Your question is for instance addressed by:
Amir, Rabah, 2005, "Supermodularity and Complementarity in Economics: An Elementary Survey," Southern Economic Journal, 71, 636-660.
Cournot competition is an example of a submodular game for which an equilibrium exists (under some rather mild conditions though).
You could search on Google Scholar and restrict the range to end in 2019, thus avoiding all Covid-19 related literature.
Some results for the range 1990-2019, keywords "vaccine openness education level":
Lee et al. (2017): Personality and demographic correlates of New Zealanders’ confidence in the safety of childhood vaccinations
Browne et al. (...
There are no set rules for what developed and emerging markets are. Different institutions whether public or private might have different definitions.
This being said you should not just decide arbitrarily about which country you assign developed or emerging status otherwise that would become weak point of your research.
You can either use definitions used ...
Following Galí (2015, p.3) the RBC model rests in three major assumptions: i) the efficiency of business cycle, ii) technology shocks as source of economic fluctuations, iii) the limited role of monetary factors. The main flaws may come from i) and iii), in a nutshell iii) implies that monetary policy (and broadly monetary factors) are fully neutral in ...