How effective are the vaccines from Pfizer and from Moderna against the COVID-19 coronavirus in preventing infections?

These will be moderate to highly effective, depending on the individual variability in response. So they will perform as intended with respect to having a credible efficacy and therefore value to justify their use. This is not a perfect approach, but is far better than remaining helpless, all other things being equal. As you know, there will be a liability from locator chips being added to facilitate a human annihilation down the line. Those can be neutralized using the Lightworker Healing Protocol, but because their removal or silencing only represent some greater inconvenience for the extraterrestrial roundup and elimination, they will not be a determining factor in human survival. So in and of itself, this is not a reason to avoid vaccination.