1919
Protection levels of 33 . 3 % , 36 . 6 % and 37 . 0 % were achieved in groups which had received , respectively , 1000 20 - krad cercariae , 1000 10 - krad cercariae , 2000 40 - krad cercariae and 2000 60 - krad cercariae .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 None