The program does not offer written directions, so pay attention.
It is not easy to explain: the object is to kill the blue virus with the blue gas by opening and closing gates. If a room holds blue gas and you open the door, that gas will fill up the remaining area and will disappear with the dead virus.
You will need to save some blue gas in another room.
Vaccine Case Lite has 12 levels - the last few are hard. I have solved them all.
Vaccine Case Lite easily moves onto the list of Best Puzzle Apps of 2012.
Next week I will report on the full version which has 100 levels.