Xinhua News Agency, London, October 25 (Reporter Guo Shuang) In recent months, cases of infection with the submutated strain of the new crown mutant virus delta strain AY.4.2 have emerged in many countries. How powerful is this strain called “Delta+” by many media, and has it become the most powerful strain since the pandemic?
“Delta+” has another “poison”
The AY.4.2 subvariant strain, officially known as VUI-21OCT-01, is called “Delta+” by many media. However, the researchers pointed out that it can be confusing to call it that way, because “Delta+” has its own “poison” long ago. As early as before AY.4.2, there was a “descendant” of the Delta strain called the “Delta+” strain, and its mutation was not the same as that of AY.4.2. So far, on a global scale, researchers have recorded more than 40 sub-variant strains of Delta, and AY.4.2 is just one of them.
Compared with the original Delta strain, there are two typical mutations in the spike protein carried by AY.4.2 when it infects human cells, namely Y145H and A222V. Both of these mutations have been documented before. As early as April last year, researchers sequenced the first strains that carried both mutations. At the time, these two mutations did not appear special, and researchers did not include them as “variations of concern”. However, the British Health and Safety Agency pointed out that in some cases, a small change may be enough to cause a difference in virus characteristics.
The British Health and Safety Agency recently stated that at present, the agency is closely monitoring the spread of AY.4.2 subvariant strains, and through laboratory and epidemiological studies to better understand its characteristics.
It’s no accident that the mutated virus mutates again
Jenny Harris, Chief Executive Officer of the UK Health and Security Agency, previously stated: “Virus mutations are common and happen randomly. With the development of the epidemic, especially when the infection rate is high, the continued discovery of new mutated viruses is not Accident.”
Statistics show that the UK is one of the most severely affected countries in the world. Since the implementation of the final stage of “unblocking” in England on July 19 and the relaxation of epidemic prevention and control policies in other parts of the UK, the number of new cases in the UK in a single day has mostly exceeded 30,000. The British Health and Safety Agency said that since July this year, the spread of AY.4.2 subvariants in England has become more and more common. As of the 20th, 15,120 people in England have been infected with this subvariant strain. However, the researchers pointed out that the delta strain is still the main prevalent strain in the UK, and the continued high number of new cases in a single day in the UK cannot be attributed to the AY.4.2 subvariant strain.
In addition to the United Kingdom, other countries have also found traces of AY.4.2. According to data released by Outbreak.info, an epidemic tracking data website, 42 countries and regions around the world have reported cases of AY.4.2 infection. In the United States, more than 30 states have found cases of AY.4.2 infection. However, compared with the United Kingdom, the number of AY.4.2 infections in other countries and regions is relatively small.
More contagious but relatively slow growth
Judging from the data in the early stage of transmission, the “growth speed” of the AY.4.2 subvariant strain and the Alpha strain and the original Delta strain is not the same. Compared with the first spread of the new coronavirus, the infectivity of the alpha strain in the UK increased by 50% last year, and after the delta strain gradually replaced the alpha strain, its infectivity increased by 60% compared with the alpha strain.
In contrast, AY.4.2 has a smaller increase in infectivity. Jeffrey Barrett, head of the New Crown Genome Project at the Sanger Institute of the Wellcome Foundation in the United Kingdom, and others pointed out that the infectivity of AY.4.2 is 10% to 15% higher than that of the original Delta strain. The British Health and Safety Agency said that so far, there is no indication that this subvariant strain will cause more severe cases or reduce the effectiveness of the new crown vaccine.
According to data from the Sanger Institute, AY.4.2 infection cases have been steadily increasing in England. The researchers said that this may indicate that AY.4.2 has a “sustainable advantage” in spreading, but it is not clear whether this sub-variant is spreading in the UK because of mutations that give it a biological advantage over other mutant strains, or whether Other reasons cause it to spread among people with high infection rates.