I got a flyer a few months back offering a more generic product, which I think is the same that you acquired. I have used the Boiron product and it has worked well for symptom relief for the following: severe fatigue with chills and all-body muscle aches. It helped me get through the workday a few times last Autumn. I've tried it for bad colds, were the above symptoms weren't present and got no relief. It is very expensive if used according to directions. I bought the 6-vial package for around $12 US, kept one vial for home, one for work and gave the others to friends. The vials contain a shower of sac lac flakes which are supposed to be one dose altogether but I only use one tiny flake at a time and don't repeat unless the symptoms return. A water remedy preparation of one flake worked just as well. This one vial could last me for years which, of course, raises an issue about how remedies are merchandised.
About the flu, a colleague recently suffered severe flu symptoms and got immediate relief from nux vomica 30C, which she believes may be her constitutional.