Medical Biotechnology | Decoding the new coronavirus mutation: What is the "variant of concern"? How to prevent the Omicron variant? All the key points are here!

The novel coronavirus has been raging around the world for nearly three years. According to incomplete statistics, the cumulative number of confirmed novel coronavirus cases worldwide has exceeded 580 million, and the cumulative number of deaths has exceeded 6.4 million, causing huge losses to people's lives and property. The continued spread and rebound of the novel coronavirus epidemic is mainly due to the continuous mutation of the virus. Therefore, it is particularly necessary to understand the mutation and main variants of the novel coronavirus and be familiar with prevention and control measures.

Coronavirus mutations

Relevant research shows that more than thousands of new coronavirus mutants have been discovered worldwide, and the mutations are mainly point mutations, that is, one or several nucleotides in the viral gene DNA change, causing the amino acids they encode to change, resulting in certain characteristics of the virus (such as infectivity, pathogenicity, etc.) Changes.

In order to avoid stigmatizing and discriminatory names of the new coronavirus variants, and also for ease of use and memorization, on May 31, 2021, the World Health Organization (WHO) announced the use of Greek letters to name the new coronavirus variants. According to statistics, more than 10 new coronavirus variants have been named by the WHO, namely: Alpha, Beta, Gamma, Delta, Omicron, Lambda, μ, Epsilon, Eta, Lota, Kappa, Zeta, and Theta.

Novel coronavirus "variants of concern" and their classification

The "variants of concern" of the new coronavirus refer to the variants discovered during monitoring that may cause increased transmissibility, increased virulence, changes in disease severity, or affect existing prevention and control measures such as diagnostics, therapeutic drugs and vaccines.

The following 10 aspects are used to determine the degree of concern of virus variants:

(1) Whether the infectiousness increases;

(2) whether the incidence rate has increased;

(3) whether the case fatality rate increases;

(4) whether the diagnostic rate is reduced;

(5) Whether the sensitivity to existing antiviral drugs is reduced;

(6) Whether the sensitivity of neutralizing antibodies is reduced;

(7) Whether it is easy to evade the body's immunity;

(8) Whether it is easy to be infected again;

(9) whether there is an increase in infections among vaccinated individuals;

(10) Whether the infection rate increases in special regions and special populations (such as children and people with immunodeficiency).

Referring to the above standards and based on the risk level of virus variants, WHO divides the "variants of concern" of the new coronavirus into four categories: variants of high concern (VOHC: Variant Of High Concern); variants of concern (VOC: Variant Of Concern); variants of interest (VOI: Variant Of Interest); and variants that require further observation/monitoring (VUI/VUM: Variant Under Investigation/monitoring).

Through the evaluation of the detected variants, WHO classified the new coronavirus variants into three categories: VUI/VUM, VOI and VOC. There is currently no VOHC. The general principle of classification is: if the variant shows any of the above 10 points, it is called VUI/VUM or VOI; if it spreads beyond a limited range, it is classified as VOC; if the effect of the variant on effective intervention or prevention is significantly reduced, it belongs to VOHC. Of course, whether the virus's infectiousness is enhanced, whether the morbidity and mortality rates are enhanced, and whether the protection rate of vaccinated individuals and the sensitivity to neutralizing antibodies are reduced are all key factors in measuring the attention of virus variants.

Five "variants of concern" (VOC) named by the WHO Currently, more than 10 new coronavirus variants have been named by the WHO, and five of them are listed as "variants of concern":

Alpha, Beta, Gamma, Delta and Omicron.

1

The Alpha variant, also known as the B.1.1.7 lineage (English: Lineage B.1.1.7), was first discovered in the UK in September 2020. Because it has several key mutation points, N501Y, P681H and H69-V70del, this virus variant has very strong transmissibility and infection ability, and is more lethal and spreads faster than the common new coronavirus.

2

The Beta variant, also known as the B.1.351 lineage (English: Lineage B.1.351), was first discovered in the Nelson Mandela Bay metropolitan area in the Eastern Cape Province of South Africa in October 2020. Due to the E484K mutation on its spike protein, its ability to attack the human body in a short period of time is 3-5 times that of the ordinary new coronavirus, making it a highly lethal and fast-spreading new coronavirus variant.

3

The Gamma variant, also known as Lineage P.1, was first discovered in Tokyo, Japan on January 6, 2021. It has three special mutations: N501Y, E484K, and K417T. Therefore, this virus variant spreads quickly, has strong killing ability, and is highly drug-resistant. Currently, there is no good treatment for this virus variant.

4

The Delta variant, also known as the B.1.617.2 lineage (English: Lineage B.1.617.2), was first discovered in India at the end of 2020. This virus variant has higher transmissibility, pathogenicity and immune escape capabilities. It spread to more than 100 countries around the world in a very short period of time and became the dominant virus variant of the global COVID-19 pandemic in 2021.

5

The Omicron variant, also known as the B.1.1.529 lineage (English: Lineage B.1.1.529), was first discovered in the Republic of Botswana in southern Africa on November 9, 2021. It is the most contagious and vaccine-resistant variant of the new coronavirus with the most mutation points to date, and is estimated to reduce the effectiveness of current vaccines by 40%.

Omicron is wreaking havoc around the world

About Omicron

The COVID-19 pandemic has entered its third year, and the Omicron variant has replaced the Delta variant as the dominant virus strain that influences the global COVID-19 pandemic. It is the most mutated, most mutated, and most contagious variant to date. More than 10 subtypes of Omicron have been discovered in the world, including BA.1, BA.2, BA.3, BA.4, BA.5, etc. The WHO said that the dominant variants in the current global epidemic are BA.4 and BA.5.

