Omicron’s Newest BQ.1.1 Subvariant Shows Extraordinary Immune Evasion Potential Against Vaccine Sera

In a recent study published on bioRxiv* preprint server, researchers searched for immunological evidence of why the prevalence of BQ.1.1 has rapidly increased in areas where Omicron BA.5 was dominant in the United States (USA).

Study: Substantial neutralization escape by Omicron variant BQ.1.1 of SARS-CoV-2. Image Credit: Naeblys/Shutterstock

Background

Studies have shown that the frequency of Omicron BQ.1.1 cases is increasing rapidly in the United States and that Omicron BA.5 cases have fallen to less than half, whereas not so long ago , Omicron BA.5 was the dominant severe acute respiratory syndrome (SARS) coronavirus-2. -CoV-2). Thus, it is crucial to determine how BQ.1.1 eludes neutralizing antibodies (nAbs) induced by vaccination against coronavirus disease 2019 (COVID-19) and SARS-CoV-2 infection.

About the study

In the current study, researchers assessed nAb titers in 16 people who were vaccinated and boosted with the monovalent BNT162b2 mRNA vaccine in 2021. Next, they assessed nAb titers in 15 people who received the boosters of monovalent mRNA in 2022. Additionally, 18 recipient bivalent mRNA boosters, most of whom received three doses of vaccine, although some also received two or four doses of COVID-19 vaccine.

Study results

After monovalent BNT162b2 boost, the median nAb titers at WA1/2020, BA.5, BF.7, BA.2.75.2, and BQ.1.1 were 45, 695, 887, 595, 387, and 261, respectively. The authors noted that the median nAb titers against BQ.1.1 were much lower than the median nAb titers against WA1/2020 and BA.5 by factors of 175 and 3, respectively.

Compared to the 2021 uninfected cohort, most were likely infected in these cohorts, although documented rates of SARS-CoV-2 Omicron infections have been as low as 33%. Additionally, WA1/2020 and Omicron nAb titers were higher in both 2022 cohorts even before the booster. After the booster, their median NAb titers at WA1/2020, BA.5, BF.7, BA.2.75.2, and BQ.1.1 were 40,515, 3,693, 2,399, 883, and 508, respectively.

conclusion

The results of the study showed that compared to BA.5, BA.2.75.2 and BQ.1.1 were more efficient in evading nAbs induced by previous infection and vaccination. The effect was most pronounced for BQ.1.1, whose nAb titers were lower than BA.5 by a factor of seven in the study cohorts.

These results present an immunological explanation for the rapidly rising prevalence of BQ.1.1 in regions where BA.5 was dominant in the United States, which has implications for both vaccine and natural immunity. Furthermore, it puts into perspective how the presence of the R346T mutation in several new Omicron subvariants is likely a consequence of convergent evolution.

*Important Notice

bioRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice/health-related behaviors, or treated as established information.

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