The impact of the vaccination program for hemorrhagic fever with renal syndrome in Hu County, China.

The incidence of hemorrhagic fever with renal syndrome (HFRS) in Hu County ranked third of all counties in China in 2010. Although this county has provided a HFRS vaccination program freely since 1994, the impact of HFRS remains quite substantial. In order to continue the vaccination program effectively and control HFRS, a detailed understanding of the effect of the vaccination program should be undertaken. The Cochran-Armitage trend test was employed to examine the temporal trends of HFRS incidences, mortality rate and vaccination compliance. Temporal cluster analysis was performed to detect time periods of high HFRS risk. Cross correlation analysis was conducted to detect the correlation between HFRS incidence and vaccination compliance. Wavelet analysis was employed to detect the shift of the periodicity of HFRS. Between 1971 and 2011, the HFRS incidence and mortality rate ranged from 9.53/100,000 to 300.57/100,000 and 0 to 24.91/100,000, respectively, with a fluctuating but distinctly declining trend (incidence: Z=-34.38, P<0.01; mortality rate: Z=-23.44, P<0.01). The vaccination compliance ranged from 4.55% to 83.67%, with a distinctly increasing trend (Z=1621.70, P<0.01). The most likely temporal cluster of the HFRS epidemic was between 1983 and 1988 (RR=3.44, P<0.01) or 1979-1988 (RR=3.18, P<0.01) with different maximum temporal cluster size. There was a negative correlation between HFRS incidence and vaccination compliance when the lagged year was 1 and 2 (cross correlation coefficient=-0.51 and -0.55). The periodicity of HFRS epidemic was prolonged from about 5 years during 1976-1988 to 15 years after 1988, especially after the start of HFRS vaccination in 1994. In conclusion, the increase in vaccination compliance may play an important role in HFRS control and prevention in Hu County, China.