Another new coronavirus mutant strain “churns” the world.
The highly contagious mutants of the new coronavirus, Omicron subtypes BA.4 and BA.5, are causing a surge in the number of new crown hospitalizations in European countries. Among them, the epidemic situation in Portugal is the most severe. BA.4 and BA.5 have become the most mainstream mutants in the country. The positive detection rate was as high as 50.63%. The wave peaked in March; hospitalizations are also rising in France, the United Kingdom, and Germany, according to analysis by the Financial Times.
At the same time, Omicron BA.4 and BA.5 spread very fast in the United States. In just 35 days, the proportion of infections soared by 21 times. Rockefeller University virologist Paul Bieniasz warned that millions of Americans could be reinfected in the future.
A new study concluded that Omicron BA.4 and BA.5 have stronger cell fusion ability than BA.2 in alveolar epithelial cells. It means that compared with BA.1 and BA.2, which mainly infect the upper respiratory tract, BA.4 and BA.5 can walk the lungs better.
While the new coronavirus continues to mutate, a newly disclosed rare case has attracted global attention. The latest issue of Emerging Infectious Diseases, an academic journal of the U.S. Centers for Disease Control and Prevention, published a study disclosing a suspected case of “cat-to-human” transmission of the new coronavirus in Thailand, the first case in the world.
Covid-19 hospitalizations surge
The strongest mutant strain of Omicron: BA.4 and BA.5 variants are sweeping Europe, and many countries are facing the test again.
Among them, the epidemic situation in Portugal is the most severe. At present, BA.4 and BA.5 have become the most mainstream mutant strains in Portugal, and the positive detection rate was as high as 50.63%. In the past month, the number of new crown hospitalizations in Portugal has also increased significantly, almost equivalent to 1 The number of new deaths in a single day also returned to the level at the peak of the infection in Omicron.
Statistics from the Pandemic Surveillance Task Force of the University of Lisbon say that the peak in hospitalizations in wards and intensive care units (ICUs) in Portugal will continue until the end of June this year.
On June 17, local time, the British “Financial Times” reported that the highly contagious Omicron BA.4 and BA.5 have led to a surge in the number of new crown hospitalizations in European countries at a time when immunity levels have declined and epidemic restrictions have been lifted. , which may trigger a new round of global epidemics.
The number of hospitalisations is rising in some countries, including France and the UK, according to an analysis by the Financial Times. In Germany, the number of hospitalizations for the new crown has continued to rise for more than a week, and the proportion of infections caused by BA.5 doubled at the end of last month.
Piotr Kramarz, head of surveillance at the European Centre for Disease Prevention and Control, warned that the new subvariants BA.4 and BA.5 of Omicron are capable of “immune escape”, which means that neither antibodies nor vaccines developed after previous infections can provide Strong protection, which also prompts the new variant to dominate.
Earlier, the European Centers for Disease Control and Prevention warned that the spread of Omicron BA.4 and BA.5 in Europe is faster than other variants, which may lead to more related confirmed cases, and the number of hospitalizations and deaths will rise. .
At the same time, the BA.4 and BA.5 variants spread very quickly in the United States. In just 35 days, the proportion of infections soared 21 times. The latest surveillance data from the U.S. Centers for Disease Control and Prevention shows that as of June 11, the combined proportion of infected Omicron BA.4 and BA.5 had reached 21.6%, while on May 7, BA.4, BA. 5 Consolidation accounts for only 1% in the United States.
Rockefeller University virologist Paul Bieniasz believes that several variants of Omicron may each dominate different parts of the United States, and millions of Americans are likely to be reinfected in the future.
According to CDC data, on June 16, local time in the United States, there were 143,000 new cases of new crowns and 526 new deaths. Two months ago, the number of new cases in the United States was around 30,000 a day.
Omicron BA.4 and BA.5 can walk the lungs better?
At present, Omicron BA.4 and BA.5 have promoted a new wave of infections in some countries, but they have not surpassed the influence of BA.2.12.1. Early data from the UK suggest that Omicron BA.4, BA.5 may spread slightly faster than the BA.2.12.1 variant, but the exact circumstances are not known.
It should be pointed out that it took just over a month for the Omicron BA.2.12.1 variant to become the “culprit” for most of the new coronavirus cases in the United States.
