I waa going into a song and dance about how Ryanair seem to be ignoring the pandemic. No mention it on their website and only the odd comment via the press. I think they would have you on the plane even if you had Typhus. Bums on seats syndrome.
Contact your TC rep/website. If they have no policy of refusing you on the plane you might not be able to claim unless you have it written in blood by your GP that you cannot travel. Personally it would not stop me. I think most of us will get the flu sooner or later so lets get it over with and we can all live a life again