In this article, "The Clinical Features of 2019-nCoV Infected Patients," published in The Lancet on January 24, we can understand the specifics of the 41 patients who were diagnosed the earliest.
As of January 22, 28 of the 41 had been discharged and 6 had died. Fever and cough are the most common symptoms, ranging from onset to difficulty breathing, on average 8 days.
In the early days of pneumonia, the signal from person to person was already obvious, and 14 of these 41 people had not visited the South China Seafood Market.
Another paper, Jan. 24, "Familial pneumonia associated with a new coronavirus in 2019, shows human-to-human transmission: a study of family gatherings," examines a Shenzhen family traveling to Wuhan on December 29.
The man with the earliest symptoms began to have fever and diarrhea on the 4th day after arriving in Wuhan, and 3 days later, his wife-in-law and mother-in-law also began to have a fever and cough. On January 5, the family returned to Shenzhen. Four days later, the mother, who had not been to Wuhan, began to feel weak.
In the end, 6 people were diagnosed with new coronary pneumonia in this 7-member family, including his son who had no obvious symptoms.
It is not difficult to spread the coronavirus among close family members.
The first is a sneeze. You will spit out more than 10,000 droplets, reaching a distance of up to 8 meters.
Then there is a cough, 1000-2000 droplets, up to 6 meters.
In the end, even quiet talk produces about 500 droplets per minute.
This is what it looks like 0.34 seconds after you sneeze.
The green ones are those large droplets above 100 microns, and because they are heavy enough, they will land on the ground within 10 seconds. The red ones are fog clouds formed by small droplets.
They quickly evaporate in the air and become smaller, becoming dry droplet nuclei. The epithelial cells are proteins that coat the coronavirus and float in the air, touching other people's mucous membranes.
This January 30 paper further analyzes data from the first 425 confirmed patients in Wuhan.
In this table, the abscissa is the time from infection to onset, and the ordinate is the relative probability. It can be seen that most infected people will get sick within 7 days, and the average incubation period of the virus is 5.2 days.
Now we know that of the 295 people diagnosed before January 11, 2020, only 45 have visited the South China Seafood Market, and there are also 7 medical staff. But after ten days, people realized they were wearing masks.
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