. 2016 Jun 30;2016:5253842. doi: 10.1155/2016/5253842

Table 3.

Percentage of cases classified in concordance with PRNT classification, using IgG ELISA, WHO HI criteria, or modified HI criteria.

	IgG ELISA	WHO HI criteria	Modified HI-1^a	Modified HI-2^b
Primary infection	16/16 (100)	16/16 (100)	13/16 (81.25)	10/16 (62.5)
Secondary infection	72/73 (98.6)	23/73 (31.5)	68/73 (93.2)	64/73 (87.7)

^aPrimary infection if convalescent HI antibody titers are ≤80 or if convalescent HI antibody titers are 160, 320, or 640 and HI antibody titers negative in acute specimen; ^bprimary infection if HI antibody titers are negative in acute specimen.