Plasma samples from individuals who had received three doses of CoronaVac and had a BA.1, BA.5, or BF.7 breakthrough infection showed a substantial decrease in plasma 50% neutralisation titre against XBB.1 and XBB.1.5 compared with that against B.1 variant. Surface plasmon resonance sensorgrams measuring the hACE2-binding affinity of SARS-CoV-2 BQ.1.1, XBB and XBB.1, and XBB.1.5 receptor-binding domain. Compared with XBB.1, XBB.1.5 had similar evasion against therapeutic mAbs ; Evusheld and bebtelovimab did not neutralise XBB.1.5 pseudovirus.

COVID-19–associated mortality among persons aged ≥60 years exceeded 80% of total COVID-19 mortality in 2020 and 2021 across all income groups; however, the median reported completed primary series coverage among older adults in 2022 was 76%, substantially below the WHO goal, especially in middle- and low-income countries. COVID-19 mortality rates increased markedly in older age groups: persons aged ≥60 years accounted for 80% of COVID-19–associated deaths reported through weekly detailed surveillance and 82% of estimated deaths from the WHO excess mortality model.

We next investigated the virological features of XBB.1.5. However, XBB.1.5 without S:Y144del exhibited a lower Re compared with the original XBB.1.5. Lentivirus-based pseudovirus assays showed that the 144Y insertion increased the infectivity of XBB.1 but did not affect the infectivity of XBB.1.5. Our data suggest that these virological features result in greater transmissibility.

Immune imprinting was first described in the context of influenza as “original antigenic sin” by Thomas Francis Jr in 1960.1TF Jr, On the Doctrine of Original Antigenic Sin.Google Scholar Influenza imprinting might nudge the immune response towards conserved regions of currently circulating influenza virus strains, rather than the most immunogenic region of the dominant strain of the future influenza epidemics.

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The antiviral activity of these NBCoVs was evaluated in two cell lines, 293T-ACE2 and A549-AT cells, infected with SARS-CoV-2 WA-1 pseudovirus pretreated with increasing concentrations of NBCoV. As before, NBCoV63 retained good anti-CoV activity against both, but NBCoV 35–37 had higher IC50 values ​​for Calu-3 cells over other cell lines. NBCoV was also evaluated for activity against SARS-CoV and MERS-CoV pseudoviruses. Again, NBCoV63 was the most potent inhibitor against SARS-CoV and MERS-CoV.

As earlier, NBCoV63 retained its excellent anti-CoV activity against both, whereas NBCoVs 35 – 37 had higher IC50 values in Calu-3 cells than in other cell lines. The NBCoVs were also evaluated for activity against pseudoviruses of SARS-CoV and MERS-CoV. Again, NBCoV63 was the most potent inhibitor against SARS-CoV and MERS-CoV. The team noted that NBCoV63 also blocked SARS-CoV-2-mediated cell-cell fusion, indicating its ability to disrupt SARS-CoV-2 spike-ACE2 binding and cell-cell fusion.

A recent study found that the bivalent COVID-19 boosters produce neutralizing antibodies against Omicron subvariant XBB. Here's what experts want you to know about the new bivalent COVID boosters and XBB.1.5. Are Bivalent Boosters Better than Original Vaccines? The updated bivalent COVID booster is expected to provide you with better protection against the Omicron subvariant XBB.1.5.

The immune system responds more strongly to the strain of a virus that it first met, weakening response to other strains. Their immune systems responded to a new circulating strain by producing antibodies tailored to their first flu encounter. Furthermore, even exposure to Omicron itself doesn’t seem to help update the imprinted response of people previously infected with an older strain, which might explain why they can be reinfected.

Well, perhaps Dr Kerryn Phelps and her wife, in their disclosure just before Christmas 2022 admitting that they had suffered severe side effects from their Covid vaccines, would agree. But why are we no longer seeing the daily media parade at 11 am from Health Ministers, regulators, and fringe-dwelling health bureaucrats with little to no clinical experience with Covid addressing the serious adverse effects and deaths from vaccines? The manufacturer, doctors, health bureaucrats, and/or politicians? Perhaps this is why the burden of proof has shifted from the manufacturer to the consumer.