In its approach, China had essentially detonated a social nuclear weapon. And so it was able to stop the spread of the virus. By late March, the number of new reported cases in the nation dropped from thousands per day to less than fifty per day.35 By April, the daily case count hit zero, and this in a country of 1.4 billion people.

In fact, in many cases, it seemed that the one to two days before a person manifested symptoms was when COVID-19 was possibly most contagious.

Because the SARS-1 pandemic is well behind us, it is very easy to compute its CFR by simply dividing all observed deaths by all observed cases. Since the disease killed 916 out of 8,472 people that came to medical attention worldwide, that’s a crude CFR of 10.9 percent. But for some populations, such as elderly people in Hong Kong, as many as 50

So, early in an epidemic, it is hard to know the CFR. Still, most authorities, using a broad array of data, samples, and methods from countries around the world, concluded that the overall CFR for COVID-19 was in the range of 0.5 to 1.2 percent. Since roughly half (or more) of patients with SARS-2 are asymptomatic, this meant that the IFR was half

Another ship, the Diamond Princess, was quarantined in Yokohama, Japan, on February 3, and it would play a crucial role in the epidemic, providing scientists with a kind of grim natural experiment. Despite how critical experiments are to scientific knowledge, there are many situations in which scientists cannot do experiments for practical or

The time between when a person is infected and when he or she shows signs or symptoms is called the incubation period. This ranges from two to fourteen days in SARS-2 (hence the recommended fourteen days of isolation) and is typically about six to seven days. For SARS-1, the incubation period was shorter, ranging from two to seven days. But there

“Closed-off management” involved many features.30 People were required to shelter in their homes and were given permission to leave only once or twice a week for essentials. Shoppers waited in lines and kept six feet of separation between themselves and others—a development that stunned both local and foreign observers familiar with the usual press

Since there are numerically so many more domestic than international travelers, it should not be surprising that the domestic risk is greater. These scientists concluded that the imposition of restrictions on international travel had a limited effect on the virus’s spread.

The latent period is often shorter than the incubation period in SARS-2, but that was generally not the case in SARS-1. The difference between the latent period and the incubation period is sometimes known as the mismatch period; it’s calculated by measuring the incubation period and subtracting the latent period. The difference between these two