And elders have been particularly slow to take advantage of the shingles vaccine. The Food and Drug Administration approved it a decade ago, and the C.D.C. recommends it for those over 60, including those who’ve already had shingles.

Coverage has climbed steadily, but in 2014 it had still reached only 31 percent of those over 65. As with nearly all of these vaccines, older whites were more likely to have been vaccinated than blacks, Hispanics or Asians.

Why these missed opportunities?

“Vaccines are less likely to be routinely incorporated in adult medical practice,” Dr. Bridges said. “Every time a child comes in, a pediatrician makes sure they’re up-to-date.”

Older adults often have medical issues that take precedence during brief office visits. They also see specialists who are more focused on cardiology or oncology than on flu and shingles.

Seniors and their caregivers should request vaccinations; the C.D.C. publishes guidelines and a quiz that explain which ones are recommended. Zostavax, the current shingles vaccine, reduces the risk of the disease in adults over 60 by half, and the incidence of postherpetic neuralgia by two-thirds.

(Quick primer: Shingles results from the same virus that causes chickenpox, which nearly all older Americans have had. The virus typically remains dormant for decades, but the odds of its reactivation rise steeply after 50 as the immune system weakens. The lifetime risk of shingles is one in three, rising to one in two for those over 85.)

The vaccine’s underuse can be blamed, in part, on supply shortages in its early years until about 2012. The manufacturer, Merck, and the C.D.C. didn’t increase media campaigns until vaccine supplies were sufficient; such campaigns had just started when Ms. Abate became ill. It’s not surprising that she was only vaguely aware of Zostavax.