Projected to complete in May. Of course, if they have significant results I'm sure they'll report them early, just like all other vaccine trials to date.
Cool! You have to be very careful with what you find on clinicaltrials.gov. Not because it contains misinformation, but usually because it contains only the barest bones of information. For example, here it is saying that ENSEMBLE 2 is projected to "complete" in May. Does it say what completion means? Of course not. This may be the longest time they're planning to do solicited safety reporting, or it may be an estimate for when they originally expected to get their full number of disease events. You're right that they may well report earlier than that.
However, it won't be based on whether they have significant results or not. Remember, these are blinded trials. The analyses are prespecified and they are only triggered by prespecified conditions. Usually for a vaccine trial, that condition to trigger analysis is based on a specific number of total disease events, across all trial arms, with the number being chosen based on a desire to achieve about 80% statistical "power" to detect an effect on the primary endpoint. For those who don't read clinical trial statistics all the time, this is a number of events that lets them be about 80% confident that IF there is an effect, they will probably be able to see that effect in the results.
Anyway, they give an estimate for the trial completion, but since it's event-driven, there's no way to know in advance when it will end.
Being event-driven makes the design less prone to bias, though--this way, the folks running the trial don't have any control over the exact period of the trial that is used to analyze the data. The event-driven approach means they must look at a specific period of time, they must perform the analysis they planned before they knew the results, and they cannot manipulate the time window or analysis methods, even subconsciously, to get the result they would prefer to see. Trial sponsors choose this kind of approach in advance to make sure the results are convincing and unbiased.
Don't know if you're interested, but I found the details of the ENSEMBLE 2 trial at clinicaltrials.gov: https://clinicaltrials.gov/ct2/show/NCT04614948
Projected to complete in May. Of course, if they have significant results I'm sure they'll report them early, just like all other vaccine trials to date.
Cool! You have to be very careful with what you find on clinicaltrials.gov. Not because it contains misinformation, but usually because it contains only the barest bones of information. For example, here it is saying that ENSEMBLE 2 is projected to "complete" in May. Does it say what completion means? Of course not. This may be the longest time they're planning to do solicited safety reporting, or it may be an estimate for when they originally expected to get their full number of disease events. You're right that they may well report earlier than that.
However, it won't be based on whether they have significant results or not. Remember, these are blinded trials. The analyses are prespecified and they are only triggered by prespecified conditions. Usually for a vaccine trial, that condition to trigger analysis is based on a specific number of total disease events, across all trial arms, with the number being chosen based on a desire to achieve about 80% statistical "power" to detect an effect on the primary endpoint. For those who don't read clinical trial statistics all the time, this is a number of events that lets them be about 80% confident that IF there is an effect, they will probably be able to see that effect in the results.
Anyway, they give an estimate for the trial completion, but since it's event-driven, there's no way to know in advance when it will end.
Being event-driven makes the design less prone to bias, though--this way, the folks running the trial don't have any control over the exact period of the trial that is used to analyze the data. The event-driven approach means they must look at a specific period of time, they must perform the analysis they planned before they knew the results, and they cannot manipulate the time window or analysis methods, even subconsciously, to get the result they would prefer to see. Trial sponsors choose this kind of approach in advance to make sure the results are convincing and unbiased.