Viruses also "involve"? Omicron's "stealth variant" gradually becomes mainstream

Recently, many Israeli media reported that the country has found at least 20 cases of infection with the BA.2 variant of the Omicron strain of the new coronavirus. This variant has more mutations than the original Omicron strain, which has caused concern among some experts.

Coincidentally, recently, several researchers who are tracking the evolution of the new coronavirus have warned on social media that the BA.2 variant of the Omicron strain is appearing in many countries and is even beginning to gradually replace the earlier BA.1 variant.

This "involution" shows that the BA.2 variant may be more contagious.

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According to the coronavirus genome data uploaded to the GISAID platform by various countries, the BA.2 variant was very rare before mid-December, but its number has risen rapidly since then. The BA.2 variant has been found in dozens of countries around the world, including the United Kingdom, the Philippines, Canada, and Germany.

According to a related article published in the "China CDC Weekly" on January 3 by researchers from the Guangdong Provincial Center for Disease Control and Prevention, the world's earliest BA.2 variant sample was discovered in South Africa on November 27, 2021. On December 28, the Guangdong Provincial Center for Disease Control and Prevention discovered that an imported case from abroad was infected with the BA.2 variant.

It is particularly noteworthy that the BA.1 variant will have off-target spike protein genes (SGTF) in PCR testing, which is an important feature that distinguishes it from strains such as "Delta", so it is easier to detect. However, the genome of the BA.2 variant does not have the characteristic deletion that causes off-target spike protein genes. PCR testing is difficult to distinguish this variant from other strains, and more complex and time-consuming methods such as gene sequencing are required to clarify it. Therefore, the BA.2 variant is also called "Invisible Omicron".

In fact, there is another variant of the Omicron strain, BA.3, but the number is very small, with only 33 samples found worldwide. Currently, researchers in Israel and other countries are closely tracking the spread of the BA.2 variant of the Omicron strain, and its infectiousness and pathogenicity are still under study.

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Regarding Omicron, the latest authoritative answer is here!

Regarding the Omicron variant, the National Health Commission organized experts from the Chinese Center for Disease Control and Prevention to provide the latest answers to relevant questions:

1. Discovery and prevalence of Omicron variants

On November 9, 2021, South Africa first detected a new coronavirus variant from case samples. On November 26, the World Health Organization named it the Omicron variant. The global coronavirus database GISAID shows that as of January 17, 2022, 118 countries have submitted 374,314 Omicron virus genome sequences. Currently, the Omicron variant has become the dominant strain in the world.

The Omicron variant was first imported into Hong Kong, my country on November 27, 2021, and was first imported into mainland my country on December 9.

2. Transmission of the Omicron variant

Epidemiological data from multiple countries suggest that the transmission ability of the Omicron variant is stronger than that of other variants. The World Health Organization's briefing on Omicron on December 23, 2021 showed that its household secondary infection rate was 15.8%, higher than Delta's 10.3%. Data from the UK Health Security Agency showed that from December 19 to 20, 2021, 90% of new coronary pneumonia cases in London and 76% in England were infected with the Omicron variant. Data from the US Centers for Disease Control and Prevention website showed that in the week from December 26, 2021 to January 1, 2022, 95.4% of new coronary pneumonia cases in the United States were infected with the Omicron variant.

3. Effectiveness of existing vaccines in preventing infection with the Omicron variant

Current research results show that the Omicron variant has not completely escaped the immune escape of existing vaccines; existing vaccines still have a certain protective effect against the Omicron variant, but their ability to prevent infection has decreased; the Omicron variant has not been found to cause an increase in the severity and mortality rates, and existing vaccines are still effective in preventing severe illness and death against the Omicron variant.

4. Impact of Omicron variants on existing nucleic acid detection reagents

Genomic analysis of the Omicron variant showed that its mutation site was not located in the target region of the nucleic acid detection reagent primers and probes published in the eighth edition of my country's "New Coronavirus Pneumonia Prevention and Control Plan", and did not affect the sensitivity and specificity of my country's mainstream nucleic acid detection reagents.

5. Measures taken by relevant countries and regions

In view of the rapid spread of the Omicron variant around the world, the United States, the United Kingdom, Russia, the European Union and other countries have recently recommended that the public strengthen daily hygiene protection (hand washing, wearing masks and safe social distancing), and that health departments strengthen disease monitoring and vaccination, especially the administra- tion of booster shots of the new coronavirus vaccine for frontline medical staff.

6. my country’s response measures

my country's overall strategy of "preventing imports from abroad and domestic rebound" and the general policy of "dynamic zeroing" are still effective against the Omicron variant. The China CDC has established a specific nucleic acid detection method for the Omicron variant and continues to conduct viral genome monitoring for possible imported cases and related local cases, which is conducive to the timely detection of Omicron variants that may be imported or related to the local area.

7. World Health Organization's recommendations on responding to the Omicron variant

The World Health Organization recommends that countries strengthen monitoring, reporting and research on the new coronavirus, and take effective public health measures to block the spread of the virus. It is recommended that individuals keep at least 1 meter away in public places, wear masks, open windows for ventilation, keep hands clean, cough or sneeze into elbows or tissues, get vaccinated, etc., and avoid poorly ventilated or crowded places. At present, all variants may cause severe illness or death. Therefore, preventing the spread of the virus is always the key, and the new coronavirus vaccine is still effective in reducing severe illness and death.

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8. What should the public pay attention to in their daily life and work in the face of the Omicron variant?

(1) Wearing a mask is still an effective way to block the spread of the virus, and it is also applicable to the Omicron variant. Even if you have completed the full vaccination and received the booster shot, you still need to wear a mask in indoor public places, public transportation, etc. In addition, you should wash your hands frequently and ensure indoor ventilation.

(2) Monitor your personal health. If you have suspected symptoms of COVID-19, such as fever, cough, shortness of breath, etc., monitor your body temperature in a timely manner and seek medical treatment.

(3) Reduce unnecessary travel. Try not to travel to high-risk countries or regions. If you must travel, strengthen personal protection during the trip to reduce the risk of infection with the Omicron variant. Pay close attention to local clustered epidemics in China. Do not travel to counties (cities, districts, banners) with epidemics unless necessary. Residents in places with epidemics should not leave their places of residence unless necessary.

Comprehensive sources: National Health Commission official website, Xinhua News Agency, Science and Technology Daily, etc.