Epidemic characteristics of Omicron variants

1

More mutations Omicron is considered the "most dangerous strain" because 32 mutations were found on its spike protein (the global Delta has only 16), which is an "unprecedented" number of mutations. In particular, Omicron has at least 10 mutations in the receptor binding region (RBD) (Delta has 2 and Beta has 3).

2

Studies have found that K417N, G446S, E484A and Q493R mutations on the Omicron spike protein are involved in immune escape. These mutations enhance the affinity between the virus and the human cell receptor ACE2, thereby competitively inhibiting the binding of neutralizing antibodies to the spike protein (S), allowing the virus to escape immune escape and avoid detection and attack by the immune system.

3

Stronger transmission Research shows that compared with Delta, Omicron BA.1 spreads 77% faster. BA.2, which is prevalent in my country, spreads 66% faster than BA.1. It was also found that compared with the transmission of the original strain (R0=3), the transmission of Delta (R0=7) increased by 2-3 times. In Omicron, the transmission (R0=10) was further enhanced, which is 1.4 times that of Delta and 3.3 times that of the original strain.

4

Symptoms last shorter Although the new coronavirus has produced many variants through mutation, the symptoms caused by infection are basically similar. Clinical data show that patients infected with Omicron have shorter clinical symptoms and recover faster. According to statistics, the average duration of clinical symptoms of patients infected with Delta is about 8.9 days (vaccinated people) and 9.6 days (unvaccinated people), while the duration of symptoms of patients infected with Omicron is significantly shorter, at 6.9 days (vaccinated people) and 8.3 days (unvaccinated people).

5

The study found that the novel coronavirus has been around for more than two years, and the virus has undergone multiple mutations, with its ability to spread increasing, but its ability to kill the host decreasing. From the current cases of infection with Omicron worldwide, most are mild cases, and the severe infection rate and mortality rate have decreased.

It is worth noting that although Omicron may not have as high a severity and mortality rate as other variants, it is still a deadly virus. As Dr. Tedros Adhanom Ghebreyesus, Director-General of the WHO, said at a press conference, "While Omicron does appear to be less severe than Delta, especially in those who have been vaccinated, this does not mean that it should be classified as mild."

Accelerate vaccination and build immune barriers

Related studies have shown that although the multiple mutations of the Omicron variant increase the risk of immune escape, it has not completely escaped the existing vaccines. Completing the full course of vaccination can still effectively reduce the risk of hospitalization, severe illness and death caused by the Omicron variant. Therefore, the existing vaccines still have a certain protective effect against the Omicron variant, and active vaccination is still the most effective preventive measure.

Adhere to the general strategy of "preventing imports from outside and rebound from within" and the general policy of "dynamic zeroing"

At present, the global COVID-19 epidemic is still at a high level, and South Korea and Vietnam, which are neighboring my country, have also become the countries with the largest number of newly reported cases per day in the world. In addition, the emergence of Omicron BA.5, which is more infectious and has become the main global epidemic strain, has increased the pressure on my country to "prevent imported cases from abroad". In addition, the local epidemic caused by the Omicron variant has also spread to many provinces and cities in my country. The national epidemic has shown the characteristics of multiple points, wide areas, and frequent outbreaks, and the epidemic situation is severe.

Therefore, in order to effectively prevent a large-scale outbreak of the epidemic, minimize the spread and mortality rate, and avoid the loss of more lives, our country must always adhere to the general strategy of "preventing imported cases from outside and rebound from inside", and continue to adhere to the general policy of "dynamic zeroing" without wavering or relaxing.

Increase the intensity of nucleic acid testing and strengthen the management of regular nucleic acid testing

Nucleic acid testing is a key means to quickly discover the source of infection, lock in control targets, and then take isolation and other measures to cut off the transmission routes. It has played an important role in my country's successful handling of clustered epidemics.

At present, my country's epidemic prevention and control has entered a new stage of responding to the epidemic of the Omicron variant. The Omicron variant has the characteristics of faster transmission, shorter incubation period, and stronger concealment. These characteristics make it difficult for some early infected people to be discovered, causing the virus to spread rapidly in a short period of time. In this case, we must fight fast with fast, conduct nucleic acid testing as soon as possible, screen out positive infected people and take effective control measures, cut off the virus transmission chain in a timely and effective manner, and achieve the greatest prevention and control effect with the lowest cost. Therefore, it is very necessary to continue to carry out multiple rounds of nucleic acid testing in areas where the epidemic has occurred and to carry out normalized nucleic acid testing in areas where the epidemic has not occurred.

Take good personal protection and keep in mind the "four major measures" and "eight points of attention"

"Four major measures": wear masks, wash hands frequently, ventilate frequently, and gather less.

"Eight Points of Attention": First, reduce the flow of people and reduce crowds; second, do not go abroad, do not gather in groups, and do not go to medium and high-risk areas; third, go out at off-peak times and maintain a distance of 1 meter; fourth, visit relatives and friends less often, do not hug or shake hands; fifth, reduce family gatherings, and advocate separate meals and public chopsticks; sixth, choose popular attractions with caution, and it is better to buy tickets online; seventh, patients with fever are very critical, and they should be seen in special outpatient clinics; eighth, reduce visits to neighbors, and report risk personnel early.

Author: Yaohuluwa Medical and Biological Science Popularization Group