According to The Paper News, recently, a joint scientific research team led by Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine (referred to as Shanghai Ruijin Hospital)Chen Saijuanand Fan Xiaohong of the Shanghai Public Health Clinical Center (referred to as Shanghai Public Health Center) added 369 new Chinese coronavirus sequencing results to the Global Initiative for Sharing All Influenza Data (GISAID) database.
It is worth noting that among the 25 cases of the Omicron subtype XBB family detected in Shanghai this time, 3 cases were XBB.1.5, which were also imported cases from abroad, and did not cause local transmission.
Previously, at the State Council Joint Prevention and Control Mechanism press conference on December 20, Xu Wenbo, director of the Institute of Viral Diseases of the Chinese Center for Disease Control and Prevention, introduced that my country has detected BF.7, BQ.1, and XBB transmission in the past three months. A total of more than 130 subclades of and were imported into my country, and 50 subclades caused associated local cases or outbreaks, including BQ.1 and XBB. Among them, BQ.1 and its subclades were detected in 49 cases in 9 provinces, and the XBB subclade of was detected in 11 cases in 3 provinces.
Symptoms of infection with XBB subtype strains include difficulty breathing, headache, sore throat, nasal congestion, body aches, fatigue and fever.
Recently, a new variant of Omicron, XBB.1.5, has spread rapidly in the United States, attracting the attention of netizens. So, what are the characteristics of this strain? Is it more pathogenic? Will it cause to infect again? Will it cause a new peak of infections?
XBB.1.5 that quickly “came to the fore”:
was first discovered in New York, It has become the most popular strain in the United States
. In the Omicron family, the BQ series subtype strains belong to the BA.5 branch, and the XBB series strains that have attracted recent attention are recombinants of the BA.2.75 and BJ.1 sublines derived from BA.2.
According to CCTV News, in June 2022, the BQ.1 variant was first discovered among Nigerian infected people. In September, BQ.1 and its derived sub-branches began to become popular in European and American countries, with their proportion increasing month by month. In mid-October, they gradually became popular in Asian countries and regions such as Japan and Singapore.
In addition to the mutations found in BA.2, the spike of the XBB subvariant has 14 more mutations, 5 of which are in the N-terminal domain (NTD) and 9 in the receptor binding domain (RBD), while XBB.1 has an additional G252V mutation.
↑In just one week, the proportion of XBB.1.5 infections in the United States doubled
Subsequently, the Omicron subtype strain named XBB.1.5 was discovered in New York, USA, and quickly swept across the United States.
On December 13, 2022, the magazine "Cell" published online the latest research on the Omicron subtype strains BQ and XBB families by the team of Colombian AIDS expert He Dayi. The study found that the BQ and XBB series variants are farther away from Omicron BA.5 than Omicron BA.5 is from the original Omicron strain, and the degree of drift or transfer of their antigen (i.e., the degree of mutation) is comparable to that of the original Omicron strain .
↑"Cell" screenshot
According to Overseas Network News on January 1, according to NBC and other US media reports, the US Centers for Disease Control and Prevention stated that the new variant of Omicron XBB.1.5 is spreading rapidly in the United States. Currently, 40% of new crown confirmed cases are infected with this new variant, higher than 20% the previous week. In the northeast region of , about 75% of confirmed cases are infected with XBB.1.5.
Barbara, director of the Respiratory Viruses Division at the U.S. Centers for Disease Control and Prevention, said there is no indication that XBB.1.5 causes more severe disease than other Omicron variants. While COVID-19 hospitalization rates are rising across the country overall, hospitalization rates are not rising in the Northeast.
↑In the week ending December 31, XBB.1.5 accounted for 40% of U.S. COVID-19 cases
Compared with other Omicron strains
None There are signs that XBB.1.5 will cause more serious diseases
Recently, a screenshot claiming that the XBB.1.5 strain attacks the digestive system and suggesting stocking up on medicines was widely circulated. norfloxacin and montmorillonite powder mentioned in the screenshot subsequently appeared on hot searches, sparking discussion.
According to CCTV News, Xu Wenbo, director of the Institute of Viral Diseases of the Chinese Center for Disease Control and Prevention, said that the pathogenicity of BQ.1 and XBB is not significantly different from other series of Omicron mutant strains, and the severity and mortality rates have not increased in countries where BQ.1 and XBB are prevalent.
In this regard, Li Zhiling, deputy director of the Pharmacy Department of Shanghai Children's Hospital, also said in an interview with the media that some people infected with the new coronavirus do have symptoms of vomiting and diarrhea, which usually resolve on their own in 1-3 days. The more important thing about treating diarrhea with is to prevent dehydration and water and electrolyte disorders. Montmorillonite powder should be used under specific circumstances. Blind use of will add chaos, and stocking up on medicines is even more unnecessary.
According to the latest reports on December 31, over the past two weeks, the average number of people hospitalized with new coronavirus infections in the United States per day has increased by 4.2%, reaching 42,324. However, Barbara, director of the Division of Respiratory Viruses at the U.S. Centers for Disease Control and Prevention, said hospitalization rates in the Northeast, where XBB.1.5 is dominant, are no higher than in areas where other strains are dominant. Currently, there is no indication that XBB.1.5 causes more severe disease than other Omicron strains.
may be the most powerful immune evasion strain in history
, but its transmissibility may not change significantly
In addition to its pathogenicity, whether the new strain can be induced by vaccine and protected by natural immunity is also the most concerning issue.
