Does "Omicron" affect existing vaccines and nucleic acid testing? Authoritative answer from the National Health Commission

Regarding the Omicron variant of the novel coronavirus, the National Health Commission organized experts from the Chinese Center for Disease Control and Prevention to answer relevant questions:

1. Discovery and prevalence of Omicron variants

On November 9, 2021, South Africa detected a new coronavirus B.1.1.529 variant from case samples for the first time. In just two weeks, the variant became the absolute dominant variant of new crown infection cases in Gauteng Province, South Africa, and grew rapidly. On November 26, the WHO defined it as the fifth "variant of concern" (VOC), named after the Greek letter Omicron (Omicron) variant. As of November 28, South Africa, Israel, Belgium, Italy, the United Kingdom, Austria and Hong Kong, China, have monitored the import of this variant. The import of this variant has not been found in other provinces and cities in my country. The Omicron variant was first discovered and reported in South Africa, but it does not mean that the virus evolved in South Africa, and the place where the variant was discovered is not necessarily the place of origin.

2. Possible reasons for the emergence of the Omicron variant

According to the information currently shared by the COVID-19 database GISAID, the number of mutation sites in the COVID-19 Omicron variant is significantly higher than that of all the COVID-19 variants prevalent in the past two years, especially in the viral spike protein. It is speculated that the reasons for this may be the following three situations:

(1) After being infected with the new coronavirus, immunocompromised patients undergo a long period of evolution in their bodies and accumulate a large number of mutations, which are then transmitted by chance;

(2) A certain animal population is infected with the new coronavirus, and the virus undergoes adaptive evolution during the spread of the animal population, with a mutation rate higher than that of humans, and then spills over to humans;

(3) This variant strain has continued to be prevalent for a long time in countries or regions where the monitoring of the genome mutation of the new coronavirus is lagging behind. Due to insufficient monitoring capabilities, the intermediate generation viruses of its evolution were not discovered in a timely manner.

Comparison of spike protein mutations of the Delta strain and the Omicron strain (Photo from Rome Children's Hospital)

3. Transmissibility of the Omicron variant

Currently, there is no systematic research data on the transmissibility, pathogenicity, and immune escape ability of the Omicron variant in the world. However, the Omicron variant also has important amino acid mutation sites in the spike proteins of the first four VOC variants, Alpha, Beta, Gamma, and Delta, including mutation sites that enhance cell receptor affinity and viral replication ability. Epidemiological and laboratory monitoring data show that the number of cases of infection with the Omicron variant in South Africa has surged and partially replaced the Delta variant, and its transmissibility needs further monitoring and research.

4. Impact of Omicron variants on vaccines and antibody drugs

Studies have shown that if the S protein of the new coronavirus has K417N, E484A or N501Y mutations, it indicates an enhanced ability to escape the immune system. The Omicron variant also has a triple mutation of "K417N+E484A+N501Y". In addition, the Omicron variant also has multiple other mutations that may reduce the neutralizing activity of some monoclonal antibodies. The superposition of mutations may reduce the protective efficacy of some antibody drugs against the Omicron variant, and the ability of existing vaccines to escape the immune system needs further monitoring and research.

5. Does the Omicron variant have any impact on the nucleic acid detection reagents currently used in my country?

The genomic analysis of the Omicron variant showed that its mutation sites did not affect the sensitivity and specificity of mainstream nucleic acid detection reagents in my country. The mutation sites of the Omicron variant are mainly concentrated in the highly variable region of the S protein gene, and are not located in the target regions of the nucleic acid detection reagent primers and probes published in the eighth edition of the "New Coronavirus Pneumonia Prevention and Control Plan" (the ORF1ab gene and N gene announced to the world by the Institute of Viral Diseases of the Chinese Center for Disease Control and Prevention). However, data from multiple laboratories in South Africa suggest that nucleic acid detection reagents with the S gene as the detection target may not be able to effectively detect the S gene of the Omicron variant.

6. Measures taken by relevant countries and regions

In view of the rapid spread of the Omicron variant in South Africa, many countries and regions including the United States, Britain, the European Union, Russia, Israel, Taiwan and Hong Kong have restricted the entry of travelers from southern Africa.

7. my country’s response measures

my country's prevention and control strategy of "preventing imports from abroad and preventing rebound from within" is still effective against the Omicron variant. The Institute of Viral Diseases of the Chinese Center for Disease Control and Prevention has established a specific nucleic acid detection method for the Omicron variant and continues to conduct viral genome monitoring for possible imported cases. The above measures will help to promptly detect the Omicron variant that may be imported into my country.

8. WHO recommendations on responding to the Omicron variant

WHO 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 recommends that individuals take effective infection prevention measures, including maintaining a distance of at least 1 meter in public places, wearing masks, opening windows for ventilation, keeping hands clean, coughing or sneezing into elbows or tissues, getting vaccinated, etc., and avoiding poorly ventilated or crowded places.

It is not yet clear whether the Omicron variant is more transmissible, pathogenic, and immune-evading than other VOC variants, and relevant research will yield preliminary results in the next few weeks. However, it is known that all variants can cause severe illness or death, so preventing the spread of the virus is always the key, and the COVID-19 vaccine is still effective in reducing severe illness and death.

9. In the face of the newly emerged Omicron variant of the new coronavirus, what should the public pay attention to in their daily life and work?

(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 booster shots, 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 entry and exit. In just a few days, many countries and regions have reported the importation of the Omicron variant. my country is also at risk of importing this variant, and the global understanding of this variant is still limited. Therefore, we should try to reduce travel to high-risk areas and strengthen personal protection during travel to reduce the chance of infection with the Omicron variant.

Beijing Daily Client Reporter Yang Xujun

Producer: Tong Shuquan

Intern Editor: Qian Feifan