Popular science: what is a "pandemic"
Xinhua News Agency, Beijing, March 12th: World Health Organization Director-General Tan Desai announced in Geneva on the 11th that the new crown pneumonia epidemic "can be characterized as a pandemic". So what is a "pandemic"?
The "pandemic" was originally one of WHO's ratings for influenza. WHO categorizes influenza into six levels, the highest of which is a "pandemic", which is defined as a community-level outbreak of an influenza virus in at least one country other than the place where the outbreak originated, indicating that the virus is spreading across countries.
Conceptually, the "pandemic" at the time referred to the scope of the influenza virus, not the severity and lethality of the epidemic. In 2009, the outbreak of H1N1 influenza from the United States and Mexico was classified as a "pandemic" by WHO, which has caused a lot of controversy, although this influenza has spread worldwide, but the fatality rate is low, which is more serious than people think. Infectious diseases are inconsistent.
Therefore, the WHO website in 2010 gave a simple definition of "pandemic", which is "a new disease spreading worldwide." For example, an influenza pandemic refers to the spread of a new influenza virus subtype worldwide, and most people are not immune to the virus. This time, New Coronary Pneumonia became the first coronavirus infection known as a "pandemic."
At present, WHO no longer uses the above-mentioned 6 classifications to evaluate infectious diseases such as influenza, but instead uses 4 major stages. WHO spokesman Jasarevich said in an interview in late February that WHO no longer uses this old system, but people still use the term "pandemic" to describe the global spread of infectious diseases .
It can be seen that "pandemic" is not a strict definition but a vague concept with operational flexibility. Tan Desai said on the 11th that describing the current epidemic of new crown pneumonia as a "pandemic" will not change WHO's assessment of the threat of new crown virus, which will not change what the World Health Organization is doing, nor will it change countries. What should be done.