. The Washington Post reported on Sunday that Trump’s personal doctor has been attending some White House meetings about the spread of the virus and “people with flu-like symptoms are being urged not to come into the complex.”

(Trump, George W. Bush and Bill Clinton were all born within about two months of one another in 1946.)

In the past 40 years, the density of older members of Congress has also increased. This year, nearly half of House members were aged 60 or older on Jan. 20 (the benchmark for the president ages on the chart above). More than two-thirds of senators were as well.

On Sunday, NBC News reported that members of Congress, recognizing their vulnerability, were considering recessing the legislature until the immediate threat of the virus had passed. Several members of Congress have self-quarantined after interacting with someone at a conservative conference held near Washington last month who tested positive for the virus.

In the Monday conference call, Messonnier was sympathetic to the request that older Americans prepare for the virus.

“I understand these recommendations may not be popular … and that they may be difficult for some people,” she said. “At CDC, our number one priority is the health and safety of the American people. These are the kind of recommendations that I’ve made to my parents, and I’m taking the appropriate steps recommended for family members of vulnerable people.”

Among those vulnerable people are many of Messonnier’s bosses within the administration.