January 23, 2022

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First epidemiological study of persons infected with Omicron was published

The first epidemiological study of persons infected with Omicron was published



 

The first epidemiological study of persons infected with Omicron was published, revealing the severity of the disease in the real world

The new coronavirus Omicron mutant strain is setting off a new round of COVID-19 epidemic around the world.

Epidemiological research is the basis for revealing the infectivity, immune escape and severity of the Omicron mutant strain, and it is also the key to prevention and vaccination deployment.

 

Danish scholars published the epidemiological characteristics of 785 cases of Omicron infections in Denmark in Euro Surveill , and compared them with those infected with the Delta mutant strain in the same period, providing very important information. Let’s make an interpretation.

 

Denmark first discovered two Omicron infected persons among travelers returning from South Africa on November 28, 2021. As of December 9, a total of 785 infected persons have been registered.

 

It should be noted that the article reports on Omicron variant cases, not patients; we have translated cases into infected persons here.

It is necessary to first distinguish whether the research object is a patient or an infected person in order to make a scientific and objective understanding later, especially when comparing with previous knowledge.

 

The cases reported in Denmark are national testing data, not hospital data. That is to say, the cases are defined as Omicron infected persons confirmed by RT-PCR or whole genome sequencing (WGS).

It needs to be mentioned in particular that Denmark is also in a leading position in the world in the detection of COVID-19s.

The scope of detection is not only clinically confirmed cases, but also close contacts of confirmed cases, as well as all international travelers from December 1st. Detection.

 

Therefore, this Danish epidemiological study shows the relatively complete situation of Omicron infected persons; this is exactly the data that researchers from various countries urgently need to know.

 

A Danish study shows that the number of Omicron cases in the country has increased by 40% every day since December 4. This means doubling in less than two days.

 

The first epidemiological study of persons infected with Omicron was published.

 

1. Demographic characteristics of infected persons

The age of the infected persons ranged from 2 to 95 years, with a median age of 32 years; 55% were men; 77% had no travel history, indicating that this group of studies is closer to community infection cases.

 

2. History of vaccination and previous history of new coronavirus infections of persons infected with Omicron

In this group of Omicron infected persons, a total of 83.1% were fully vaccinated or booster vaccinated, of which 76% received two doses of vaccine, and another 7.1% received a third dose of vaccine.

Another 4.3% had previously been infected with the new coronavirus. Among those infected with Delta, only 53.2% were fully vaccinated or boosted vaccinated.

Only 0.9% had previously been infected with the new coronavirus.

 

3. The condition of people infected with Omicron

It can be seen that 73% of Omicron infected persons who reported symptoms have symptoms and 27% are asymptomatic.

Among those infected with Omicron, 1.2% were hospitalized, compared with 1.5% of those infected with Delta; among those infected with Omicron, 0.13% lived in the ICU, compared with 0.11% of those infected with Delta; among those infected with Omicron, no cases died, compared with those infected with Delta. It is 0.07%.

 

 

 


Expert interpretation:

This is the first epidemiological study on the Omicron mutant strain. Although the sample size is small, the test done in Denmark is very complete, so it still provides very critical information.

 

This set of information also continues to verify:

1. The Omicron mutant strain has higher immune escape than the Delta mutant strain

83.1% of Omicron-infected people have received 2 or more doses of vaccine in the past. However, this set of data also allows us to see for the first time that 50% of people infected with the original Delta mutant strain have also received more than two doses of vaccine. In Denmark, 77.5% of the population has been fully vaccinated, and it has still failed to stop the spread of the new coronavirus Omicron mutant strain.

 

2. Omicron is extremely contagious

As shown in this article and the image above, once Omicron spreads, it doubles in less than 2 days.

 

3. 1.2% of Omicron infected people are hospitalized, and 0.13% need to be admitted to the ICU

So the symptoms of Omicron infected people in the real world are really not serious. But is it weaker than the previous strain?

Only 1.5% of Delta-infected patients are hospitalized, and 0.11% need to be admitted to the ICU. This article did not make a statistical comparison.

We suspect that the author is worried that the conclusion is unreliable considering the small sample size.

 

However, this result has shown that the severity of the disease in this group of patients infected with the Omicron mutant strain is similar to that of those infected with the Delta mutant strain; but don’t forget that the Omicron group has a higher proportion of vaccinators and previous infections. In fact, vaccination makes the condition of COVID-19 patients in the real world generally lighter.

 

4. Do we have a reason to relax?

Seeing this result, I am definitely more daring to go out for Christmas with my family. But the conditions are: complete vaccination or vaccination with booster shots; in addition, strictly wear a mask and keep a distance.

But the government and public health managers are more anxious and nervous.

Because the number of infection cases increases, it means that the total number of hospitalizations and deaths in the whole society will increase.

 

More importantly, according to a case report from another Norwegian study, the common symptoms of Omicron infected people after vaccination are completely different.

The most common symptoms are: cough (83%), runny nose (78%), fatigue ( 74%), sore throat (72%) and headache (68%). You see, is it different from the flu?

 

(Vaccinators) Omicron mutant strains with little difference between early symptoms and influenza will undoubtedly reduce the intent of the infected person to see a doctor and the difficulty of epidemic prevention.

However, are Omicron infected persons similar to influenza due to the Omicron mutant strain? The answer from the Norwegian study is “no”.

At present, there is no difference in the symptoms of people infected with the Delta mutant strain of Omicron infected people in Norway, all of which are due to vaccination, which reduces the severity of the disease.

 

 

 

 


Brief summary:

1. The Omicron mutant strain is extremely contagious. Once it spreads, the case doubles in two days. Therefore, the first time diagnosis and isolation is very important.

 

2. The immune escape of the Omicron mutant strain to the vaccine is very obvious, but the Delta mutant strain is also more active. Because after the vaccination time is prolonged, the protection is reduced. Therefore, it is very important to strengthen vaccination.

 

3. The good news is that in the real world, the symptoms of Omicron-infected patients are indeed milder than before (1.2% are hospitalized, 0.13% are admitted to the ICU), but there is currently no evidence that they are milder than Delta mutant infections (1.5% hospitalized, 0.11% Enter ICU). The symptoms of the current infected people have become milder, mainly because most of the infected people are fully vaccinated.

 

4. The bad news is that the early symptoms of Omicron infected people are very similar to flu, which will also increase the difficulty of epidemic prevention.

 

Therefore, the odds of people infected with Omicron are significantly higher; but the symptoms of Omicron infection in fully vaccinated people are relatively not as terrible as before, but they are probably still similar to those infected with Delta.

Scientists hope that the first epidemiological study of Omicron infected persons will help you understand the current epidemic situation accurately.

 

 

 

 

 

Reference:

1. https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2021.26.50.2101146#html_fulltext

The first epidemiological study of persons infected with Omicron was published.

(source:internet, reference only)


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