I've got flu - signed off work for a week and it seems I'm recovering well, but the first few days in were terrible. I've never had the vaccine and I'm planning to have it for next season although where I live I'll have to pay for it. My doctor says that it doesn't always work, but he says this year it has been working well. I don't want to go through this again (nearly passing out on day two) Are there any downsides to the vaccine?