I came across this question that asks "What verb would you recommend with 'interest' to mean “increase”?", but I wonder what would be the opposite of it. The answer to that question recommends spark, boost, amplify, surge, escalate etc. I also searched their antonyms but didn't find an idiomatic one.
So in the sentence
The pandemic [verb to mean "decrease"]ed the people's interest in epidemiology
Suggestions have already been provided. I would just add some more to the list, especially the ones I use.
The pandemic lowered the people's interest in epidemiology.
The pandemic dwindled the people's interest in epidemiology.
The pandemic toned down the people's interest in epidemiology.
The pandemic dampened the people's interest in epidemiology. (dampen is already suggested by someone earlier. Credits to them.)
You can actually use a lot of verbs to express a "lack of interest" in something, here you have some examples: Verb to express a Lack of interest
I would personally use the verb suppress:
The pandemic suppressed the people's interest in epidemiology
Otherwise you can use this sentence to express a minor interest of people about epidemiology:
The pandemic decreased the interest of people about epidemiology
Some options are: lessened, dampened or diminished
You should be able to find many more options by looking up synonyms of these. For example: https://www.thesaurus.com/browse/lessen
Some of the options given may not be fully appropriate but you should be able to look each one up to decide if it fits what you want to say.
