[Pattern on the spread of novel influenza A (H1N1) and quantitative assessment of containment in mainland China].
OBJECTIVE
To study the epidemic tendency of emerging influenza A (H1N1) in mainland China, and to explore the different patterns of spread on the disease under the following contexts: (1) To stop the temperature screening program at the border areas of the country; (2) To stop measures of prevention and control on those identified cases and their close contacts; (3) To strengthen programs for the foreign immigrants on 'home quarantine'.


METHODS
Under relevant parameters and information on the transmission link from different reference data, the patterns of influenza spread were simulated by Monte Carlo method.


RESULTS
The temperature screening on border could inhibit the transmission of influenza A (H1N1) to some extent, so that after 3 months the cumulative number of cases will be reduced by 21.5% (1718 cases) and transmission speed of influenza A (H1N1) in mainland China will be delayed by about 4 days. Furthermore, taking positive measures of prevention and control could efficiently slow down the epidemic, so that after 3 months the cumulative number of cases will be reduced by 93.4% (about 90 thousand cases) and it would be delayed by about 15 days if influenza A (H1N1) spreads to the whole country. In addition, if the immigrants were able to practise quarantine measures consciously by themselves at home the effect of prevention and control against influenza A (H1N1) would be more significant. If 30%, 60% and 90% of immigrants would take quarantine measures home consciously, after 3 months the cumulative number of cases will be reduced by about 15% (about 940 cases), 34% (about 2230 cases) and 64% (about 4180 cases), respectively. Also, influenza A (H1N1) spreads to the whole country will be delayed by about 4 days, 10 days and 25 days, respectively. It is difficult to curb fully the development of the epidemic by taking existing control measures, and influenza A (H1N1) may spread to almost all provinces after about 3 months.


CONCLUSIONS
The effects of existing prevention and control measures were objectively assessed and the results showed the necessity and effectiveness of these measures against the transmission of influenza A (H1N1), in the mainland of China.
Zhang
Yong
Y
Beijing Normal University, Beijing 100875, China.
Gao
Yan
Y
Fang
Li-qun
LQ
Li
Ya-pin
YP
Qian
Quan
Q
Yan
Lei
L
Yang
Hua
H
Bai
Yan-chen
YC
Zhou
Rong
R
Wu
Hao-ran
HR
Yang
Hong
H
Shu
Yue-long
YL
Cao
Wu-chun
WC
D002681:China / Q000453:epidemiology; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission*; D009010:Monte Carlo Method; D011790:Quarantine