Fourth vaccine shot 'not good enough' against #Omicron in #Israel!
A study conducted at Sheba Medical Center indicates a fourth shot of the Pfizer Covid vaccine provides insufficient protection against the Omicron variant!
The researchers though find an increase in antibodies, higher than after the 3rd dose. However, many were found infected with Omicron who received the 4th dose.
Let’s see how Israel, a hyper-vaxxed country, and India, a country with modest coverage of 2-doses of Covid vaccines performing 👇
And here is the comparison in deaths (per million). Though there are many factors that may be responsible for the lower mortality in Asian countries than the west👇
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1-The dysregulation of innate and adaptive immunity has been recognized to play a critical role in the clinical outcome of COVID-19 patients. 1/
2-Severe evolution of COVID is thought to be driven by hyperactivated innate immunity in addition to adaptive immune defects resulting in lymphopenia & neutrophils/lymphocytes imbalance
3-A deficient IFN response has also been shown to favor or result from SARS2 infection 2/
These immunological dysregulations are thus underlying hyper-immune reactions such as the “cytokine storm” syndrome, MIS-C, dysregulation of coagulation, as well as neurological & various other manifestations 3/
#COVID19 breakthrough infection after #CoronaVac inactivated vaccine induced robust antibody responses & cross-neutralization of #SARS2 variants, but less immunity against #Omicron
1/
Binding antibody levels in sera from patients with breakthrough infection (BI) were significantly higher than those in individuals who had received AstraZeneca Vaccine as a third vaccination. 2:
However, neutralizing activities against wild-type and variants including Alpha, Beta, & Delta were comparable in patients with BI & individuals who received a 3rd vaccination with AZ vax, which activities are exceeding 90%. 3/
A new modelling study on the value of vaccine boosters to mitigate the global impact of #Omicron
By fitting an immunological model to population-level vaccine effectiveness (VE) data, NAb titres for Omicron are reduced by 3.9 fold compared to the Delta variant 1/
Under this model, it is predicted that 90 days after boosting with the Pfizer-BioNTech vaccine, efficacy against severe disease (admission to hospital) declines to 95.9% against the Delta & 78.8% against the Omicron 2/
Integrating this immunological model within a model of SARS2 transmission, the size of the Omicron wave will depend on the degree of past exposure to infection across the population, w/ relatively small Omicron waves in countries that previously experienced a large Delta wave 3/
The current narrative is, “Covid vaccines prevent severe disease & deaths.”This is going back on the stated primary endpoint “prevention of symptomatic disease.”
Why is it important to avoid symptomatic disease even during the #Omicron surge? 1/
Even infection is worrisome: may damage/destroy T cells! According to T cells expert @fitterhappierAJ “CD95-mediated [T cell] differentiation & death may be advancing T cells to greater effector acquisition, fewer numbers, & immune dysregulation.” 2/
Delta & Omicron strains are the most globally relevant VOCs. While individuals infected with Delta are at risk to develop severe lung disease, Omicron infection causes less severe disease, mostly URT symptoms. 1/
The question arises whether rampant spread of #Omicron could lead to mass immunization, accelerating the end of the pandemic. 2/
A new study shows that infection with Delta, but not Omicron, induces broad immunity in mice. While sera from Omicron-infected mice only neutralize Omicron, sera from Delta-infected mice are broadly effective against Delta and other VOCs, including Omicron. 3/
The current events have ‘forced’ me to do a quick, random analysis of global Covid Vaccination (may not be perfect). A short thread….👇 1/
1-Covid vaccines are not providing good protection against infection including ‘symptomatic disease’: the primary endpoint of their efficacy trials
2-They failed to provide reasonable durability of immune response, more so ag the last two global VOC. 2/
3-Though high NAb titers are no guarantee for protection against infection, for a highly immune evading variant like Omicron, one needs several folds(>30-40 folds) higher titers than other variants for protection