Variant of Corona Virus: How many variants of Covid-19 are there today?

2021-08-08 06:12 PM

The World Health Organization (WHO) warns that the Delta and Delta Plus mutations are threatening the epidemic control efforts of many countries around the world.

The SARS-CoV-2 virus continuously mutates to create new variants with a terrifying rate of spread, causing the number of cases and deaths to increase rapidly. So how many strains of Coronavirus are there today? Which variant of Coronavirus is the most dangerous?

What is Corona Virus?

Coronaviruses are a large family of viruses that include many strains of viruses that affect the respiratory system of mammals, including humans. It is a disease that affects the respiratory system with mild to severe symptoms such as the common cold, fatigue, pneumonia, severe respiratory failure, affecting the digestive tract or other parts of the body. , causing the patient to die.

2019-nCoV is a new strain of Coronavirus that has never been detected in humans before. This virus was identified as the causative agent of the acute respiratory infection COVID-19 in an investigation that originated in a large seafood and animal market in Wuhan, Hubei province, China at the end of the year. 2019. Before that, coronavirus strains have also caused many dangerous and life-threatening pandemics such as Severe Acute Respiratory Syndrome (SARS-CoV) 2002 or Middle East Respiratory Syndrome (MERS – 2019). CoV) in 2012.

What is Coronavirus mutation?

Coronavirus variant is the “term” to describe a variant of a Coronavirus that is significantly different from its congeners. This difference is reflected in the aspects: transmissibility (ability to transmit disease), virulence (ability to cause disease), susceptibility to therapeutic/preventive vaccines (tolerance) of the SARS-CoV-2 virus.

Is virus variation normal or not? How do they vary?

Coronavirus has 4 groups (group A, B, C, D), group B has the ability the most mutation. In the past, Coronavirus can cause colds, popularly known as the flu, many people think that this disease is like the flu, but in fact, it has a different cause and has a high mutation rate. In 2002, Coronavirus mutated into the virus that caused the SARS pandemic with a high mortality rate, ranging from 40-60%. At that time, Vietnam was the first country to control this disease.

By 2019, Corona continues to mutate into nCoV, it binds to 85% of the classic corona genes, 15% mutates into a new strain. The first cases were first recorded in Wuhan, then spread throughout, and became a global pandemic. During transmission between countries, continents, and between people, the virus continues to mutate, which is the difference between SARS-CoV-2. Experts confirm that it is completely normal for the virus to continuously mutate.

We can understand that changes in the nature of the genome are called "variants". After transforming, they will have clear, specific manifestations called "mutants". That is when the virus has changed in the genome and has become a new strain that is different from the original strain - that is the mutation of the virus.

Viruses only replicate completely within the living cell of the host (bacteria, plant, or animal). The structure of the virus consists of an outer shell of proteins or sometimes lipids (alcohol, antibacterial soaps are to remove this shell), a core of RNA or DNA, and sometimes enzymes necessary for the first step. virus replication.

During the replication process, the viral genome will have changes, especially those with an RNA genome. The SARS-CoV-2 virus has an RNA genome and it also has changed due to mistakes in the replication process. The changes are largely insignificant without altering the virus' genetic code, but at least one altered genetic code qualifies as a variant.

However, there are variants that make the virus more difficult to spread or even die prematurely because it cannot escape the host cell. It should be noted that the variants that help the virus penetrate and spread faster are the ones that will survive and gradually replace the original virus strains. In the past time, the world has witnessed SARS-CoV-2 virus variants raging, most notably the Delta variant, which first appeared in India in October 2020, spreading to more than 100 countries. countries and territories.

Explaining the reason why the SARS-CoV-2 virus spreads so quickly, epidemiologists say, thanks to the spike proteins on the surface that help the virus stick to the respiratory tract. After attaching, it will jump to epithelial cells and replicate, then break out of old cells to enter new cells and infect the community through the nose and mouth. If genetic modification makes these spike protein "tentacles" more tightly attracted, it inevitably leads to faster infection.

What are the latest strains of Coronavirus today?

Currently, the World Health Organization (WHO) divides the variants of SARS-CoV-2 into 2 groups: Variants of interest (VOIs) ) and Variants of Concern (VOCs).

