Why does the "Omicron" variant make the world nervous?

Expert in this article: Yang Jing, PhD in Immunology, author of popular science on vaccines (viral vaccine development, vaccine clinical research direction)

Flight bans, travel restrictions, border closures...

Recently, the rapid spread of the new coronavirus variant Omicron has aroused everyone's attention and concern about the new variant. As of yesterday (December 2), at least 30 countries and regions around the world have reported cases of infection with the Omicron strain.

On November 26, local time, the WHO held an emergency meeting and issued a statement, listing the new coronavirus variant B.1.1.529 as a "variant of concern" and named it Omicron.

The decision was based on a variety of factors, including the discovery of cases of Omicron infection in multiple countries and the exponential growth of cases of infection with the Omicron variant in South Africa. The mutations of the variant may reduce the effectiveness of COVID-19 vaccines and certain monoclonal antibody treatments.

Omicron new strain

Why did the Omicron variant appear?

The SARS-CoV-2 virus that causes the COVID-19 epidemic has spread around the world. The high-frequency mismatch characteristics during viral genome replication and the accumulation of gene mutations during the combined transmission and infection process ultimately led to the emergence of SARS-CoV-2 variants.

Simply put, as long as the human-originated new coronavirus continues to spread between people and persists, the emergence of mutant strains is only a matter of the degree of antigenic difference and the timing of the emergence. This is how the Omicron mutant came about.

In this way, some variants will disappear, while other variants will appear and continue to spread, and they may replace the original variants and become the dominant variants that infect a large number of people. The Omicron variant has this potential.

Image source: genomic data analysis platform nextstrain.org

The phylogenetic analysis used the earliest novel coronavirus strain (Wuhan-Hu-1/2019) as a reference. The Omicron variant is farther away than the Delta variant, suggesting that Omicron has a higher frequency of mutations. Similarly, the amino acid mutations of the Omicron variant are more likely to occur in the S spike protein region. Mutations in this part lead to potential immune escape.

Infections caused by Omicron variants at home and abroad

Global epidemic characteristics of new coronavirus variants (Based on Clade), data as of November 30, 2021

From the analysis of genetic sequencing data, clinical and epidemiological data related to the new coronavirus variants collected by the GISAID (Global Initiative of Sharing All Influenza Data) platform, it was found that the variants that caused the continued COVID-19 epidemic abroad are still mainly Delta variants (green blocks on the pie chart), supplemented by Alpha and Beta variants (blue and purple blocks on the pie chart), while Omicron infection cases account for only a small part (red blocks on the pie chart). At present, cases of infection with the Omicron variant have only been detected in Hong Kong, my country.

Compared with previous variants, what are the new characteristics of Omicron?

Currently, the Omicron variant has the most mutation sites in the S spike protein (32-35). Existing vaccine and antibody design ideas are mostly targeted at this S spike protein. In the case of the Delta variant being the dominant strain globally, the Omicron variant in South Africa has replaced the Delta variant as the dominant strain, which has attracted sufficient attention from the WHO.

How much impact will the Omicron variant have on the existing domestic monitoring and COVID-19 prevention and control system?

Faced with the Omicron variant, more pressure may fall on the quarantine and epidemic prevention of people and goods entering and leaving the country.

At the same time, the detection kit for the Omicron variant will be available in a relatively short time to fill the need for targeted identification and detection of the Omicron variant. However, we must not relax our anti-epidemic and prevention efforts.

Will the Omicron variant cause large-scale breakthrough infections?

The new coronavirus pandemic currently raging around the world is still mainly caused by the Delta variant.

At the same time, with the increasing number of people vaccinated and those who have recovered from natural infection, WHO predicts that the Omicron variant may lead to a surge in new coronavirus cases in the future. However, whether it will further lead to a global invasion requires more attention to the situation of people who have recovered from new coronavirus infection and those who have completed vaccination being infected with the Omicron variant again.

The immune escape of the new coronavirus is an essential feature of the virus to cause persistent epidemic transmission. In this process, many mutants will be produced and many mutants will disappear. The current Omicron variant is slightly eye-catching.

The Omicron variant, along with the Alpha (B.1.1.7) variant discovered in the UK, the Beta (B.1.351) variant discovered in South Africa, the Gamma (P.1) variant discovered in Brazil, and the Delta (B.1.617.2) variant discovered in India, are all listed as worrying mutants that require close attention.

As COVID-19 prevention and control becomes normalized, what else should we do?

Complete COVID-19 vaccination and booster shots promptly as required;

Wear a mask when traveling;

Keep a safe distance when talking to people in public;

Public environments are cleaned and disinfected daily according to regulations;

Reduce the number of people entering or leaving crowded or confined environments;

Always pay attention to changes in your health and seek medical attention if necessary.

It is the responsibility of every Chinese citizen to understand the scientific knowledge of epidemic prevention and comply with the epidemic prevention policy requirements of various places. More importantly, physical and mental health can work together to drive away the "haze" of the new crown epidemic.

Let’s work together!

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