Reporter | Liu Zixiang
Editor |
Just as Europe and the United States are facing another wave of infection caused by BA.4 and BA.5, a new generation of variants evolved from Omickron are coming again. The new variant of
was first discovered in India in early June and has not been officially named. Some people call it BA.2.75, while researchers call it Centaurus (Sagittarius) as the code name. The Omickron variant BA.2 is its original strain, which researchers call the "second generation" variant. In addition to India, it has also been found in Japan, Germany, the United Kingdom, Canada, the United States, Australia and New Zealand . Compared with BA.2.75,
has 8 spike protein mutations. The location of these mutations has worried scientists that it may escape the immunity established by BA.2. In other words, people infected with BA.2 may re-infect BA.2.75. Many mutations mean higher chances of escaping the epidemic.
7 On July 6, WHO Director-General Tedros Adhanom Ghebreyesus said at a press conference that he was conducting close monitoring of BA.2.75. WHO experts suggest that BA.2.75 looks different from the previous variant, but also stressed that it is too early to judge its severity.
A day ago, WHO chief scientist Soumya Swaminathan said on social media that about 10 countries have reported BA.2.75, but it has not been declared a worrying variant. Its transmission, degree of pathogenicity, and possibility of immune evasion are not yet known.
But many experts have expressed hidden concerns. Ulrich Elling, a geneticist and molecular biologist at the Austrian Academy of Sciences, told Deutsche Welle that so far there are very few data on this variant, with only about 70 recorded BA.2.75 cases worldwide. But he also pointed out that testing efforts in many countries have decreased significantly, and he believes that the number of unreported cases may be rising.
According to the Indian livemint news network, 8 countries (including India) have reported 85 BA.2.75 cases so far. As of July 6, 10 states in India have reported BA.2.75, including Delhi and Maharashtra .
According to the results of sequencing of Indian infection strains by the Global Avian Influenza Gene Sharing Database (GISAID), BA.2.75 accounted for 23% of the Indian sample in early July.
The aforementioned Austrian Academy of Sciences Ellin stressed that so far, experts have no definite understanding of BA.2.75. However, considering that India has experienced a wave of BA.2 infection, the fact that BA.2.75 can spread in multiple regions of India seems to be a sign of its strong immune evasion ability.
Imperial College London virologist Tom Peacock wrote on Twitter that he believes the multiple mutational characteristics of BA.2.75 and the extensive geographical spread make it worthy of close attention.
In fact, because there is little information in hand, scientists can only speculate on the trajectory of BA.2.75. Elling said: "It seems that something is coming towards us, but there is no certain evidence yet." Although
The face of BA.2.75 is still vague, it is an indisputable fact that BA.4 and BA.5 are setting off a wave of infection in Europe and the United States.
htmlOn July 6, WHO Director-General Tedros Adhanom Adhanom Adhanom 5 pointed out that in European and American countries, BA.4 and BA.5 are causing a new wave of epidemics. BA.5 has been detected in 83 countries and BA.4 has been detected in 73 countries.. In the past two weeks, the number of reported cases of new crown
in the global has increased by nearly 30%; last week, four of the six WHO subregions experienced an increase in cases. Considering that many European and American countries have cancelled testing, the actual infection situation may far exceed the above figures.BA.5 is dominant in the United States. According to US CDCh data, BA.5 caused nearly 54% of new infections in the United States last week. As of July 2, BA.4 and BA.5 accounted for 70% of the United States.
BA.5 has also been logged in China. On July 5, Xi'an detected BA.5.2. On the 6th, Beijing's COVID-19 prevention and control press conference stated that the specimens of three infected people reported the day before were genetically sequenced, and the results showed that the viruses all belonged to BA.5.2.
In the spring of this year, BA.5 swept across South Africa with twin variant BA.4, and they all have the ability to escape the immunity built by previous infections and vaccination.
A recent study in South Africa found that in the face of BA.4 and BA.5, neutralizing antibodies dropped by nearly 8 times in people who had previously been infected with Omickron but were not vaccinated. The antibodies of people who have both been infected with Omickron and were vaccinated have dropped by three times.
Eric Topol, director of the Scripps Research Institute, said last week that BA.5 is the worst version of the virus we have ever seen, bringing already high immune escape to the next level and enhancing transmission, far exceeding what we have seen before.
study said that BA.4 and BA.5 are almost six times more contagious than the original strain of the new crown, similar to the infectiousness of measles . In addition to the faster transmission speed and higher viral load, many experts said in an interview with the media that compared with previous mutant strains of Omickron, BA.5 has a new situation of invading the lower respiratory tract such as the lungs and having strong immune escape ability.
Tedros said at a press conference on the 6th that multiple factors have made the challenges of the epidemic more complicated. For example, the number of tests in many countries has dropped significantly, covering up the real situation of the continuous evolution of the virus and the real burden of the global COVID-19 epidemic.
In addition, new oral antiviral drugs are difficult to obtain, and new treatments are still not delivered to low- and middle-income countries. In addition, the effectiveness of the vaccine has decreased. As the virus continues to develop, the protective effect of the vaccine has indeed weakened, which highlights the importance of strengthening the injection.
Tedros called for adherence to epidemic prevention measures, especially where cases are on the rise. We must also accelerate the research and development of next-generation vaccines, testing and treatment tools.
WHO COVID-19 incidents Abdi Mahamud said we are still in the midst of a pandemic and the virus still has a lot of strength. Whether it is BA.4, BA.5 or BA.2.75, the virus will continue to exist.
