Depending on what type of pill you are on , it may not have been effective immediately anyway. Most are not effect until you have been taking them for seven days anyway but the mini pill is effective immediately as far as I am aware. In any case , I would definitely suggest using extra contraception such as condoms in the meantime just to be on the safe side , as if you have been vomiting or suffering from diarrohea , then the chances are it may well have affected your pill taking. As Crete suggests though , read the accompanying leaflet to your pills for more accurate information and if you are still in doubt , consult your GP when your surgery is open again.