“It’s a similar reason for all three in that it’s the state of your immune system to a certain extent.”
Those people also at higher risk for complications, such as pneumonia, the CDC says. Thus, a flu vaccine doesn’t just protect a recipient; it protects people to whom the recipient may otherwise pass the virus — people who often have a lot more to lose.
How it spreads
“The flu spreads through droplets that people cough or sneeze out,” Blackman said. “Those can land on surfaces and be picked up by hands and then transmitted to eyes, nose, mouth. If you touch some other area on your skin, you’re not going to get the flu.
“But if you touch your eyes or your nose, especially, it can be transmitted that way — or if someone sneezes or coughs and doesn’t cover their mouth and you are within 3 to 6 feet of them, the droplets can actually travel that far.”
This, it’s important for flu victims to cover their mouths when they cough or sneeze, Blackman said.
She said that studies have shown that the virus can survive on a hard surface as long as 48 hours and on paper or cloth as long as 12 hours. That’s why public-health workers recommend frequent hand washing as one way to improve the odds of avoiding the flu.
Once infected, a victim’s symptoms show up in one to four days, according to the CDC, and most healthy adults may be able to infect others a day before the onset of symptoms. They remain contagious for five to seven days after becoming sick, the agency says.
You cannot get the flu from a flu vaccine, Blackman said. The most commonly administered form — injectable vaccine — doesn’t even contain the virus, she said.