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
4-Frequent boosting is not a sound public health policy. Current vaccines are developed on backbone of the spike that doesn’t match with the Omicron’s spike!

5-Nevertheless, 2 doses of vaccines based on the spike of D614G are providing good protection against severe disease.
6-The key public health role of vaccines is prevention of disease what other vaccines like measles, rubella, HepA & B, etc have done/are doing.
7-Prevention of hospitalisation & deaths is the least ambitious goal of vaccines!! Vaccines have eliminated few VPDs like smallpox, polio, measles, etc. And this was not the *primary* objective of the early Covid19 vaccine trials.
9-For prevention of deaths, we have other tools like the antivirals & other therapeutics.

10-But Coronaviruses’ case is different. We could never succeed in developing an effective vaccine against any old CoV: HCCCoVs, SARS, or MERS…..
11-So, developing >15 licensed products within a span of 15 months was a feat that must be celebrated!!
12-So, where do we go from here? We are still not at the driving seat. The virus is still ahead of us, dictating the terms, and still evolving. The main target of the 🦠 is still to achieve higher transmissibility through immune evasion (selection pressure)
13-On the vaccines front, we need to urgently revise our formulations. All the three aspects need to be bolstered: innate immunity (BCG like ag for trained immunity), mucosal immunity (need intranasal vax), and more effective & specific humoral responses.
14-To achieve the last, we need to have a ‘variant-specific’ or ‘multiple-epitopic/antigen’ vaccines. A ‘spike-only’ approach has probably not worked. Need to exploit more conserved epitopes located at other parts of the virus.
15-Vaccine developers must keep their promise: “will be able to tweak the vaccine shots matching a new variant within weeks”. Let’s commercial ‘considerations’ take a back seat to the scientific needs!
16-So, what do we do? Should focus on ‘VaccinePlus’ approach till the pandemic dies it’s own. After all, in all the past pandemics either vaccines were not available or played only a bystander role!
17-Ultimately, a universal, pan-sarbecovirus vaccine will be required.
But, what about the viability of all these new products? For how long will they be needed? In the post-pandemic era too? Yes, may be. Till the *intimate* human-animal interaction comes to a halt

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More from @vipintukur

Jan 19
📌 A must-read article, the missing link?

What we know so far?

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/
Read 25 tweets
Jan 19
A new study from #Thailand

#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/ Image
Read 4 tweets
Jan 19
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/
Read 7 tweets
Jan 19
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/

frontiersin.org/articles/10.33… Image
T cells are decreased and exhausted in patients with COVID-19. Cytokines such as IL-10, IL-6, and TNF-α might be involved in T cell reduction. 3/

frontiersin.org/articles/10.33… Image
Read 6 tweets
Jan 18
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/ Image
Read 20 tweets
Jan 18
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!

timesofisrael.com/liveblog_entry…
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 👇
Read 4 tweets

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