Table 1. Pearson correlation coefficients between search terms from Baidu search engine and the number of influenza cases in Liaoning, for the time period January 2011–December 2015.

Search terms	The same month	Lag one month	Lag two months	Lag three months	Non-flu season
Flu	0.608**	0.536**	0.500**	0.395**	0.672**
Flu symptoms	0.618**	0.374**	0.273*	0.04	0.430*
Influenza type A	0.489**	0.134	0.005	−0.287*	0.048
Influenza vaccine	0.259*	0.436**	0.645**	0.764**	0.328
Is it necessary to get vaccinated against the flu?	0.103	0.362**	0.626**	0.814**	0.255
Flu virus	0.621**	0.435**	0.282*	0.175	0.711**
The symptom of flu	0.656**	0.438**	0.209	−0.054	0.235
Influenza drugs	0.639**	0.431**	0.218	−0.116	0.337
The symptoms of type A flu	0.157	0.029	−0.061	−0.225	0.320
Prevent flu	0.623**	0.644**	0.663**	0.511**	0.374*
Swine flu	0.371**	0.290*	0.172	0.075	0.459*
H1N1 flu	0.021	−0.157	−0.231	−0.409**	−0.302
Beijing flu	0.249	0.055	0.037	−0.148	0.313
Swine flu symptoms	0.032	0.142	−0.104	−0.101	−0.039
How to prevent flu	0.023	−0.025	0.056	0.007	−0.006
Viral flu	0.484**	0.339**	0.234	−0.023	0.587**
How to prevent flu	0.129	0.087	0.201	0.125	−0.014
Spanish flu	0.459**	0.479**	0.405**	0.409**	0.491**
Flu prevention	0.178	0.012	−0.092	−0.133	0.380*
Side effects of flu vaccine	0.084	0.379**	0.657**	0.804**	0.254
The prevention measures of flu	−0.079	−0.056	0.043	0.061	−0.108
Type A H1N1 flu	0.089	−0.024	−0.281*	−0.362**	−0.379*
Flu therapy	0.438**	0.183	0.168	−0.075	0.291
The prevention of flu	−0.335**	−0.357**	−0.251	−0.285*	−0.394*
Influenza epidemic	0.09	−0.075	−0.207	−0.375**	0.108
Influenza vaccine price	−0.273*	−0.185	−0.002	0.126	−0.124
Type A flu	0.383**	0.326*	0.025	−0.193	0.508**
Type A flu virus	0.586**	0.395**	0.276*	0.002	0.369*
New type of flu	0.352**	0.430**	0.037	−0.076	0.387*
Type A influenza	0.016	−0.222	−0.138	−0.345**	−0.197
Love flu strain	0.054	−0.165	−0.166	−0.296*	−0.425*
Flu concept stock	0.266*	0.226	0.011	−0.072	0.349
Seasonal influenza	−0.046	−0.122	−0.12	−0.172	0.515**
Love flu	−0.300*	−0.310*	−0.350**	−0.368**	−0.114
Type A H1N1 flu virus	−0.109	−0.22	−0.24	−0.131	−0.160
New flu	−0.048	−0.064	−0.151	−0.25	−0.016
How to treat swine flu	0.223	0.547**	0.476**	0.381**	0.200
Influenza transmission route	0.228	0.1	−0.09	−0.076	0.346
The route of transmission of flu	0.216	−0.011	−0.12	−0.164	0.207
Treatment program of A type H1N1 flu	−0.145	−0.19	−0.24	−0.304*	0.102
Flu (space) symptom	0.147	0.042	−0.068	−0.157	0.358
H1N1 flu symptom	0.346**	0.196	0.141	0.064	0.260
Sheep flu	0.011	−0.038	−0.053	−0.107	0.211
Super flu	0.314*	0.248	0.133	0.16	0.172
The symptom of swine flu	0.134	0.071	−0.025	−0.124	0.341
Taiwan flu	0.124	0.066	0.104	−0.188	0.374*

Notes:

^*Indicates the P value with statistically significance at 0.05 level.

^**indicates the P value with statistically significance at 0.01 level.