The Clover Health Flu Shot Monitor also found 35% of seniors survived did not get a flu shot last year. Among those declining the shot, 43% said they were concerned it would make them sick and 35% said they didn’t think the shot would be effective.

Among seniors over age 80, the percentage planning to get the flu shot jumped to 75%, while 60% of those between ages 60 and 69 said they would get the shot.

“Not only are these older adults putting themselves at risk, but also their friends and family members,” said Kumar Dharmarajan, M.D. and Chief Scientific Officer at Clover Health. “It’s concerning to see that so many people in this at-risk demographic do not intend to get vaccinated.”

Even months after recovering from the flu, older adults remain at increased risk for a heart attack, stroke or disability due to weakened immune systems and slower recovery times.

The Clover Health Flu Shot Monitor was conducted by Wakefield Research on 1,000 adults ages 60 and older throughout the U.S. The survey was administered September 18-28.