The question is not why do we contract the flu in the winter. The question is why does the flu keep re-occuring every year like clockwork? It’s because China is a cesspit, that’s my contention. They still partake in open air meat markets, they have barbaric standards for public health and the way they keep any livestock. Its nothing more than a breeding ground for viruses to mutate and infect people. All these flu viruses stem from chickens and pigs.
Just because China has sophisticated modern architecture, doesn’t translate to the way their human population lives. They are still centuries behind western civilization.
The reason the flu keeps reoccurring is because it keeps mutating. This is the same reason we can't do away with the common cold. Thus, you can't create a vaccination that lasts forever. And, not everyone gets a flu vaccination. So, even in the summer months when flu transmission is low, it still gets passed around somewhere.
Some people are confused by this. They see modern equipment in some Chinese hospital on the news and think their health care system is 1st world like ours. When in reality, it's still a 3rd world health care system in many ways.
Primary care is delivered mainly through village doctors and health workers in rural clinics.
Historically, in rural areas, most healthcare was available in clinics providing rudimentary care, with poorly trained medical personnel and little medical equipment or medications, though certain rural areas had far higher-quality medical care than others...[8][9][10][11][12]
https://en.wikipedia.org/wiki/Healthcare_in_China
It's no wonder at all, that 99.8% of the deaths for this new coronavirus occur in China.