In AMC's The Walking Dead, how did the flu take out so much of the population? Me and people I've known have gotten plenty of them. The only time I hear of them killing people is extremely weak and frail children or elderly people. They are also not treatable via antibiotics AFAIK. The people seemed to be able to stay warm, have a ready supply of clean food and water, possibly vitamins too.

How would so many apparently healthy adults fall to a realistic strand of flu that exists in real life?

  • Because plot...
    – ChrisH
    Commented Jul 16, 2014 at 14:29
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    1918 flu killed fast with the same symptoms. Coupled with the existing zombie virus everyone was already infected with
    – user18979
    Commented Feb 16, 2015 at 23:12
  • It could very well be a new strain. New strains of diseases pop all the time!
    – user26491
    Commented Oct 4, 2015 at 4:51
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    The Spanish flu killed 100 million people. Depends on the flu. Also, the characters are probably stressed, malnourished, and exhausted all the time and thus more susceptible to disease Commented Dec 12, 2016 at 21:25
  • Not a full answer but a relevant anecdote. I've lived in my home country for 30 years and I don't really get sick, I'm used to the usual cold/flu and shake it off well. My SO, however, is from a different continent, and is not resistant to my country's selection of cold/flu bugs. She is liable to catch something, and because she gets really sick, she becomes a breeding ground for the bug/virus, which in such a strong concentration does get me sick as well. So for TWD, if a few people become very ill, they can massively boost the spread of the bug/virus to others who wouldn't have gotten sick
    – Flater
    Commented Feb 4, 2019 at 11:37

7 Answers 7


From Wikipedia

Influenza spreads around the world in seasonal epidemics, resulting in about three to five million yearly cases of severe illness and about 250,000 to 500,000 yearly deaths,[18] rising to millions in some pandemic years. In the 20th century three influenza pandemics occurred, each caused by the appearance of a new strain of the virus in humans, and killed tens of millions of people.

So by itself, Influenza is pretty nasty. Add to that the fact that everyone is already quite unhealthy and most likely hurt in one way or another... massively compromised immune systems... and the flu would be even worse. No medication? That's adding insult to injury. Now... the detail we don't know for sure... since everyone is infected, does that compromise their immune system even more?

  • Fair enough. I guess the whole "applied phlebotinum" aspect (tvtropes.org/pmwiki/pmwiki.php/Main/AppliedPhlebotinum) could explain it away. What still gets me is why a doctor/vet would advise antibiotics for a viral infection. I'm surprised he didn't recommend antiviral meds or just stuff to remedy the symptoms.
    – Cloud
    Commented Jul 15, 2014 at 20:35
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    Any medication they could go and look for is a bonus... but he's going to send people looking for the most common medicine that would be the most "helpful". I put that in quotes, because looking for medicine that could save certain characters is more of a plot device than an exercise in logic. Audience hears antibiotic, they think medicine that is the cure. However... in random searches, you'd probably be more likely to find antibiotics.
    – Bon Gart
    Commented Jul 15, 2014 at 20:39
  • YEah, that would be useful in general. Based on the context, it seemed as if he planned to use it specifically.
    – Cloud
    Commented Jul 15, 2014 at 20:42
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    @Dogbert "What still gets me is why a doctor/vet would advise antibiotics for a viral infection." Antibiotics are taken during viral infections primarily to prevent many potential secondary infections that may be far more deadly due to the weakened state. A simple cut or nearby sneeze can introduce many dangerous microbial pathogens. Commented Jul 16, 2014 at 2:37
  • +1, go read "The Great Influenza" by John Barry if you'd like to understand how deadly the flu can be (as well as why you'd take antibiotics).
    – mxyzplk
    Commented Jun 29, 2016 at 4:00

I don't think the virus was just supposed to be a regular flu, I think it was supposed to be some form of zombie Swine Flu, and here's why:

  • The virus was zoonotic as it infected and killed Violet, the pig they were keeping, just before the first infections in the prison:

    Violet the pig

  • Zombies are also infected with the virus:

    Infected zombie

  • In 2009 (just around when season 4 was being written) there were a lot of media panic about Swine Flu.

