A deadly super flu gets out and kills 90% of the population. During the exponential spread of the virus, it infects people working in a military base that deals in bio weapons. Is there a way to calculate the statistical probability of another virus escaping during the panic and further depleting the population?


I was watching The Walking Dead and about three seasons into it I realized that despite that deadly flu in the prison, no one was catching diseases. In a scenario for the zombie apocalypse, one would think that at least one govt. weapons lab might have a leak due to panicky scientists who realize the world is ending.

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    $\begingroup$ Most diseases spread by person to person - very few work airborne over vast distances. Therefore a reduced population will equal reduced disease spreading - it might even wipe out some other diseases. $\endgroup$ Mar 11, 2015 at 18:59
  • $\begingroup$ @DanSmolinske I mean, you would think that someone evacuating a research lab who is contaminated with super Ebola would escape and spread it to a lot of people during the pandemic and initial panic. $\endgroup$
    – Jax
    Mar 11, 2015 at 19:01
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    $\begingroup$ Dustin - that ebola would quickly die out though. The most "successful" pandemic viruses would be ones that do not kill or severely hamper their hosts, are transmitted through air, and which have a long incubation period. $\endgroup$
    – David Rice
    Mar 11, 2015 at 19:06
  • $\begingroup$ I guess there is a reason rabies hasn't 'caused the zombie apocalypse' like conspiracy theorists think. $\endgroup$
    – Jax
    Mar 11, 2015 at 19:11
  • $\begingroup$ Don't virus's compete when they are present in the same host? $\endgroup$
    – Twelfth
    Mar 11, 2015 at 19:39

1 Answer 1


Bioweapons and the like are under extraordinarily paranoid controls. Even a panicking scientist -- or group thereof -- practically has to try really hard to get it out into the wild.

However, secondary diseases would almost certainly be a reality. As society breaks down, we're going to lose access to clean water, and see a spike in waterborne illnesses. Medical infrastructure will fail, so things like the "regular" flu will become more serious issues and will more readily spread with the loss of access to annual vaccinations. Diseases that are fairly common but easily treatable will still be at least as common, but become much more deadly -- pneumonia, for instance, can usually be treated well in a hospital and has a high survivability as a result, but without access to hospital treatment the odds of someone who catches it surviving dwindle rapidly (further compounded by lack of clean water, food, etc.).

Measles, mumps, and rubella will return, albeit not for a few years (gotta work out the "herd immunity" of those already immunized), and will again be serious illnesses.

On the other hand, with fewer people (presumably spread out across vast distances), widespread pandemics would become very difficult -- but individual enclaves could easily be wiped out entirely (or at the least suffer local epidemics) by diseases you or I today consider minor inconveniences at best.

The end result is that if your disease wipes out 90%, you can pretty much bet that a good chunk of those who somehow survive yours will nonetheless succumb to one or more of the many other diseases that suddenly become big deals again.

  • $\begingroup$ If survivors form large-ish groups, you'd almost definitely see more of common illnesses like colds initially; part of the reason they're so common in winter isn't the cold itself, but the fact that we're indoors more so we're all in closer proximity to each other. Whether you'd keep seeing them indefinitely depends on the size of the group and the rate of mutation. $\endgroup$ Mar 11, 2015 at 19:05

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