BA.2.12.1 is ready to dominate the U.S., raising concerns for future vaccines

Enlargement / A health worker organizes nucleic acid samples on May 3, 2022 at a temporary nucleic acid test site in Beijing, China.

According to the latest estimates released by the Centers for Disease Control and Prevention on Tuesday, the micron subvariant BA.2.12.1 is ready to dominate the U.S., currently accounting for approximately 36.5 percent of U.S. SARS-CoV-2 cases.

The Subvariant Rise is the latest rapid turn of the Omicron subvariants, from the BA.1 Omicron Subvarian in January to the current blow of the BA.2 Subvariant, which dominated in March. As before, the reason for the usurpation of the virus continues to develop the advantages of micron subvariants: BA.2.12.1 has a transmission advantage over BA.2, which has a significant advantage over delta over BA.1. .

The recent administration of BA.2.12.1 raises concerns about another wave of infections and raises questions about how effective future omicron-specific vaccines may be against symptomatic infections.

So far, the good news is that current vaccines still provide strong protection against severe COVID-19 and do not appear to cause more severe disease than BA.2.12.1 BA.1 or BA.2, but the CDC and other health experts are actively monitoring this. However, the subvarian appears to be able to avoid immune protection, especially from previous BA.1 infections.

To flee

According to preliminary data posted on the Internet on Monday, researchers in Beijing found that BA.2.12.1 showed “avoidance of strong neutralization” against antibodies in vaccinated people, including those with BA.1 infection. Participants in the study were vaccinated with Sinovac’s CoronaVac vaccine, an inactivated whole-body antiviral vaccine that was about 50 percent effective in the first observational study in Brazil. (mRNA-based vaccines have been shown to be around 95 percent effective in initial clinical trials.)

The researchers looked at neutralizing antibodies in 50 people who received three doses of CoronaVac and recovered from a BA.1 infection. Comparing the levels of neutralizing antibodies against a number of coronavirus variants, the researchers found that the level of neutralizing antibodies against BA.2 was approximately 1.86 times lower than that of BA.1. However, the situation worsened as the researchers switched to the new subvariants: the level of neutralizing antibodies was 3.73 times lower for BA.2.12.1 than for BA.1, and eight times lower for BA.4 and BA.5.

The latest find is similar to preliminary data from South Africa, Ars said on Monday. There, the researchers found that neutralized antibody levels were 7.6 times lower and 7.5 times lower than BA.1 and BA.5, respectively, in people who recovered from unvaccinated BA.1 infection. Although vaccination with Pfizer / BioNTech or J&J vaccine narrowed the gap in neutralizing antibody levels, the researchers still found a loss of protection: the levels of neutralizing antibodies against BA.4 and BA.5 were 3.6 times lower and 2.6 times lower, respectively. With BA.1.

Together, these data suggest that new omicron subvariants are more likely to be re-infected, especially those who have not been vaccinated or who have not been vaccinated. This could lead to more waves of infections in the U.S. and around the world, but experts do not expect another big wave like BA.1 to appear in January.

worries

It also raises concerns about the design of second-generation vaccines – some of which may be at least partially targeted at BA.1. For example, last month, Modernna announced that a bivalent vaccine — targeting two versions of the virus with a single blow — would be a winning strategy to provide broader, longer-lasting protection.

“Our latest bivalent amplifier candidate, mRNA-1273.214, currently combines an authorized Modern COVID-19 amplifier with us. [BA.1] A special booster candidate for the omicron remains our main contender for the Northern Hemisphere in the fall of 2022, ”Moderna CEO Stefan Bansel said in a statement at the time.

However, new data suggest that BA.1-based vaccines provide poor protection against BA.2, BA.4, BA.5, and other omicron subvalants.

“Unlike when the omicron first appeared, now the subliny of the omicron have begun to target humoral immunity. [antibodies and other adaptive responses] Humor caused by omicron itself, including post-vaccination omicron infection, the authors of a new study from Beijing write. “This poses a major challenge to the establishment of immune defenses” and “suggests that a vaccine based on omicron BA.1 may be possible.” cannot be an ideal antigen to provide a broad-spectrum protection against emerging omicron subline. “

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