Symptoms typically include fever, cough, runny nose, head and body aches and fatigue. Some people also have vomiting and diarrhea, and some develop pneumonia or other severe complications.
Older people also recover more slowly.
"Once a crisis like a flu-like illness hits, they run out of their energy quickly, which makes them weak and appear to be sicker than other people," Nazir said.
Some residents of long-term care facilities can also be reluctant to get the vaccine, Nazir said. But it could be the difference between life and death. Vaccines are about 65 percent effective at preventing the flu, and they also lessen the severity of symptoms for those who still end up getting sick.