Seems this is the only vaccine on the market and would like to ask a couple of questions before buying. My main question is do you have to vaccinate them twice? I seem to recall that is the case but my memory isn't the best these days, old age kicking in me thinks. If you do have to vaccinate them twice can this vaccine once opened be kept in the fridge. It would be appreciated if anyone has got the data sheet that come with the vaccine could answer these questions. Thanks in advance Tony