| 
      Chi-square=2.301 P=0.0316 P<0.05Significant
        | Age group | No. | No.+VeIgG | No.+VeIgM | Death 
                death | Chi-square | P-value |  
        | 20-25 | 10 | 1 | 4 | 1 | 2.001 | 0.056 NS
 |  
        | 26-30 | 10 | 2 | 5 | 2 | 2.136 | 0.048 S |  
        | 31-35 | 10 | 5 | 2 | 2 | 2.135 | 0.048 S |  
        | 36-40 | 10 | 6 | 2 | 3 | 2.365 | 0.043 S |  
        | 41-45 | 10 | 7 | 3 | 4 | 3.024 | 0.041 S |  
        | Total | 50 | 21 | 10 | 12 | 2.301 | 0.0316 |  |