Articles, Blog

How Long Are You Contagious With The Flu?

November 12, 2019

Don’t worry. I’m not contagious. I’m Maddie Sofia. And what Adam just said is nonsense. Hey! You’re contagious for a lot longer than you might think. To find out why, we have to go back to when Adam first got the flu. Most of the time, the flu is transmitted from person to person through virus-containing particles. Yep, that’ll do it. Twenty-four hours later, the virus has started to take over. It hijacks Adam’s cells and starts multiplying, building up an army. Adam feels fine, but he’s already contagious. By now, Adam’s immune response has caught on to the foreign invaders and started a counterattack. And that’s actually what gives you your symptoms. Adam’s fever is actually helping him out. At high temperatures, the flu virus actually doesn’t grow that well, and some immune cells work even better. By Sunday, Adam’s feeling like garbage. His nose fills up with snot. That mucus is good at trapping foreign invaders before they can infect other cells. At this point, Adam’s airways are pretty beat up, and he starts to cough and sneeze. That works out really well for the flu because it helps it spread to somebody else. While Adam takes the day off, warriors of his immune system seek out and destroy virus-infected cells. But Adam’s immune system can actually damage his internal organs if it goes unchecked. So — as the amount of virus drops in Adam, the immune system dials itself back. He might feel more alert. He can probably even breathe through one nostril. But, there’s still some virus lurking inside Adam when he decides to come back to work. And in 3…2….1… Tiny droplets that fly from his mouth can travel as far as 20 feet at speeds ranging from 25 to 50 mph. Sometimes, they can stay suspended for hours. And that’s bad, because some of those droplets can contain virus that could get you sick. Adam is still contagious. In fact, the CDC says you are contagious one day before you start feeling sick, and up to seven days after. You’re probably the most contagious here in the middle. If you’re a kid, elderly, or you have a weak immune system, you can be contagious for even longer. So Adam, why don’t you take another day? Actually, alcohol can suppress the immune response. Get out of my house! Hi everybody! I’m Maddie Sofia. And I’m Adam Cole. I work with science correspondent Joe Palca on a project called Joe’s Big Idea. If you want to check out videos about the scientific invention process, click here. Please subscribe to our channel. There will be lots more videos featuring Maddie in the coming months.


  • Reply Mr/Clusterfuck February 19, 2018 at 10:20 pm

    It's my 7th day after i got the flu. shouldn't have had gone to school today…oh well, now i know

  • Reply SaucerJess February 19, 2018 at 10:28 pm


  • Reply Daniel Neira February 20, 2018 at 1:10 am

    I have the flu right now :,,(

  • Reply Oli2.01 February 20, 2018 at 4:28 am

    I never think I have had the flu and just the other week I was with two persons all day that had the flu and still nothing. Is there any factors that might help me not get infected or just don't notice it? I have read being healthy help but that is definently not the case

  • Reply Adib BehrooziTV February 20, 2018 at 5:58 am


  • Reply piplupcola February 20, 2018 at 7:24 am

    Dang now I don't wanna breathe anywhere now

  • Reply Andrei Tache February 20, 2018 at 10:19 am

    Amazing video as allways!

  • Reply Diana Finkle February 20, 2018 at 2:02 pm

    Really enjoyed the video but sad the captions end early. I guess the closing is something you reuse? If so, please reuse those captions as well. Thanks! 🙂

  • Reply Maxx B February 20, 2018 at 2:48 pm

    Great video and I like Maddie, she make s a great host.

  • Reply Scott Baker February 20, 2018 at 3:31 pm

    Great video – am I the only one that noticed the guy with the boom mic in the window @ the end?

  • Reply Reading Classics February 20, 2018 at 3:50 pm

    Excellent vid. Thank you!! A quick question, too……Fact or Fiction–those who had a relative die of the flue epidemic of the 30's have a higher immune response to the flu? Asking because a relative's grandpa and gramma both died of it ( 🙁 ) and the relative NEVER gets the flu and I mean never…..they are now 83 years old!

  • Reply Amanda Christi February 20, 2018 at 5:10 pm

    Hi Maddie! Great video! Can you do one where you explain the difference between influenza and the stomach "flu"? I am so tired of explaining every year that influenza is respiratory and not gastrointestinal.

  • Reply Laura Vercammen February 20, 2018 at 5:49 pm

    Can't wait to see more videos with Dr. Maddie!!!

  • Reply Paul Marado February 20, 2018 at 6:50 pm

    Liberalism comes to the flu

  • Reply Pam H February 20, 2018 at 8:47 pm

    Is this the same for a cold? Not like I know when I have one or the other….

  • Reply Abelhawk February 20, 2018 at 8:57 pm

    And this is why I wish companies would separate vacation days and sick days.

