Actually this has happened to me twice this year which is really odd because I don't get sick as often as I used to. Quoting: BAD WOLF
Both times it was something to do with respiratory problems.
Infact it's been a few good years since anything made me sick. Might be because of all of the times that I drank green tea or a version of green tea years prior, though.
Usually it's just allergies if it's anything.
It's a little strange that this many people have had something similar.
It is most likely bad air that's causing this, but wonder why this year? We usually do have bad air or air pollutants.
Which would make it a little odd that if you're usually healthy why now? Our air having more pollution? Something to do with our immune systems? Galactic center energy? People becoming more sensitive to what's in the air/food/what we drink? A combination of everything? Who knows.
It is still strange.
Seasonal epidemics happen when a disease in endemic
. That's when it's taken a hold on an area. It's a medical word you don't hear everyday. For example malaria is endemic to certain parts of Africa. West Nile has become endemic now in some states in the USA.
Then certain strains of pathogens get stronger in certain years. They exchange nuclear material. Here's a explantion of how viruses evolve.
[link to www.historyofvaccines.org
I'm not a proponent of flu vaccines by the way, but that's a good layman explanation at that link.
The stronger strains, if there are seasonal things like bad winters in one place, then the people there are weaker from it, and a virilent virus might infect more people.
Because we travel so much, especially air travel, it's easy for a virus to travel throughs hubs very quickly and get disseminated into everywhere.
So a bad virus in India, might quickly go to Pakistan, then on and on.
In the last pandemic, it probably started in Mexico. Then the USA, then it was easy to go everywhere because of air travel. I can hear the Mexican jokes coming, but that's silly. They can happen anywhere, and in history a virus can be named for a nation like the Hong Kong flu.
That was a serious H3N2 influenza type A virus pandemic level 2 one.
[link to en.wikipedia.org
If you read that link, it talks about antigen shift, which is the mutation exchange of nuclear material (resortment).