Table 4. The comparisons for the differences in coughing scores as assessed by the researchers among the four groups by the Kruskal—Wallis test.

Parameters	IFN Injection	Control	IFN Nebulization 1	IFN Nebulization 2	χ2	P
The differences of researchers’ coughing scores of days 1 and 3	1.88±0.16	1.32±0.10	1.58±0.13	2.07±0.14	14.105	0.003
The differences of researchers’ coughing scores of days 3 and 5	2.04±0.12	1.59±0.12	2.07±0.11	1.96±0.13	12.940	0.005
The differences of researchers’ coughing scores of days 5 and 7	1.87±0.14	1.48±0.10	1.47±0.13	1.38±0.20	3.834	0.280