On the 25th local time, in response to the second infection of the new crown pneumonia in Hong Kong patients who recovered from the new crown pneumonia, WHO spokesperson Margaret Harris said that only one of the more than 23 million confirmed new crown pneumonia cases in the world was the second after recovery. Secondary infections are not common, otherwise there will be more such cases. The important thing is what this case means for the immune response. There are currently many studies that are tracking and measuring the level of antibodies in the human body to understand the duration of natural immune protection. (Headquarters reporter Zhu He)