The most heat sensitive vaccine is -

due to increasd sensitivity to heat,nowadays oral polio vaccines are available as stabilized vaccines.they can be kept at 4 degrees without losing its potency for a year.in case of non stabilized vaccines,t must be kept at -20 degrees till use.inorder to keep a check on heat induced damage to the vaccines,nowadays vaccine l monitors are widely used.it has to be kept cold during transpoation also by keeping on dry ice. ref:park&;s textbook,22 nd ed,pg 189