What's So Bad About Feeling Good [1968 - USA] comedy

In New York City, the former advertising executive Pete has a become a misanthropic artist following the bohemian lifestyle of the beatnik subculture. He lives in a commune full of melancholic people who are patiently waiting for the end of the world, thanks to the preaching of the leader of a local doomsday cult. One day, a single toucan arrives in the city as stowaway in a Greek boat transporting fruit from South America. The toucan is the host of a contagious virus which spreads intense feelings of happiness, and kindness. After being infected, Pete feels a purpose in his life for the first time. He decides to infect his girlfriend Liz, the entire commune, and most of the population of New York City. He unintentionally destroys the city's economy, because the infected residents suddenly stop buying alcohol, tobacco or drugs. New York's stock exchange and its business districts are about to collapse because the infected are not in the right state of mind to operate them. The political leaders approve an urgent vaccination program to turn New Yorkers back to their natural nasty behavior.