Variants of interest (VOIs): when there is a change in the phenotype or there is a gene with multiple mutations capable of altering amino acids related to the phenotype; and cause community transmission or multiple cases/clusters of cases occurring at the same time; or found in many countries.
Variants of concern (VOCs): are those that have been confirmed to be associated with a significantly increased likelihood of transmission; significantly change the Covid-19 epidemiological situation in a negative way; increased virulence/aggravation of clinical manifestations; effective reduction of public health measures; or reduce the effectiveness of current vaccines, diagnostic tests, and therapies.
Currently, there are four variants of the SARS-CoV-2 virus classified by WHO as a concern, including Alpha, Beta, Gamma, and Delta, which were first detected in the UK, South Africa, Brazil, and India. In particular, the Delta variant is considered the most dangerous, the dominant infectious strain globally because of its high ability to spread. Previously, the old way of naming variables was often combining "variant" + "country name" which was not used because it could create stigma. (first)

1. British Coronavirus variant (B.1.1.7 Series – aka variant 20B/501Y.V1)

Variant B.1.1.7, also known as Alpha, was first discovered in the United Kingdom, becoming a very common virus strain in the city of London and southeastern England. This is also the mutation marking the new global outbreak of Covid-19 at the end of 2020. To date, more than 100 countries have had people infected with the B.1.1.7 variant, including Vietnam.

According to the Public Health Agency (PHE) data, the first person infected with this mutated virus was detected on September 20, 2020. By mid-November, the strain was infecting more than 20-30% of cases in London and parts of the city's east. 3 weeks later, about 60% of new patients are infected with this mutated virus. On December 23, British scientists announced to the world about a completely new strain of SARS-CoV-2.

The Alpha variant contained 23 genetic mutations, particularly those that were not genetically related to the strain of the virus that was infecting Britain at the time. According to Chris Whitty, England's Chief Medical Officer, this number is unusually high.

Health officials in the UK have warned that the B.1.1.7 variant of SARS-CoV-2 is up to 70% more transmissible than the old strain. In the weekly epidemiological update, WHO also warned that the B.1.1.7 variant showed a strong ability to infect the virus. In the UK, testing samples for the new strain of SARS-CoV-2 increased from 63% in the week from December 14, 2020, to 90% in the week from January 18, 2021.

Variant B.1.1.7 quickly became the most common virus strain in cases globally. This is also the strain found in many cases of the current outbreak and in Hai Duong in July 2020.

At the end of April, according to information from the Ministry of Health, the results of the Pasteur Institute in Ho Chi Minh City, sequencing the genes of imported cases from Cambodia to Vietnam, showed that 85.7% of samples were infected with B.1.1. detected in the UK), the remaining 14.3% carry the variant B.1.351 (discovered in South Africa).

How is variant B.1.1.7 different?

Variant B.1.1.7 has a mutation in the receptor-binding region (RBD) of the spike protein at position 501, where the amino acid asparagine (N) has been replaced by tyrosine (Y), so it is abbreviated as N501Y. This variant also has several other mutations, including:

69/70 fragment: This double break occurs spontaneously many times and can lead to conformational changes of the spike protein.
P681H: near the S1/S2 furin cleavage site, a site of high variability in coronaviruses. This mutation has also appeared spontaneously several times.
ORF8 stop code (Q27stop): mutation at position ORF8.
The strain B.1.1.7 has high infectivity, the viral load increases 4 times compared to the previous strain. In previous outbreaks, epidemiologists calculated an infection cycle of about 4-5 days with a very clear transmission cycle, but this time the cycle is shorter with the onset of the disease also very fast. In this variant of Coronavirus, it was only on the 2nd day that a virus appeared in the oropharynx, from there, the ability of the virus to multiply, eliminate pathogens, and spread in the air was very high. The new variant virus strain found in the UK has about 20 mutations, many of which affect how the virus enters human cells and spreads disease.

2. South African variant (B.1.351 Series, aka 20C/501Y.V2)

In December 2020, the South African Ministry of Health announced for the first time a new mutant strain called Belta (B.1.351) was discovered in Nelson Mandela Bay, South Africa. From the summer to October 2020, the country had only about 2,000 infections on average per day. However, this number has increased significantly since mid-November 2020 with more than 16,000 new infections per day, more than the peak of the epidemic in 2019. At that time, the South African Ministry of Health said, this variant accounted for from 80-90% of new infections are in the country and contribute to the increase in infections and hospitalizations across South Africa.

According to Professor of Epidemiology Salim Abdool Karim, co-chair of the scientific council at the South African Ministry of Health, the new virus variant is 50% more transmissible than the old strain. "We've never seen a virus spread so quickly," said epidemiologist Tulio de Oliveira, head of the Krisp laboratory in South Africa.

According to scientists, the Belta variant in South Africa is different from the Alpha variant in the UK, 1.5 times more infectious, more aggressive, able to evolve and adapt more... January 31 In 2021, Vietnam recorded the first case of the South African Belta variant (B.1.351) from a South African immigration specialist.

How is variant B.1.351 different?

