Every year from November to April is the specific season of influenza infection. The flu is more contagious than the common cold and has a high mortality rate. Influenza is a viral infection caused by influenza viruses, and influenza patients are the main source of influenza infection. It is mainly transmitted by humans. The virus can directly infect people who come into contact with the air, and can indirectly infect others through contaminated things. The crowds gather, or the air is not circulating where the virus spreads the fastest.
The vaccine acts by introducing antigens, which stimulates your body to make antibodies against the disease. When you are exposed a second time to the same antigens (by way of coming into contact with the actual flu virus), your body is able to recognize the disease, and the antibodies go into action to prevent you from getting the flu, or to lessen the symptoms and duration by basically beating down the virus.
Tamiflu isn't a vaccine, nor a substitute for a vaccine. Tamiflu CAN be taken if you're exposed, or very soon after symptoms start. It's an anti-viral, which acts to stop the replication of the virus. Tamiflu can also shorten the duration, but not by much - it's estimated that it shortens it by one day. If you've ever had the flu, you know you'd still be grateful for that one day of relief! It's still better to try to prevent the flu via the vaccine, of course.
If you're trying to mask up to prevent getting the flu - and who could blame you - then look for an N95 respirator mask. It's way more effective than a regular paper/surgical mask.
Good luck, and I agree with you! Stay at home if you're not well.