Trust. If one study is from the Institute for Tobacco Studies and the other from Harvard I would trust the one from Harvard and stop smoking.
Right now though it's Harvard and 163 other parties each hoping that their patented-sequence still-totally-unknown product will be the one the entire world rushes to purchase: https://www.who.int/publications/m/item/draft-landscape-of-c...
I know your Harvard example was hypothetical, but for what it's worth here's Harvard's actual COV*D trial: https://clinicaltrials.gov/ct2/show/NCT04436276?term=NCT0443...
It's listed under Janssen, but you can read about the relationship here: https://news.harvard.edu/gazette/story/2020/04/harvards-coro...