Delta Variant symptoms

Symptoms of Delta strains, headaches, runny nose, etc. = British research Coronavirus

The Delta strain of the new coronavirus, which is spreading in the United Kingdom, has revealed an increasing number of patients complaining of symptoms such as headache, sore throat, and runny nose.

According to Professor Tim Spector, who runs the Zoe Covid Symptom study , which studies the symptoms of COVID-19, young people infected with the Delta strain may feel like they have a “severe cold.”

However, even if the symptoms are not so strong, there is a risk of infecting others.

According to the United Kingdom National Health Service (NHS), the typical symptoms of the new virus are:

  • Long-lasting cough
  • Fever
  • Abnormal sense of smell and taste

But Specter says that the number of people complaining of these symptoms is now declining, according to data from thousands of people who entered the symptoms from the Zoe app.

“Since the beginning of May, we’ve seen the most common symptoms that app users complain about, but it’s different.”

The change seems to be related to the epidemic of delta strains identified in India. Delta strains currently account for 90% of infected people in the United Kingdom.

Fever is still a common symptom. On the other hand, abnormalities in the sense of smell and taste fell below the 10th place, Professor Specter said.

“This mutant seems to have different symptoms. I might go to a party thinking I had a seasonal cold and spread the virus to the other six people there.”

“I think this has a lot to do with the problem right now.”

“If you’re young, your symptoms are often relatively mild. You might think it’s just a bad cold or something’sick’, but please refrain from going out. I want you to receive it. “

“Muscle pain”

The COVID-19 study ” React ” by Imperial College London also shows that the infection has a variety of symptoms. The study was conducted on more than one million people when the alpha strains identified in the United Kingdom were rampant.

In addition to the typical symptoms, chills, loss of appetite, headache, and muscle aches were common.

React explains that these symptoms “may have other causes and are not the only reason to be tested.”

“If you have any questions about your symptoms, get medical advice.”

What is a mutant strain?

In all organisms, not just viruses, some misreading or recombination may occur in the process of copying genes, and some genetic information may change. This is called ” mutation “ “.

In this, there may be offspring with new qualities. This offspring is called a ” mutant strain “. It is called without changing the name of the virus because it is just a variation of the same virus with different properties. (By the way, it is wrong to say that the mutant “species” is a completely new organism. The Japanese Society for Infectious Diseases also warns.

The new coronavirus mutant strains are named in the Greek alphabet “α (alpha), β (beta), γ (gamma), Δ (delta) …”. Let’s take a look at the characteristics of the Delta strain, which is particularly prevalent in Japan among the many mutant strains. (As of August 2021)

What is the infectivity and transmission route of Delta strains?

Delta strains that have spread from India have spread all over the world, and on May 11, 2021, WHO positioned them as “mutations to watch”.

In Japan as well, the replacement with Delta stocks is progressing. According to an analysis by the National Institute of Infectious Diseases Infectious Disease Epidemiology Center (as of July 27, 2021), the proportion of positive individuals with delta strain mutations is estimated to be 75% in the Kanto region and 32% in the Kansai region. I am. ( According to the 45th Ministry of Health, Labor and Welfare New Coronavirus Infectious Disease Control Advisory Board Material )

Furthermore, it was announced in Fukushima Prefecture that it was 88.9-100% (until October 2021), and it can be said that the replacement of Delta stocks is progressing.

According to a report from the CDC (Centers for Disease Control and Prevention), it has been confirmed that it is more than twice as contagious as the conventional new corona . Comparing the Delta strain with other infectious diseases, it is more infectious than seasonal influenza and general “cold”, and may be at the same level as airborne chickenpox, so it can be said that further infection control is necessary. Probably.

In 2021, the main transmission routes of Delta strains are considered to be contact transmission and droplet infection. It has been suggested that the particle size is smaller than other viral infections as the reason why it is more infectious than influenza and colds.

The CDC report does not clearly suggest an airborne infection as of October 2021. We will update it as new information becomes available.)

What is the incubation period for Delta strains?

A Chinese study believes that the time it takes for the Delta strain to detect the virus is about two days shorter than the conventional Coronavirus.

Since the incubation period of the conventional new coronavirus is 5 days, it will become positive in about 3 days . As a background, it has been shown that the amount of virus in the infected person’s body is more than 1000 times higher than that of the conventional coronavirus .

Another pre-reviewed study suggests that the virus may be shed for a longer period of time, leading to higher infectivity.

Are Delta strains prone to severe illness?

The bottom line is that Delta strains are more likely to be ill .

In a Canadian study , hospitalization risk, ICU admission risk, and mortality risk were increased by 108% and 133%, respectively, compared to the traditional coronavirus.

In addition, in a clinical study of 43,338 patients in the United Kingdom, the risk of emergency outpatient visits and hospitalization was increased compared to the alpha mutant strain (emergency outpatient visits within 14 days: 1.45 times, hospitalization within 14 days: 2.26 times). It is suggested that.

From this, it can be said that the Delta strain has an even higher risk of becoming more severe than the mutant strain Alpha strain.

What is the effect of the vaccine on Delta strains?

The question then is, “Is the Delta strain also effective as a vaccine?”

According to the CDC’s announcement , “Infection prevention effects have remained at 64-87% in each study, and vaccines, including Delta strains, are extremely effective.”

The above results are the results of using a Pfizer vaccine, but the effect of the vaccine in each study was ” 64-87% for infection prevention and 93-100% for aggravation “. It can be said that the preventive effect is higher than that of influenza vaccines.


  • The effect of the vaccine is slightly lower than that of the conventional strain.
  • The strength of infectivity and the susceptibility to becoming severe are stronger than those of conventional strains.

Therefore, it can be said that further infection control measures are needed. The CDC also encourages thorough infection control measures, including masks. It is important to be prepared to “keep the virus out of your body” without overconfidence that “it’s okay if you get the vaccine”.

About “subspecies” of Delta strain

Also, from June 21st in Japan, variants of the Delta strain have appeared, including the “Delta Plus strain”  which is a further mutation of the Delta strain.

Although I will omit the technical explanation, the “subspecies” of the Delta strain is a new mutation added to the “spike protein” that invades the human body.

However, for now, just because it is a variant of the “Delta strain” does not mean that the existing vaccine will not work, but it is thought that the effect of the “mutation” is smaller than before.

About the new coronavirus mutant strain “Omicron strain “

From November 28, 2021, the “Omicron strain” that developed from South Africa appeared as a new mutant strain, and community-acquired infections are occurring in Japan as well. Please refer to the following for the Omicron strains.

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