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Assessing hepatitis A virus epidemic stochastic process in eight cities in China in 1990
1Department of Epidemiology, Fourth Military Medical University, Xi'an, P R China.
Background:
In The People's Republic of China in 1990, the age-specific seroprevalence of hepatitis A was investigated in eight large cities.
Methods:
A stochastic model, the two-state Markov chain, was applied to hepatitis A virus seroprevalence data by age group. An age-specific risk rate, Markov Risk Rate (MRR), and its weighted sum, Total MRR, are defined and used as novel measure indices to prioritize age groups for allocating vaccine or to decide in which cities vaccine should be used to prevent hepatitis A.
Results:
In 1990, the MRR1- in Xi'an, Jinan, Ha'erbin and Huhehaote, and the MRR10- in Chongqing were over 40. The MRR10- in Xi'an, Nanjing, Jinan and Ha'erbin and the MRR20- in Chongqing and Nanjing were over 20. The Total MRR in Chongqing and Ha'erbin were over 160, which was higher than the warning value.
Conclusions:
All age groups whose MRR was over 20 are strongly recommended to be vaccinated first. Chongqing and Ha'erbin are cities at high risk of a hepatitis A virus epidemic in the 1990s and therefore should be under close surveillance.