Chicken pox can occur twice, but it is really rare. Most of the time a second occurence happens in people with compromised immune systems be it from age or other underlying issue. A second occurrence is generally very bad and usually requires hospitalization.

http://www.hopkinsmedicine.org/healthlibrary/conditions/infectious_diseases/chickenpox_varicella_85,P00619/ (not key word "most" people will be immune)
http://www.immunize.org/catg.d/p4211.pdf (page one bottom right*)

Not sure your source but you need to check again.
If you want to challenge my sources then go ahead find your own but read them carefully.

This post was edited by King Atrhur on Nov 4 2015 06:10am

but how u define weak matters, depends what u r referring to

and depends on what "event" would cause population decline? there other other evens aside from disease

humans survive using much more complex ways than other wild animals

All in all it doesn't matter. Between the Service and the VA, I've had shots for everything under the sun, and they keep them up to date.

What I'm saying is that complex way is the medicine and hygiene standards.
As for the event take any disease we now have a vaccine or medication to treat.
also the ability to perform such invasive surgery.



Vaccines don't make you immune. they are not 100% but they do help. In the end your still able to get chicken pox.

This post was edited by King Atrhur on Nov 4 2015 08:00pm

Lol, I'd win the lottery, first. :/

not when you don't buy a ticket.