In addition, there are many differences between the two viruses in terms of virus transmission, clinical symptoms and treatment.

For 2019-

CoV, scientists are racing to find out more.

In the process, our understanding of the virus and its threats will also change.

So, next to 2019-

The description and discussion of CoV is based on what is known to date.

Contagiousness

An important reason for the rapid spread of the COVID-19 epidemic is that 2019-

CoV is highly contagious.

Scientists often use the "basic infectious number" (R0) to assess how easily the virus can spread.

In layman's terms, it is to assess how many people a patient infected with a certain infectious disease can infect on average.

The higher the R0 value, the more contagious the infectious disease is. According to the New York Times, the R0 value of the influenza virus is about 1.3.

And for 2019-

R0 of CoV, researchers are still trying to determine. A study published Jan. 29 in the New England Journal of Medicine (NEJM) estimates.

But just today, a paper published on this preprint website pointed out through the analysis of nearly 9,000 cases that in 2019-

The R0 of CoV reached 3.77.

That is, on average, each infected person can infect 3.77 people with the virus.

If this conclusion is confirmed, it means that 2019-

CoV is far more contagious than previously expected.

It is important to note that R0 is not a fixed constant for each disease. R0 varies from region to region, depending on how often people come into contact with each other, and the intensity of containment measures.

Seeing these data, Lingxi gasped.

How can it be so serious? It feels completely beyond the control of human beings!

What the hell is going on? She's been thinking about it all the time!

Moreover, this time the virus spreads so fast and is very contagious!

She looked at the news again, and now, over there, many cities in the United States have been locked down!

People are forbidden to come and go to each other to avoid spreading the virus to each other! So, their schools have also announced an extended holiday!

So, even if they want to go now, they can't go!

She kept looking!

The length of the incubation period of the virus is also an important factor affecting the ability of the disease to be transmitted.

The incubation period of influenza virus is mostly 1~4 days, while 2019-

CoV is more complex.

The patient became ill as soon as the same day, while one patient reported that it took a 24-day incubation period to show symptoms. Patients with a long incubation period pose a challenge to early diagnosis and isolation.

Mode of infection

There are three main ways to transmit influenza viruses from person to person: direct transmission (also known as droplet transmission, which refers to the infection caused by the droplets produced when the patient sneezes, coughs, or talks, and is inhaled into the body by the people around them), aerosol transmission (droplets are mixed in the air to form aerosols, which cause infection after inhalation), and contact transmission (droplets settle on the surface of objects, and after the hands touch the source of pollution, they then touch the mucous membranes of the mouth, nose, eyes, and other parts with their hands, resulting in infection).

The influenza virus attaches to the cells in the respiratory tract, and then, the hemagglutinin (hemaggluti) of the influenza virus

i

Surface proteins bind to sialic acid receptors on the surface of human respiratory tract cells, thereby opening the "lock" of human cells to enter and infect cells.

And 2019-

The human-to-human transmission of CoV is also questionable.

What has been established is that 2019-

The transmission of CoV includes direct transmission and contact transmission, and the evidence for aerosol transmission and fecal-oral transmission is still insufficient. 2019-

Like SARS, CoV enters cells through ACE2 receptors and then infects the respiratory tract.

Symptoms and severity

According to the Centers for Disease Control and Prevention (CDC), typical symptoms of the flu include fever, cough, sore throat, muscle aches, headache, runny or stuffy nose, malaise, and occasional vomiting or diarrhea.

Symptoms of the flu usually come on suddenly, and most people infected with the flu virus recover within two weeks. But for a small percentage of people, the flu virus can cause other complications, such as pneumonia.

In the United States, the 2019-2020 flu season has caused 22 million ~ 31 million infections and 12,000 ~ 30,000 deaths.

As a result, the fatality rate of this influenza outbreak in the United States is less than 0.1%. In addition, so far, about 1% of infected people in this flu season have required hospitalization for the degree of symptoms, which is similar to the previous flu season.

It should be pointed out that the data on influenza infections and deaths in the United States are not obtained through direct statistics, but are based on the evaluation results of the dynamic model established by the CDC in the United States.

The model is based on the number of infections, hospitalizations, vaccination rates, high-risk cases, and deaths in 9% of the population covered by 13 influenza surveillance sites across the United States.

The reason for this is that, on the one hand, a large number of people with influenza may not go to the hospital or have not been tested for influenza virus, and on the other hand, some people may die from complications caused by influenza (e.g., pneumonia, cardiovascular disease, etc.), for whom the direct cause of death is not influenza, but influenza is the cause of death.

It can be seen that the CDC's statistics on flu deaths are also broader, which partly explains the tens of thousands of flu deaths in the United States every year.

For 2019-

The symptoms and severity of CoV infection, people are trying to get to the bottom of it.

In the latest study, the research team pointed out that the most common symptoms of COVID-19 are fever and cough, and digestive symptoms such as diarrhea and vomiting are extremely rare.

A previous study published in The Lancet also showed that only about 5% of patients showed symptoms of sore throat and runny nose.

In contrast, COVID-19 is much more severe than the flu. According to data released by the World Health Organization (WHO) on February 4, about 14% of the more than 20,000 patients reported were critically ill.

For 2019-

The fatality rate of CoV infection, we do not have exact data at the moment.

Based on the judgment of existing research, 2019-

The fatality rate of CoV infection is about 1%~3%, which is much higher than that of influenza.

However, this number is subject to change as the pandemic progresses.

U.S. Secretary of Health and Human Services Alex Aza

At a press conference on Jan. 28, it said there could have been a "severe skew" in the initial cases detected in the early days of the outbreak.

That is, the initial confirmed cases are likely to be mostly more severe patients, which may result in a higher calculated mortality rate than actually is.

As more people with mild symptoms are diagnosed, the mortality rate is likely to decline, Azza said.