Omicong BA.5 appears in Xi'an. What are the characteristics of this new mainstream strain in the world?

On July 5th, according to the announcement of the Shaanxi Provincial Center for Diseases, the Omikon mutant strain BA.5 appeared in the this round of the epidemic in Xi'an.

In early May of this year, my country found the first BA.5 infected by overseas input, but did not cause large -scale local dissemination.

43% of new cases in the world

BA.5 was first detected in South Africa in February this year. According to the World Health Organization (WHO) report on June 22, BA.5 has spread to 62 countries around the world.

According to the WHO report on June 29, in the 24th epidemiological week (June 13th to 19th), BA.5 accounted for 43%of the new cases, exceeding BA.2 (25%), becoming the mainstream strain in a new round of epidemic in the world.

The diffusion of BA.5 also caused the global epidemic that had just escaped from the BA.2 "magic claw" to rebound again.

According to the WHO report, due to the influence of BA.5/BA.4, from June 20th to June 26th, the number of new cases worldwide reached 4.1 million cases. ) Compared to 18%, the highest value since April.

Among them, the East Mediterranean, Europe, Southeast Asia and the Americas are more serious.

In the Americas, the United States and Canada are deeply influenced by BA.5.

The number of cases in Canada has recently risen again, with an average daily increase of about 2,300 new diagnosis cases, and the previous minimum value was 1561.

According to the forecast of Professor Sarah OTTO, a Canadian coronary virus variant, BA.5 will account for 70%of the new cases in early July. Affected by it, Canada will usher in a new round of epidemic peak in July.

In the United States, the number of new cases (7 -day average) in a single day has exceeded 100,000 in a row, and has not yet declined, up to 120,000 people.

According to data from the US CDC, as of June 25, the proportion of BA.5 has reached 36.6%, close to the proportion of BA.2.12.1 (42%), and it will soon become the main strain of the American epidemic.

In Europe, BA.5 has also become the main strains of many countries.

As of June 27, BA.5 also accounted for 55%, 59%, and 66%in Britain, Germany, and France, respectively.

The number of confirmed cases in Germany began to rise in early May. At present, the number of new cases in a single day is close to 90,000, which is 3.2 times the lowest value (May 6).

In Asia, the epidemic in Singapore has been reunited again.

On July 4, the number of new cases (7 days average) in Singapore reached 8,500, which was 2.65 times compared to early June.

Minister of Health of Singapore said on July 5 that patients infected with BA.4/BA.5 doubled per week, which initially accounted for only 3%of new cases; The proportion has reached 50%. He predicts that by next week, BA.4/BA.5 will become the main strain in Singapore, and the proportion of patients will reach 7 to 80 %.

Strong immune escape ability

Compared with other mutant strains, the spread of BA.5 is faster.

According to a research report released by the Institute of Medical Research, the University of Tokyo, Japan, compared to Omikon BA.2, the effective number of effective regeneration (RT value) of BA.5, that is, during the infection period, the average number of people who can infect a patient infected More.

According to research by scholars in South Africa, BA.4/5 has a growth advantage relative to BA.2, and its basic reproduction (R0) may reach 18.6, which is 5.6 times the original strain, 3.65 times of Delta, and Omik Rong Rong 1.96 times of BA.1, 1.39 times of BA.2.

The reason why BA.5 mutant strains are easier to spread, partly because of its strong immune escape ability. This shows that even if the patient has been infected with other new crown strains or vaccinated vaccines, the BA.5 can still break through the immune system and lead to re -infection.

The Institute of Medical Research, the University of Tokyo conducted a neutralized analysis of the four serum, including BA.1 infection with the recovery of the serum (unprepared vaccine), BA.1 to break through the infected recovery serum (completely vaccinated vaccine and infected again), BA.2 Infected recovery serum (uncontrolled vaccination), and serum (completely vaccinated and re -infected with BA.2), infected with BA.2, infected with the neutralization of BA.5 compared to the previous mutant Obviously decline.

Studies at the Human Genetics Center of Oxford University of Oxford in the United Kingdom also show that BA.5 has strong immune escape ability.

Within 14 days of infection of BA.1 mutant strains, the neutralization of serum on BA.5 was far from BA.1 and BA.2, respectively, respectively, respectively, respectively, respectively. After 21 days, the neutralization of serum on BA.5 decreased greater than the serum of the infected person, a decrease of 3.4 times more than the BA.1, and the BA.2 doubled.

This situation is also applicable to patients with vaccination, and the effects of different vaccines are different.

Researchers have observed that after 28 days after inoculation of three -dose Oxford/Aslekang's new crown vaccine, the infected serum has a neutralization of BA.5 virus, which has decreased by 2.1 times compared to BA.1, compared with BA.2 decreased, it has decreased. 1.8 times.

After 28 days after inoculating the new dose of Pfizer Biotechnology, the serum neutralization decreased, and the neutralization of serum on BA.5 has decreased by 3.2 times compared to BA.1 and BA.2. According to reports, the first input case of BA.5 in China had been vaccinated with 4 doses of new crown vaccines in China before the infection.

Or more pathogenicity

In addition to strong immune escape ability, BA.5 may also have a stronger pathogenicity compared to other mutant strains.

This consistent pathogenicity is reflected in multiple aspects, including the effects of different degrees such as weight, blood oxygen concentration, bronchial, and alveoli.

According to the report from the University of Tokyo, based on the research on hamsters, BA.5 is more likely to diffuse from the lungs and extraordinaries in the infection of hamsters than BA.2. After 3 days infected with the BA.5 virus, the RNA level around the hamster lung was 5.7 times that of the BA.2 virus; after 5 days of infection, the RNA level of the BA.5 was still 4.2 times that of BA.2.

Therefore, the BA.5 mutant strain is more likely to cause hamsters to cause bronchial contraction or airway obstruction. Within a week, hamsters infected with BA.5 are more prone to respiratory rapids, decreased subcutaneous oxygen saturation, and increased breathing intermittently.

At the same time, BA.5 mutant strains are also more likely to cause infected hamsters to cause bronchitis, alveolar damage, and pulmonary congestion/bleeding.

In addition, compared to BA.2 and BA.2.12.1, the BA.5 leads to a larger decrease in weight hamsters within a week, a decrease of about 10%, but the weight of the hamsters infected with the remaining strains have increased.

Of course, these pathogenicity is only reflected in the experimental hamster and cannot be directly derived to human infection. At present, countless data indicate that BA.5 can cause more serious symptoms.

However, from the perspective of Portugal's this round of epidemic conditions, the impact of BA.5 mutant strains still cannot be ignored.

Affected by BA.5 strains, Portugal entered this round of epidemic at the end of April and reached its peak in early June. The number of new cases in a single day was close to 30,000. Since then, it has gradually declined. It is currently at the end of the epidemic.

Although the number of confirmed cases is not as good as the previous round of epidemic (from the end of December 2021 to the beginning of March 2022), the peak of the number of new diagnostic people in a single day is doubled, but the peak of the newly added death person in a single day is higher than the previous one than the previous one. Run epidemic. On June 20, Portugal added 56 new deaths in a single day (7 days average), while the peak of the number of deaths on a single day in the previous round of epidemic was 52.

In early May, the European Disease Prevention and Management Center (ECDC) had included BA.5 in "deserved mutant strains" and called on countries to be vigilant. The hospital and the intensive care unit cause a burden. At the same time, ECDC also emphasized that it can still achieve a certain protective role.

Liberation Daily · Shangguan News Original manuscript, reprinting without permission

Author: Lian Junxiang

WeChat editor: Antong

School counterpart: Ta Ni

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