Not a vaccine.
At the risk of repeating myself, a company I worked at recently had 3 floors of employees who lost what amounted to years of man-hours at work due to a flu epidemic. I sat by sipping my herbal tea watching while entire floors called in sick and the whole company was depopulated for weeks at a time. Nearly every single employee was out for a week or more, setting the company back months and months in many of their projects.
I had people sneezing right in my face, sneezing in the kitchen, coughing violently a meter away, coughing on my lunch, coughing on their desks. I never did get sick.
The only thing I could find in common with a buddy of mine who sat on the same floor in this huge empty office was that neither one of us had taken advantage of the free flu vaccination offered to all staff for this firm.
After a couple months watching this, I began to develop a feeling of near invulnerability. I had actually gained 14 kilos of muscle (age 48, no steroids) during this time. One night at the gym, realizing I had forgotten to bring my belt, I did ass-to-calves squats followed by hack squat with well over a metric ton on the stack. Ha, I thought. I don't need no steenkin' belt. My ginormous superhuman neanderthal muscles laugh at belts and other puny human tools to shore up their feeble physiques. As if my superhuman frame and bone structure needed support from a tiny piece of leather to go around my waist.
I threw my back out so badly I have been bedridden for more than three weeks and had to take enough painkillers to put a draft horse down at a veterinarial clinic. I was unable to sleep much for the first week and only lately has it begun to settle down.
Success breeds failure because it leads to hubris and arrogance. Tex is a little less vulnerable to this kind of foolishness than most but after all, I am only human. You'll never see superman lying in bed moaning and asking his wife to help him get his socks on.