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Vipin M. Vashishtha

@vipintukur

Jan 26

Is #Omicron more likely than #Delta to cause infections in vaccinated persons?

The study found that the positivity rate among unvaccinated persons was higher for Delta (5.2%) than Omicron (4.5%).

They found similar results in persons who received a single vaccine dose 1/

Conversely, the Omicron had higher positivity rates than Delta among those who received two doses within 5 months (Omicron = 4.7% vs. Delta = 2.6%), two doses >5 months ago (4.2% vs. 2.9%), & three vaccine doses (2.2% vs. 0.9%). 2/

Omicron positivity rates in persons receiving one or two vaccine doses were not significantly lower than unvaccinated persons but were 49.7% lower after three doses. 3/

Read 7 tweets

Vipin M. Vashishtha

@vipintukur

Jan 26

#Omicron features 50 mutations, with 15 mutations in the #RBD of the spike protein, which binds to the human #ACE2 for viral entry. However, it is not completely understood how these mutations alter the interaction and binding strength between the Omicron RBD and ACE2 1/

A new study by adopting a combined steered molecular dynamics (SMD) simulation and experimental microscale thermophoresis (MST) approach tried to quantify the interaction between Omicron RBD & ACE2. 2/

And what did they find?

Omicron brings an enhanced RBD-ACE2 interface through N501Y, Q493K/R, & T478K mutations; the changes further lead to unique interaction patterns, reminiscing the features of previously dominated variants, Alpha (N501Y) & Delta (L452R and T478K). 3/

Read 5 tweets

Vipin M. Vashishtha

@vipintukur

Jan 26

People are calling #Omicron a natural (live attenuated) vaccine. They say it’s emergence is itself a proof that the virus is receding to a milder form.
And getting Omicron infection is a sure shot way to get protection against all the VOCs!!👇. 1/

But we must remember that, “Every infection is not one step closer to the end, it's one step closer to the next variant.”
The only way to end this cycle is to stop giving it chances to replicate! 2/

theatlantic.com/science/archiv…

@_DavidGlassman

“Calling the #Omicron “mild” was an unforced error that an understanding of lagged time series would have prevented.”

Omicron is not mild. 🦠 do not need to evolve to be less deadly. And endemicity has nothing to do with mildness @_DavidGlassman 3/

dglassman.medium.com/omicron-was-ne…

Read 4 tweets

Vipin M. Vashishtha

@vipintukur

Jan 25

Why #Omicron VOC has predilection for upper airways? Why 🫁 are comparatively spared in Omicron infection?

1/

Recent works revealed major changes in the #Omicron biological properties (the impairment of cell surface entry & syncytia formation) compared to earlier VoCs. These major changes could be explained, at least in part, by the mutations #N764K and/or #N856K in S2 subunit.

These mutations were not previously detected in other VoCs. #N764K and #N856K generate two potential cleavage sites for SKI-1/S1P serine protease, known to cleave viral envelope glycoproteins. 3/

Read 6 tweets

Vipin M. Vashishtha

@vipintukur

Jan 25

The word ‘endemic’ has become one of the most misused of the pandemic.

An endemic infection is one in which overall rates are static — not rising, not falling. More precisely, it means that the proportion of people who can get sick balances out the ‘Ro’ of the virus. 1/

Assuming a population in which everyone could get sick. Yes, common colds are endemic. So are Lassa fever, malaria and polio. So was smallpox, until vaccines stamped it out. 2/

In other words, a disease can be endemic and both widespread and deadly. Malaria killed more than 600,000 people in 2020. Ten million fell ill with TB that same year and 1.5 million died. 3/

Read 14 tweets

Vipin M. Vashishtha

@vipintukur

Jan 21

This study from #Singapore compares the immune characteristics of 55 patients with vaccine breakthrough #SARSCoV2 infection and 86 uninfected vaccinated close contacts. 1/

Antibody levels, including neutralizing antibodies, were similar in vaccine breakthrough patients and close contacts. 2/

Memory B cell levels, as assessed by B cell ELISpot, were lower in vaccine breakthrough patients than close contacts. 3/

Read 7 tweets

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