There is ample evidence since at least World War I, that both 'positive' PSA type information and 'negative' propaganda/counter information/psy ops absolutely have an effect.
Reminder that the Wakefield fraud in 1998, on M.M.R. vaccines and autism, started a negative sentiment towards vaccination and is directly attributed to the measles outbreaks (and deaths) across the developed world (Amplified by Oprah's platform). [1]
Reminder that still today many people will claim carrots give you better vision (they are indeed healthy). This was a counter-info operation from the British, claiming they were providing Air Control with carrots, in order to hide the existing of newly invented RADAR technology against German Bombers. [2]
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136032/
[2] https://www.smithsonianmag.com/arts-culture/a-wwii-propagand...