ABSTRACT
OBJECTIVE：To evaluate the price and affordability of rare disease drugs in China and provide the suggestions for the improvement of rare disease drug affordability in order to provide reference for the relevant decision-making of government departments. METHODS ：According to the List of the First Batch of Rare Diseasesand Diagnosis and Treatment Guideline for Rare Diseases（2019 edition），rare disease drugs were selected. The median price ratio （MPR）was used to evaluate the drug price level ， and the ratio of the annual drug costs to the annual disposable income of urban or rural residents was used to evaluate the affordability，and the impact of price management policieson drug prices and affordability. RESULTS and CONCLUSIONS ：A total of 71 kinds of rare disease drugs were included ，and the median MPR of them was 0.83；among them ，the median MPR of the original drugs was 1.13，and the median MPR of the generic drugs was 0.37. The annual cost of 71 rare disease drugs was 0.001-178.43 times the average annual income of urban residents ，and 0.003-456.57 times the average annual income of rural residents. There were 21 and 28 drugs whose annual cost exceeded the annual income of urban and rural residents.After the implementation of national medical insurance negotiation or volume based procurement of 14 drugs，the median MPR of these drugs decreased from 1.71 to 0.46. For urban residents ，the number of unaffordable drugs had been reduced from 8 to 0；for rural residents，it had been reduced from 10 to 5. In summary ，the price level of orphan drugs in China was slightly lower than international reference price ，but the price level of original drugs was higher than the international reference price ，and the cost of some drugs far exceeded the residents ’ability to pay. It is suggested that the government should strengthen the price management of original drugs ，promote the substitution of high-quality generic drugs for original drugs ，and improve the payment system for high-value rare disease drugs.
ABSTRACT
To analyze the molecular basis of the variation of the pathogenicity of the influenza B virus, we rescued a recombinant virus with a deletion in the carboxyl terminal of the NS1 protein using reverse genetics based on the parental virus B-S9 of B/Yamagata/16/88. A mutant strain with a deletion of 171 amino acids in the carboxyl terminal of the NS1 protein was named "B-L5". BALB/c mice were inoculated with 3 X 105 EID50 of B-L5 and the parental virus B-S9, respectively. Then, weight changes, survival, and viral titers were documented. During 3 days post-inoculation (dpi) to 7 dpi, the weight of mice infected with B-S9 decreased. However, the weight of mice infected with B-L5 showed weight decreases only at 2 dpi, and quickly recovered at 3 dpi. B-S9 and B-L5 could replicate in the lungs of BALB/c mice. However, viral titers in the lungs of mice infected with B-L5 were 7900-times lower than those of mice infected with B-S9 at 3 dpi. Viral titers in the lungs of mice infected with B-L5 were not detected at 6 dpi. These results showed that, compared with the parent virus B-S9, the mutant virus B-L5 showed lower pathogenicity in BALB/c mice. Our study suggests that deletion of the carboxyl terminal of the NS1 protein decreases the pathogenicity of the influenza B virus. Establishment of a reverse-genetics system for the B influenza virus will provide a platform for studying its pathogenesis, and mechanism of transmission, and for developing live-attenuated influenza B virus vaccines.