Variant B.1.351 has many mutations occurring in the spike protein, including N501Y. Unlike the B.1.1.7 strain discovered in the UK, this variant does not have a 69/70 break.
The Belta variant (501.V2 or B.1.351) carries three mutations (E484K, K417N, and N501Y) in important regions of the gene. This is where the spike protein the virus uses to attach to human cells. In particular, E484K has the ability to reduce the recognition of human antibodies to the virus. As a result, it is easier for nCoV to overcome the immune barrier generated by the COVID-19 vaccine.

3. Brazilian variant (P.1 Series)

The Gamma variant, also known as the P.1 strain, was first detected by the National Institute of Infectious Diseases (NIID) in a group of four people in Japan in January 2021, although it has existed in Brazil. from November 2020. According to the New York Times, these are tourists who contracted the new variant after arriving in the state of Amazonas, Brazil.

After that, the P.1 variant quickly became the dominant virus throughout Brazil and spread terror to other countries around the world. Studies show that the P.1 variant has a "unique mutation constellation" and very quickly became a dominant variant with a rapid spread rate, able to re-infect people who had previously been infected. cured. At the same time, the scientists also calculated that the P.1 virus is 2.5 times more infectious than the original SARS-CoV-2 virus strain that appeared initially, the ability to resist antibodies is also higher. .

How is the P.1 variant different?

Variant P.1 has 17 unique amino acid mutations and 4 substitution mutations, of which the three most worrisome are K417T, E484K, and N501Y. In particular, E484K attracted the greatest attention and it was also found in the South African strain B.1.351. The E484K mutation is thought to cause P.1 to re-infect even those who have recovered from the disease.
E484K appears on the protein spike of the virus, causing the P.1 variant to change shape, avoiding detection by antibodies produced after vaccination against COVID-19, or after the patient first contracted COVID-19 due to other pathogens. other virus strains.
In addition, mutations N501Y and K417T are the agents that cause the P.1 strain to spread more strongly than other virus strains. According to the New York Times, research results in the city of Manaus show that P.1 has the ability to spread more strongly than old virus strains by 40-120%.

4. Indian dual variant (Delta or B.1.617.2)

Delta variant (B.1.617.2), also known as "double mutation" was first discovered in India in December 2020. With the ability to infect dangerously, Delta soon became the dominant virus strain in India, to the United Kingdom, and in turn "visiting" other countries, overwhelming the global health system.

With its contagious and difficult-to-trace characteristics, according to WHO statistics, this variant has spread to 124 countries and territories. The new data show that the Delta variant is highly contagious mainly because people infected with this variant carry a viral load in the nasal cavity 1,000 times greater than people infected with previous SARS-CoV-2 virus strains.

The European Center for Disease Prevention and Control (ECDC) says Delta is 40 to 60 percent more infectious than the Alpha variant first detected in the UK. The ECDC predicts that by the beginning of August, up to 70% of new cases in the EU will be infected with Delta variant and this number will increase to 90% by the end of August.

"The Delta variant is more intense and contagious than previous viral strains," said Rochelle Walensky, Director of the US CDC. This is one of the most contagious respiratory viruses that we know of and that I have seen in my 20-year career."

Hospitalization rates for patients infected with the Delta variant were also 85% higher than with the Alpha variant. There is currently no evidence that people infected with the Delta variant are sicker or more likely to die. However, studies from Scotland published in The Lancet indicate that the Delta variant can make patients more likely to be hospitalized than previous variants. Increasing the likelihood of hospitalization can lead to an increased risk of death, especially for patients with underlying medical conditions such as diabetes, obesity, cardiovascular disease, etc.

Not only that, epidemiologists are concerned that the Delta variant that is "storming" cannot be stopped, the new Delta Plus variant - considered a "descendant" of Delta is equally dangerous, very easy. spread, they bind strongly to lung cell receptors and are resistant to monoclonal antibody therapy.

How is the Delta variant different?

Variant B.1.617 is called "double mutant" because it contains two mutations that appear in other dangerous virus strains, L452R, which appeared in the variant in California (USA), and E484Q, similar to the one that appeared in Vietnam. South Africa and Brazil. In addition to the above 2 mutations, B.1.617 has about 11 other mutations. It is these mutations that help the virus evade natural immunity as well as make it more resistant to vaccines and antibody treatments. This feature has created the second "tsunami" of the COVID-19 epidemic in India.

Epidemiologists say that the Delta variant is a particularly formidable foe. If the mutation continues, this strain will pose a huge threat, which is why medical professionals are extremely stressed. With its high infectivity, the Delta variant has the potential to reverse even the impressive anti-epidemic achievements in countries with rapid vaccination rates such as the US and Europe.