Correction please."effective ON/IN/TO/ABOUT/FOR humans? Q. I made a sentence below. Is this all correct sentence? ☞ It has been two weeks since they have commenced human trials, but eventually, it will turn out that the vaccine is not effective on humans. I also wonder if besides use of "ON", there is another prepositions alternative? For instance : effective ON something/someone effective IN something/someone effective TO something/someone effective ABOUT something/someone effective FOR something/someone Do these all work? Please choose all that is correct.