This sounds just like the hippie lady down the street that would spray echonacha in the back of our throats if we complained of a cough.
Futurology
The approach described in the journal Science does not train the immune system.
[..] leaves white blood cells in our lungs [..] ready to jump into action no matter what infection tries to get in.
The effect lasted for around three months in animal experiments.
This stretches the definition of vaccine, and the effect is pretty short lived. What matter most I guess is that the spray works in clinical trials. It might be helfup to vulnerable people ahead of flu season.
"coughs, colds, and flus would have been eradicated, but right wingers in the US still exists and refuse the vaccine, creating the last reservoir for these ailments."
There are anti-vaccine groups in pretty much every western country. According to the WHO, in 2025, there were 14,064 confirmed measles cases across all of North and South America, meanwhile there were 33,998 confirmed cases across Europe. This is a global issue
Those numbers are meaningless. The population of Europe is about 750M, with a population density of 73/km^2^. The population of the Americas is about 1000M with a population density of less than 25/km^2^. So, if simple population was all that mattered, one would expect more in the Americas. However, if population density matters more, one would expect more transmission, and more cases in Europe. Also, measles vaccination in Europe is 94% while it is 88% in the Americas. That sounds close, but a better way of looking at it is twice as many people in the Americas are refusing the vaccine than in Europe.
This is a global issue, but it's twice as bad in the Americas.
.. and cue the ~lobbying~bribes to outlaw this entire line of research, paid for from the makers of Neo-Citran, Nyquil etc.
Being always hyper attentive and alert definitely sounds good for flu season but not for life long protection. That does not seem wise in the slightest. IIRC that's exactly why we have allergies: some immune responses are always on and over the top against something they recognise incorrectly.
It's not impossible that this will require more energy from the body and lead to marked fatigue in subjects.
Many diseases are also caused by an over-active immune system in one way or another, like Rheumatoid arthritis, Celiac disease, and many others. It's an entire category of diseases.
https://en.wikipedia.org/wiki/List_of_autoimmune_diseases
If this works by cranking your immune system up to 11 and that's it, this won't be good for most people would be my bet. Worst of all, some issues wouldn't show up until years later. Many autoimmune diseases aren't exactly as obvious as the flu.
Could.
Thats… not enough