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Vipin M. Vashishtha Profile picture
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Feb 8 • 5 tweets • 3 min read
#Reinfection in the #UK:

Reinfections for people with Prior Covid were rare until #Omicron arrived 1/

assets.publishing.service.gov.uk/government/upl… Image
A newly dominant variant can reinfect only those who got infected with prior variants, but same-variant reinfection is extremely unlikely. This pattern seems to hold for ancestral variants & Delta 2/

Image
A new @NatureMicrobial report: Despite a marked ⬇️ in NAbs over time, NAb responses persist for up to 480 d in most convalescents of symptomatic COVID19, whereas a high rate of undetectable NAb responses was found in those w/ asymptomatic infections 3/

nature.com/articles/s4156… Image
However, we shouldn’t forget the susceptibility to #Omicron infections in people with Prior Covid, w/out vaccination, is at least 16-fold that of prior variants due to the immune evading potential of Omicron. 4/
Another recent study finds that the people who previously had #COVID, antibodies were present in 99.9% of them up to nearly 2 years after infection. 5/

hopkinsmedicine.org/news/newsroom/…

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More from @vipintukur

Vipin M. Vashishtha Profile picture
Feb 9
Antibody & Memory B-cell immunity in a heterogeneously #SARS2 infected & vaccinated population from #Mexico where five different vaccines have been deployed to populations with high SARS2 incidence. 1/
Levels of antibodies that bound a stabilized prefusion spike trimer, neutralizing antibody titers & memory B-cell expansion correlated with each other across vaccine platforms. 2/ ImageImage
Neutralizing antibody titers against SARS-CoV-2 variants vary between different vaccines: different vaccines elicited variable levels of B-cell immunity, & the majority of recipients had undetectable neutralizing activity against the recently emergent omicron variant. 3/ Image
Read 5 tweets
Vipin M. Vashishtha Profile picture
Feb 9
NIAID/NIH researchers developed a replicating RNA vaccine expressing the Omicron (B.1.1.529) spike. They conducted animal studies for the following objectives:

1-How does pre-existing immunity affect the antibody response to an omicron-targeted booster vaccine (in mice) 1/
In mice, their main objective was to evaluate the effect of pre-existing immunity on the antibody response to the B.1.1.529-targeted vaccine (using an influenza repRNA vaccine to control for background immunity to the repRNA backbone) 👇 2/ Image
2-In hamsters, the main objective was to evaluate the protective efficacy of a single-dose B.1.1.529 repRNA vaccine relative to the ancestral A.1 repRNA vaccine following infection with B.1.1.529 virus as shown in the study design 👇 3/ Image
Read 12 tweets
Vipin M. Vashishtha Profile picture
Feb 8
In a new study, the researchers develop a panel of mRNA-LNP-based vaccines using the RBD of #Omicron & #Delta, which are dominant in the current wave of COVID-19. 1/
In addition to the Omicron- & Delta-specific vaccines, the panel also includes a “#Hybrid” vaccine that uses the RBD containing all 16 point-mutations shown in Omicron & Delta RBD, as well as a #bivalent vaccine composed of both Omicron and Delta RBD-LNP in half dose. 2/
Interestingly, both Omicron-specific & Hybrid RBD-LNP elicited extremely high titer of NAbs against Omicron itself, but few to none NAbs against other SARS-CoV-2 variants. 3/ Image
Read 6 tweets
Vipin M. Vashishtha Profile picture
Feb 5
The rise of #SARS2 variants & evidence of immunological interference (like OAS & weakened T-cell immunity) underscore the need for preemptive, next-gen vaccines that confer broad protection ag Covid

My piece in @theWireScience👇 @fitterhappierAJ

science.thewire.in/health/omicron…
What is common between Denmark, Israel, Austria, France, Switzerland, the UK, and the US? They all suffered an unprecedented severe wave of Omicron despite having some of the highest vaccination rates in the world. 2/ @1amnerd @thewire_in
@1amnerd @thewire_in Most of the Covid19 vaccines are based on spike-protein of SARS2. They have worked reasonably well so far. However, with the advent of #Omicron, one of the most mutated variants has exposed the limitations of these vaccines, particularly their ability to prevent infections 3/
Read 34 tweets
Vipin M. Vashishtha Profile picture
Feb 3
Why did triple vaxxed #Israel recently purchase enough @Novavax vaccine shots to jab their entire population?

Because this is the one vaccine that holds promise to work ag diff future variants!

But, this is a mystery why one of the best Covid vax is still sitting on bench!
1/
Just sharing few key points of a great analysis of this vaccine by @michaelzlin

A recent study by Novavax suggests it may be able to provide broader protection across variants than other vaccines so far. That is a great news, if true! 2/

medrxiv.org/content/10.110…
Besides a potentially broader antibody response, Novavax has the advantage of being stable in the refrigerator, so should be easier to distribute as well
3/
Read 11 tweets
Vipin M. Vashishtha Profile picture
Feb 3
Some info on #Omicron’s sublineages:

1-BA.1 & BA.2 are the 1st generation sub-lineage of the Omicron variant whereas BA.1.1 is the 2nd generation sub-lineage of the Omicron variant

2-BA.1.1 sublineage is BA.1 + R346K that is more escape because site 346 is major antigenic site
News from #India:

BA.2 lineage eclipses BA.1 to become predominant in #Gujarat

BA.2 accounts for 45.7% of 448 samples sequenced in Jan in #Gujarat . BA.1 accounts for 28%

Researchers say mutations in BA.2 as seen in #India appear diff than that seen in other countries. 2/
In #Pune, of all patients with severe disease who were successfully sequenced, BA 1.1 was overwhelmingly found.

In #Gujarat, many samples earlier classified as BA.1 have been reclassified as BA.1.1, retrospectively. 3/
Read 5 tweets

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