Since XBB.1.5 has the F486P mutation, which allows it to better bind to cells, it is easier than other strains to break through the body's immune defense system. The latest research by He Dayi's team on the Omicron subtype strain BQ and XBB families also confirmed this.
Researchers compared and analyzed blood samples from people who received three or four doses of the original COVID-19 vaccine , people who received the Omicron booster vaccine after three doses of the original COVID-19 vaccine, and people who developed a breakthrough infection due to the BA.2 or BA.5 strain after vaccination. The results showed that the neutralizing ability of the new coronavirus vaccine and the sera of previously infected persons against BQ.1, BQ.1.1, XBB and XBB.1 was significantly reduced. The neutralizing titers against BQ and XBB were reduced by 13-81 times and 66-155 times respectively, but it was not a complete immune escape. This means that the increase in subvariants such as XBB may further undermine the protective efficacy of current COVID-19 vaccines, leading to a surge in breakthrough infections and reinfections.
↑Schematic diagram of XBB and BQ.1.1 spike mutations
The researchers further analyzed through surface plasmon resonance technology (SPR) and found that the binding ability of BQ.1 and BQ.1.1 spikes to ACE2 is equivalent to that of BA.4/5. The binding ability of XBB and XBB.1 spikes to ACE2 is slightly lower than that of BA.2, which may be due to the F486S and R493Q mutations located at the top of the binding domain (RBD) of the receptor. The researchers concluded that the SPR analysis provided no evidence that the increase in new variants was due to a higher ability to bind ACE2.
As a result, the BQ and XBB series have gradually become the most popular strains in the world, possibly because they have stronger immune evasion capabilities rather than stronger transmissibility. However, another study by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington also showed that the XBB variant is more contagious than the earlier version of Omicron.
It is better to receive a booster shot of heterogeneous vaccine
Small molecule drugs are still effective
Despite this, the research of He Dayi's team also pointed out that against the new Omicron subtype strain XBB, the effect of the booster vaccine is slightly better than the original vaccine. The researchers emphasize in the article that vaccination is still effective in preventing hospitalization and severe illness and may reduce the risk of sequelae.
On December 31, Rick Bright, an American immunologist and former director of the Biomedical Advanced Research and Development Authority (BARDA), also pointed out in an interview that "Singapore's experience with XBB strain infections is encouraging." He said that in the previous wave of infections caused by XBB, despite the surge in infection cases in Singapore, there was no corresponding significant increase in hospitalizations and deaths. "We believe this is because more people in Singapore have received the latest vaccine and the Omicron vaccine booster shot."
Previously, at the second Greater Bay Area (Shenzhen) Vaccine Summit, Zhong Nanshan, academician of the Chinese Academy of Engineering, , mentioned in his speech about the booster shot after full vaccination that after two doses of inactivated virus vaccine, the third dose of the vaccine is effective and has been proven to have enhanced clinical protection in the real world. In addition, after two doses of inactivated virus vaccine, vaccination with mRNA vaccine was significantly effective. After two doses of inactivated virus vaccine, vaccination with subunit protein vaccine was significantly effective. After two doses of inactivated virus vaccine, vaccination with adenovirus vector vaccine was significantly effective.
Zhong Nanshan clearly pointed out that vaccination with heterogeneous types of vaccines may be more effective, but further observation of the protection rate in the real world is needed to confirm it.
In addition, another issue worthy of attention is that the research by He Dayi's team also found that monoclonal antibodies are "essentially inactive" against new subvariants. However, according to a study published in the New England Journal of Medicine on December 9, although monoclonal antibodies are ineffective against BQ.1.1 and XBB, only small molecule drugs targeting conservative targets still maintain efficacy.
Can medical institutions cope with the new strain? |
On January 1 this year, according to CCTV's "Face to Face" program, many cities began to experience a peak of new coronavirus infections in early December 2022, and the number of infected patients surged. The hospital's fever clinics were first under pressure.
Regarding the question of whether XBB.1.5 will cause a new round of infection peak in mainland China, Professor Zhang Jiming, deputy director of the Department of Infectious Diseases at Huashan Hospital affiliated to Fudan University, responded to China News Service: "There is no need to worry, it is a bit exaggerated."
Zhang Jiming said that the new strain currently monitored still belongs to the Omicron subtype and is still a respiratory virus, that is, it mainly infects respiratory tract , and its pathogenicity has not increased. At the same time, combined with the experience of handling the first round of infection peak, medical resources can cope with it.
Jin Dongyan also said that the emergence of XBB.1.5 in the United States has not changed the basic trend of the new crown becoming endemic in the United States. In his view, there is currently no ground for a tsunami-like outbreak of COVID-19 in the United States. XBB.1.5 has not changed this ground, and has not caused a major outbreak in the United States similar to the BA.2 outbreak at the beginning of the year.
What you need to know about the XBB strain
Red Star News reporter Xu Xu
Comprehensive CCTV News, People's Daily , China News Network