As for the pathogenicity study of BA.4/5, 27 scientific research units from Tokyo University, Kyoto University, Hokkaido University, Kyushu University, Kobe University, Israel Weizmann Institute of Science and other 27 research institutes have previously cooperated on the medical preprint website bioRxiv Published a major study, showing that the replication efficiency in human alveolar epithelial cells is higher than BA.2, especially BA.4, BA.5 have stronger cell fusion ability in alveolar epithelial cells than BA.2.
It means that compared with BA.1 and BA.2, which mainly infect the upper respiratory tract, BA.4 and BA.5 can walk the lungs more. The experiment shows that the plaques formed by BA.4 and BA.5 on human alveolar epithelial cells are larger than BA. .2 Plaque formed by infection.
It is worth noting that the new variants of Omicron BA.4 and BA.5 can escape natural immunity and the efficacy of the original strain vaccine. An international organization including a Columbia University team, a Japanese consortium and South African scientists conducted a study on the protective effects of antibodies produced after infection on BA.4 and BA.5. The “old variants” of 1 and BA.2 are several times more effective than BA.4 and BA.5.
Virologist Bieniasz predicts that the virus will continue to re-evolve around the immune system, so new vaccines may need to be developed to increase protection against infection, such as Moderna’s booster shot for the Ormicon strain.
From a global perspective, most of the confirmed cases of the new crown are still caused by the subvariant BA.2.12.1 of Omicron, but more and more infectious disease experts believe that the new cases caused by BA.4 and BA.5 The number may exceed BA.2.12.1 in the future, or become a new mainstream strain in the world.
At present, everyone is more concerned about whether the toxicity of Omicron BA.4 and BA.5 has weakened. To date, data reflecting the toxicity of the new variants are still limited. But scientists remain optimistic, given the research published by South Africa.
The South African side stated that compared with the BA.1 variant, the number of hospitalizations and deaths during the epidemic of the BA.4 and BA.5 variants accounted for less. Meanwhile, the European Centre for Disease Control and Prevention said the Omicron BA.4, BA.5 variants did not appear to cause severe disease.
a rare case
Omicron’s continued mutation is causing tensions in medical research institutions around the world. A newly discovered rare case has drawn global attention.
The latest issue of Emerging Infectious Diseases, an academic journal of the U.S. Centers for Disease Control and Prevention (CDC), published a study revealing a suspected case of cat-to-human transmission of the new coronavirus in Thailand.
The study concluded that a 32-year-old healthy female veterinarian in Thailand was infected with the new coronavirus by a cat through epidemiological investigations and viral genome sequencing, which is the first case discovered in the world.
According to foreign media reports, researchers from the School of Medicine of Prince of Songkla University in Thailand, the School of Veterinary Sciences of Prince of Songkla University and other institutions found that in August 2021, after a father and son were infected with the new crown virus, their cats were sent to the pet hospital. When a veterinarian was sampling the cat, the cat sneezed into the veterinarian’s face.
About 5 days after the cat was sampled, the veterinarian developed symptoms such as a cough and runny nose, and the cat subsequently tested positive. After testing, the genome of the new coronavirus infected by the veterinarian is the same as that of the cat.
At that time, the veterinarian was wearing a mask, but the droplets had the possibility of spreading to the veterinarian’s eyes. The cat was most likely infected by the owner, and then the virus was transmitted to the veterinarian through droplets, that is, “human-to-cat, cat-to-human” .
The researchers concluded that their study proved that cats can transmit SARS-CoV-2 to humans. However, this incidence of transmission is relatively uncommon because cats shed live virus for a short duration (median 5 days).
At the same time, another study on Omicron also sparked heated discussions, concluding that infection with Omicron mutants after vaccination may not necessarily lead to enhanced immunity, and may also weaken the resistance to new mutations in the future. the immune capacity of the strain.
The above conclusion comes from a recent study published in the international authoritative academic journal Science, “The immune-boosting effect of infection with Omicron mutants depends on previous exposure to the new coronavirus.”
The study found that the immunity brought by infection with Omicron is poor in response to re-infection of Omicron itself, which provides a poor natural immunity boost. The same is true.
Danny Altmann, author of the paper and a professor in the Department of Immunology and Inflammation at Imperial College London, said that the Omicron variant is far from being a natural, benign booster for vaccine immunity as you might have previously thought. Instead, it is a particularly stealthy immune escaper. .
Altmann further stated that not only can Omicron break through vaccine defenses, but it appears to leave little mark on the immune system, which is more stealthy than previous mutants, and the immune system can’t seem to remember it.
Therefore, the paper concludes that infection with Omicron does not effectively increase immunity to future re-infection with Omicron.