BREAKING COVID-19 News! Study Warns About Higher Reproduction Number of EG.5.1 Compared to XBB.1.16 And Raises Alarm On Humoral Immunity Issues!
Thailand Medical News Team Aug 09, 2023 1 year, 3 months, 1 week, 6 days, 4 hours, 30 minutes ago
COVID-19 News: In a startling revelation that has sent shockwaves through the global medical and scientific communities, researchers from the prestigious University of Tokyo in Japan have issued a dire warning about the newly identified SARS-CoV-2 subvariant known as EG.5.1 also known as the Eris variant that is currently spreading and rising in circulation in various geolocations across the world.
This variant, which has garnered significant attention due to its distinctive genetic makeup and rapid spread, has been found to possess a significantly higher effective reproduction number (Re) when compared to other notable subvariants, such as XBB.1.5 and XBB.1.16. Moreover, the study has unveiled troubling insights into the potential limitations of humoral immunity against EG.5.1, raising concerns about the effectiveness of breakthrough infection-induced immune responses.
As of July 2023, EG.5.1, alternatively referred to as XBB.1.9.2.5.1, has rapidly emerged in various countries, making headlines for its swift dissemination and potential impact on global health as covered in various
COVID-19 News coverages.
The World Health Organization (WHO) has taken notice of this variant, classifying it as a "variant under monitoring" as of July 19, 2023. The study, conducted by researchers at the University of Tokyo, aimed to shed light on the characteristics of EG.5.1 and its potential implications for the ongoing battle against the SARS-CoV-2 virus.
One of the most alarming findings of the study is the revelation that EG.5.1 exhibits a significantly higher effective reproduction number (Re) when compared to XBB.1.5, XBB.1.16, and its parental lineage, XBB.1.9.2. This critical metric, which indicates the average number of secondary infections generated by a single infected individual, is a key determinant of the virus's transmissibility and potential for rapid spread. The implications of this heightened Re are profound, suggesting that EG.5.1 has the potential to outcompete and supplant these XBB subvariants on a global scale in the near future.
However, the study also explored the complex interplay between EG.5.1 and the immune response induced by breakthrough infections (BTIs) of XBB subvariants.
Initial concerns had arisen that EG.5.1 might evade the antiviral effects of humoral immunity induced by XBB BTIs, potentially rendering the current approach less effective.
To address this concern, the researchers conducted a neutralization assay using XBB BTI sera to assess EG.5.1's susceptibility to immune responses. Surprisingly, the study found that the 50% neutralization titer (NT50) of XBB BTI sera against EG.5.1 was comparable to that of XBB.1.5/1.9.2 and XBB.1.16, indicating that EG.5.1's increased Re was not due to immune evasion from XBB BTIs.
Equally significant were the findings related to the efficiency of EG.5.1's antiviral humoral immunity induction. Previous research had shown that breakthrough infections of the Omicron variant did not efficiently induce antiviral humoral immunity against the variant itself. However, the study discovered a striking contrast with EG.5.1 and XBB subvariants. The NT50s of XBB1.5/1.9.2 and XBB.1.1
6 BTI sera against the variant were notably lower compared to the ancestral B.1.1 variant, suggesting that XBB BTIs struggle to induce effective antiviral humoral immunity against the newer XBB subvariants such as EG.5.1.
A pivotal aspect of the study delved into the origins and characteristics of the SARS-CoV-2 XBB lineage, a recombinant Omicron lineage that emerged in the summer of 2022. This lineage has given rise to several sublineages, with XBB.1.5 and XBB.1.16 being especially noteworthy due to their widespread dissemination.
EG.5.1, a subvariant of the XBB lineage, was found to bear unique genetic substitutions, including S:Q52H, S:F456L, and S:F486P. These genetic markers have contributed to its rapid spread in certain Asian and North American countries.
The implications of these findings have far-reaching consequences for the ongoing battle against the SARS-CoV-2 virus and the development of effective countermeasures.
Notably, the study has underscored potential challenges in inducing antiviral humoral immunity against EG.5.1 through breakthrough infections and further XBB vaccinations.
While the results do not suggest the ineffectiveness of XBB-containing vaccines, they do highlight the need for continued research and vigilance in understanding the intricate dynamics between emerging variants and the immune response.
In light of these findings, the medical community, public health agencies, and
policymakers are urged to closely monitor the trajectory of EG.5.1 and other emerging variants. The study serves as a wake-up call, emphasizing the urgency of maintaining robust surveillance, enhancing vaccination strategies, and further advancing our understanding of the complex interactions between viral evolution and the human immune system.
As researchers continue to unravel the mysteries of SARS-CoV-2 variants and their implications, it is evident that a collective and proactive effort is essential in order to effectively navigate the evolving landscape of the COVID-19 pandemic. The University of Tokyo's groundbreaking study sheds light on the intricate dance between viral genetics and immune responses, guiding us towards informed decisions and strategies in the ongoing fight against the global health crisis.
The study findings were published on a preprint server and are currently being peer reviewed.
https://www.biorxiv.org/content/10.1101/2023.08.08.552415v1
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