Bivalent coronavirus vaccines, available since the fall, that combat the Omicron variant, are also effective against the new ChBB.1.5 subvariant, or Kraken, according to US scientific research published in the New England Journal of Medicine.

A new study co-authored by 17 professors of medicine, mostly from the Emory University School of Medicine in Atlanta, USA, found significantly higher immunity to Kraken in those who were vaccinated with an updated dose of Pfizer’s or Moderna’s Omicron vaccine. compared to those who received one or two doses of the original monovalent vaccine that fought the original coronavirus strain identified in 2019 in Wuhan, China.

Sub-variant XBB.1.5, or “Kraken” as it is known, is growing rapidly in the US, gradually spreading to other regions of the Northern Hemisphere. On Thursday, it was announced its first detection in Russia after several other European countries.

According to a new study, those who received what is known as a “complex” vaccination, i.e. two doses of the original monovalent mRNA vaccine from Pfizer or Moderna, have very limited immunity against the original strains of Omicron (BA1, BA4 and BA5) and almost none against its newer sub-variants. , i.e. BA.2.75.2, BQ.1.1 and XBB, which seem to have dominated the US in recent months, bypassing vaccine immunity and antibodies from previous disease.

In particular, the number of geometric mean titers (GMT) of neutralizing antibodies that appeared in those who received two doses of the original vaccine was 2352 against the original strain of coronavirus, 408 against Omicron 1, 250 against Omicron 5, 98 against AD. 2.75.2, 73 vs. BQ.1.1 and 37 vs. XBB.

At the same time, the average value of GT antibodies in those who received the updated vaccine was 2481 against the original strain, 618 against Omicron 1, 576 against Omicron 5, 201 against BA.2.75.2, 112 against BQ.1.1 and 96 against BBB . This means at least two and a half times greater immunity to Kraken in those who received a double vaccine than in those who were vaccinated with only two doses of the original vaccine.

Scientists supporting the study add that the results are consistent with recent observations of people with Omicron infection demonstrating increased body neutralizing activity against Omicron sub-variants.

As Neil Mabbott, Chair of Infectious Diseases at the University of Edinburgh in the UK, points out in his article, both this study and data from previous studies show that vaccination with a bivalent vaccine designed to treat both BA4 and BA5 strains would be effective against both existing sub-options such as “Kraken”, and against others that will appear in the future.

Source: New England Journal of Medicine, The Conversation.