Pretty much ever trial will have a top and bottom group. If you take the top of them, it will (most likely) look impressive. For this, how did they survive those first two to three years? Was it due to the vaccine or because they were amongst a highly selected population among other things? My view is the latter, but either way, compared in an RCT will inform, while to historical controls will only mislead (which is what this company is now doing for pretty obvious reasons).