Xinhua News Agency, Beijing, May 15 (Reporter Zhang Ying) Due to the significant increase in transmission capacity, the Omicron strain quickly replaced Delta and became the world's most prevalent new coronavirus strain.
The Ormicron strain also shows a strong ability to continuously evolve, and has evolved many subtypes so far.
For the frequent mutation of the Austrian McCormick Rong strains, the new crown existing vaccines can also provide protection?
Reinforcing needles significantly improve protection
In the weekly epidemic report released by the World Health Organization on the 11th, the conclusions of 23 studies evaluating the protective efficacy of the existing new crown vaccines against the infection of the Omicron strain were summarized.
The studies came from 10 countries including Brazil, Canada, the Czech Republic, and Denmark, and evaluated marketed vaccines such as Pfizer, Moderna, AstraZeneca, Sinovac and Janssen.
Some of the studies evaluated only the effect of completing the routine vaccination, some only evaluated the effect of a booster dose of the vaccine, and some evaluated the effect of both.
The results show that, compared with the alpha strain and other four new coronavirus variants classified as "requires attention", the routine vaccination of the new crown vaccine is effective in preventing Omicron strain infection, symptomatic infection and causing severe disease. have declined.
However, it is worth noting that in most studies, the existing vaccines are still highly effective in preventing severe disease caused by Omicron; in all relevant studies, a booster dose of the vaccine significantly improved the vaccine's effectiveness in preventing Omicron. The effects of infection, symptomatic infection and severe illness.
In terms of the effect of booster shots, the 36 related evaluations involving multiple vaccine booster shots involved in the study showed that within 14 days to 3 months after receiving a dose of booster shots, the effect of preventing severe illness caused by Omicron was significantly improved. 34 assessments showed that the effective rate of preventing severe illness was higher than 70% within 14 days to 3 months after a booster dose was given.
Of the 20 longer-term efficacy evaluations of mRNA vaccine booster shots, 18 evaluations showed that within 3 to 6 months after a dose of mRNA vaccine booster shot, the effective rate of preventing severe illness was more than 70%.
The WHO pointed out in its weekly report that in the future, it is necessary to evaluate the effect of vaccination booster shots beyond 6 months to understand the protective efficacy of the vaccine over a longer period of time.
Be wary of new subtypes of immune escape
What needs to be vigilant is that the Omicron strain has recently evolved some new subtypes, including BA.4, BA.5 reported by South African researchers, and BA.2.12.1 that is rapidly spreading in the United States.
The website of the American "Science" magazine published an article on the 10th that, similar to the earlier Omicron subtypes, the three subtypes BA.4, BA.5 and BA.2.12.1 are highly resistant to vaccination against the new crown or previous infection with the new crown. The antibodies produced show the ability to escape, but in most cases immunity acquired through vaccination or natural infection still protects against severe disease caused by the new subtype strain.
This article describes two preprint studies published recently.
One was published on the Archives of Medical Papers Network by researchers at institutions including the African Institute of Health Research in South Africa.
Studies have shown that BA.4 and BA.5 can evade immunity and lead to symptomatic infection in some people who have been previously infected with the Omicron subtype strain BA.1 and thus acquired immunity, especially in the future. This phenomenon is more pronounced in the vaccinated population.
This suggests that BA.4 and BA.5 have the potential to spark a new "wave of infection".
Another study, published on the "Research Square" website by a team led by researchers from Peking University's Center for Biomedical Frontier Innovation, said that compared with the BA.2 subtype, BA.4, BA.5 and BA.2.12.1 The plasma of three doses of new crown vaccine showed stronger antibody neutralization escape ability, especially the plasma of vaccinated BA.1 infection recovered patients showed significant neutralization escape ability.
The researchers also analyzed the immune escape mechanisms of the three new subtypes described above based on their key mutations.
The spike receptor binding domains of BA.4, BA.5 and BA.2.12.1 all carry the L452 mutation.
The L452 mutation has previously appeared in delta strains, but the early omicron subtype BA.1 does not contain the L452 mutation.
The researchers believe that multiple Omicron subtypes that have emerged recently carry the L452 mutation, which may be a response of the new coronavirus to the high level of population immunity caused by the "wave of infection" of Omicron.
Studies have shown that Omicron has been able to evolve certain mutations that specifically evade the humoral immunity elicited by BA.1 infection.
Scripps Research Institute virologist Christian Anderson of "Science" magazine said that although not yet know what new crown variants in the future there will be, but it is almost certain that they will increasingly have the ability to escape immune .
In future vaccine research and development work, "need to focus on expanding our immune system."