Rule of thumb... Multiply by 10 those who were ill, and thinking whether they should go to the hospital. And multiply by 10 once again to get the number of mildly ill after the shot.

In other words, 1 of 10, at least, felt sick after the shot (all of my friends did, I haven't taken it)
1 of 100 was in very, very bad shape
1 of 1000 ended up in hospital

Serious numbers. Not good