  • Hershel didn't get sick, despite being in contact with everyone that was, which fits with this:

    Existing vaccines against seasonal flu provide no protection against swine flu, A study at the U.S. Centers for Disease Control and Prevention published in May 2009 found that children had no preexisting immunity to the new strain but that adults, particularly those over 60, had some degree of immunity

  • As Wiki states:

    Some patients experience severe respiratory symptoms. (The H5N1 virus is also able to infect cells deep in the lungs with receptor type a2-3 but cannot infect cells with receptor type a2-6 making it less contagious than H1N1/09.)

    Which makes sense as in the show people die from coughing up blood.

  • I completely did not get the reference of that same biter appearing multiple times until just now. Thanks!
    – Cloud
    Commented Jul 15, 2014 at 20:47
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    That would indeed be a nasty strain... and would fit historically with new strains being extra deadly.
    – Bon Gart
    Commented Jul 15, 2014 at 20:51
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    I agree with this entirely; the flu is a strain that is virulent enough to have surpassed the groups collective immune system, and has incubated in the pigs. The environment the survivors created for themselves in the prison was tantamount to a Petri-dish. Commented Jul 15, 2014 at 22:47
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    "Zombies are also infected with the virus" .... isn't it possible / more likely that the zombie shown is not infected but WAS infected when it was alive, and the blood simply remained there through the process of becoming a zombie? I feel if zombies could "get" it, then many more zombies would have it. Commented Jul 16, 2014 at 10:51
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    @TheOneWhoPrograms There were loads of Zombies with it, in 4x04-Indifference when they're out looking for meds Bob says "They're infected, same as at the prison" Commented Jul 16, 2014 at 15:24

Severe Leptospirosis - can be life-threatening. There is a risk of organ failure and internal hemorrhaging. This occurs when the bacterium infects the kidneys, liver and other major organs. Experts are not sure why some patients develop the severe form - people who are already very ill, such as those with pneumonia, young children under five, and elderly individuals are more likely to suffer from severe Leptospirosis. it is bacterial ( treatable by antibiotics)it is commonly transmitted when animal urine and wastes end up contaminating drinking water.....(.and where is the pickup line for all their water??? at the bottom of the hill below the pig pens..)..there is a lot of old knowledge that our urban dwellers will have forgot so diseases that killed millions in the 16th and 17th centuries are going to make a comeback


The modern flu is fought through maintaining a stress free environment, bed rest aka inactivity, and keeping yourself clean, aka preventing secondary infections from overwhelming an already occupied/compromised immune system. Secondary infections cause the immune system to divide it's attention. Stress, a mental component, has a high psychosomatic component, resulting in a handicapped immune response. Mind over matter, essentially the placebo effect, is real. Activity wears down body resources, like glucose levels, which are crucial to fighting infections. A tired, afraid person will take longer to fight an infection then someone well rested and calm. It's not just that it's the flu, but the entirety of the circumstances that increases the death toll.

Remember, everyone in the Walking dead is already infected with the Zombie virus. As long as they die with their heads intact they will reanimate. As such, the immune system is already dealing with more than one infection at the time they get the flu. Immuocompromised


First they are already infected with the walker illness. So their immune systems are compromised. It's like how the bite from a walker only kills you, it doesn't cause the walkerism, it's all the bacteria and fungus in their mouths from dying and eating raw meat that will infect a person and kill them: like a kamodo dragon bite.

The flu that is spreading was going around anyway. But with the weakened immune systems they cannot fight it off very well. Like what jfm said about stress and overworking the body. Also Hershel, Maggie and Beth are likely immune because they grew up with farm animals (how they got the flu in the first place) and probably already got the flu a long time ago.


Well Another suggestion is the Actual Infection mentioned in the program which is actually called Pneumococcal by what Dr S Said.

Where it is not actually classed as the flu.


Thus this is true to real life scenario. However this is not the case. Population is infected by the disease that turns you into a walker. So by this statement no matter what your intake is the disease strand mixed with a flu straind your body is weak. Nothing to have to prevent it

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    does the disease really weaken them? are you 100% about this? could you back this up with any canon sources?
    – Daeron
    Commented Feb 3, 2019 at 23:11

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