  • Reply Hawkthehunter February 22, 2018 at 6:17 pm

    I've been coughing up mucus for 3 weeks, sorry but there is no way I could take that many sick days without being fired.

  • Reply HKO2006 February 24, 2018 at 4:47 am

    Get a mask!

  • Reply Danielle Anner February 25, 2018 at 3:34 am

    I think the addition of Maddie is fine as long as Adam and his green chair stick around. <3

  • Reply Diane Fitzpatrick February 27, 2018 at 10:39 pm

    Do I get sick pay too?? ?

  • Reply Mark Burnett February 27, 2018 at 11:11 pm The main guy at Infectious Disease control said there was a "Mis-Hap" when making the Flu shot.. Why do all news places have their head in the sand?

  • Reply Dawn Parker February 28, 2018 at 2:17 am

    I like his lunch box! Does things like elderberries really help keep you from getting sick or as sick?

  • Reply John Fredrik Hansen March 5, 2018 at 12:02 am

    I had the flu ones it was a living hell

  • Reply chachee15 April 10, 2018 at 2:24 am

    does baking soda kill this?

  • Reply Maddison McCarthy April 19, 2018 at 11:21 am

    0:20 I want that lunch box, it is glorious

  • Reply Latina K April 29, 2018 at 9:21 pm

    Got sick from someone who said they “just got over the flu”. I’m so mad. Like what are you doing out and about?? Especially when you’re not warning people…I caught it the same day too.

  • Reply igano July 6, 2018 at 6:32 am

    I wish people would stop using this kind of hipster whistle generic music. It's like watching an ad for a cellphone plan. It's a real plague. Good video otherwise, subscribed.

  • Reply William Perrow October 1, 2018 at 9:44 am

    Six months after graduating from high school I was sharing an apartment with a friend. One mid winter Friday morning I awoke with mild flu symptoms and by that night I knew I had the flu. The very next day vomiting, and fever and by evening diarrhea started. I nearly died alone in that apartment that weekend because we had no phone, my flatmate had left for the weekend and I couldn't get out of bed on my own.
    I'm 65 and healthy now and that was the last time I've had the seasonal flu because I get vaccinated every year.
    Cost = $0.00. GET IT!

  • Reply KlunkerRider October 1, 2018 at 6:39 pm

    This is why most businesses only give you 1 or 2 sick days then wonder why the entire office gets sick, stupid businesses.

  • Reply Doug F October 2, 2018 at 3:00 am

    2:36 Sound guy in reflection and microphone cord in upper left corner. I'm glad they left it in 🙂

  • Reply Anubhav Shah October 2, 2018 at 1:03 pm

    What about using purifiers/HEPA filters?

  • Reply Karin Wagner October 10, 2018 at 2:11 am

    Great video! However it assumes that people have the opportunity to stay home from work. It would be great to add that if you do have to go to work, it helps a lot if the sick person wears a mask. Mask-wearing by the sick person is much more effective in preventing the spread of germs than healthy people wearing one.

  • Reply flerida meza November 29, 2018 at 10:38 pm

    "Get out of my house!" Lol!!

  • Reply BadRonald1 December 4, 2018 at 5:33 pm

    It's like my Mom said 3 days to get it, 3 days to have it, and 3 days for it to go a way.

  • Reply JessKaRabbiT21604 February 18, 2019 at 1:53 pm

    Husband had flu. Confined to bedroom and master bath. Away from the other household members. (I have a 2 yr old and a 15 yr old) He will be coming out of quarantine on day 8 (day 9 if you count the first day he felt sick) do I need to go crazy and clean every inch of the house? This is the info I cannot find anywhere. What do we need to do once he comes back to reality to continue to protect the rest of us? Please let me know! Thank u!

  • Reply revistadearmas March 4, 2019 at 12:58 am

    The flu vaccine is BS a week later i was ill and two weeks later i got the flu again, sucks

  • Reply Sadie R July 29, 2019 at 2:48 pm

    i got the flu after going to the mall symptoms started later that night when my friend was over and she ended up leaving. next few days was a living hell i was always dizzy, coughing, and throwing up. as of today it will be my 9th day with the flu and nothing is really helping with my throwing up issue. every time i eat or take my medicine i end up throwing it up. the doctor thought i was allergic to the medicine so they gave me pills instead which worked out the first 4 days of having it, but now every time i have it i end up throwing it back up. i am being taken to the doctor’s again today to see what the problem is, honestly just think it’s because of the flu but i will update later once i get back from the appointment.

  • Reply spyralspyder November 6, 2019 at 10:28 am

    Doesn't matter. I dont have sick days.

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