Lets look at more context while we wait for nostr:nprofile1qqstnem9g6aqv3tw6vqaneftcj06frns56lj9q470gdww228vysz8hqpzdmhxue69uhkzmr8duh82arcduhx7mn9qy2hwumn8ghj7etyv4hzumn0wd68ytnvv9hxgqgdwaehxw309ahx7uewd3hkcam28zl.

Most vaccines are compared to saline as a placebo as demonstrated by the examples above, or this trial on a dengue vaccine (doi: 10.1016/S0140-6736(20)30682-6.) for another example. This is actually the cheaper and less laborious thing to do. In some situations something else is used (e.g. a different vaccine or the adjuvants). For example, if you want to prove superiority or non-inferiority of a new vaccine it makes sense to compare the new vaccine to an established one. Another reason might be ethical considerations. Is it acceptable to withhold an effective vaccine from half of the study population? Regulatory requirements might be a third reason why it could be necessary to use something else than saline.

As with most things in life, when you look beyond the first superficial outrage and excitement there is a lot more nuance under the surface.