I don't really understand what these calculations are for, but I can confirm in armor with "zombiImmune: true" soldiers never become zombies. In the armor without this parameter, from turning into a zombie saves a "melee Dodge:" when Chryssalid stupidly misses the target. However if he not misses, the trouble can not be avoided, but it's as lucky. In General, the instruments to combat Chryssalid and Tentaculat full.