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Jan 8 • 6 tweets • 2 min read
1/ Who gets severe COVID-19?
COVID-19 is a double-defect disease:
1. A defective early control of the virus by type I / III Interferons (IFN)
2. An impaired ability to control proinflammatory activities.
Only when both these checkpoints fail will critical disease develop.
2/ Interferons (IFN)
SARS-CoV-2 is a poor inducer of IFN:
Triggers limited & delayed type I / III IFN responses.
On the other hand, the virus is highly sensitive to IFN treatment similar to other coronaviruses.
Jan 8 • 5 tweets • 3 min read
Neutralizing antibodies are a good indicator of protection,
- not only against severe disease
- but also (if amounts are very high) against viral replication in the mucosa (with or without symptoms), thereby reducing transmission. #COVID19
On that day WHO was informed of cases of "pneumonia of unknown cause" in Wuhan, China.
Subsequently it was named COVID-19 caused by a novel coronavirus. Earlier we called the virus 2019-nCoV before finalizing the name SARS-COV-2.
Since then we have seen 2 to 5 waves in all countries caused by Variants of Concern (VoC), Variants of Interest (VoI) and Variants Under Monitoring (VUM)
Now our understanding of the disease and its management (including prevention) is much better.
Dec 24, 2021 • 39 tweets • 27 min read
The story of Omicron so far - virulence, severity, and hospitalisations across the globe.
🧵of tweets from reliable sources
1/ Who is more vulnerable to Omicron infection? @EricTopol
They outperform alternatives wrt filtration efficiency. Frontline clinicians & health care workers who engage in the highest risk procedures should be afforded the highest level of protection with NIOSH approved N95 respirators.
Oct 4, 2020 • 4 tweets • 2 min read
One article that covers ALL EVIDENCE on masks.
Association of American Physicians & Surgeons (Sept 26, 2020)
It says evidence is not much in favor of use of masks.
Masks may help when used correctly & along with other measures.
The article deals more with cloth masks used by general public in community settings. It's more of a compilation of literature, than a definitive guideline. Not a systematic review. However, many studies in this article DO say that 'masks can help reduce the virus transmission'.
Oct 2, 2020 • 4 tweets • 3 min read
Three genetic risk factors for COVID-19 complications:
 A gene cluster on chromosome 3 is a risk locus for #sarscov2 related respiratory failure.
Link: Nature, 30 Sept 2020 nature.com/articles/s4158…
 A new controlled study of >3000 hospitalized #COVID19 patients has confirmed it as the major genetic risk factor for severe #SARSCoV2 infection and hospitalization.
 This genetic risk is conferred by a genomic segment inherited from Neanderthals.
 By several criteria, the benchmark standard PCR fails when used in a surveillance regimen. nejm.org/doi/full/10.10…
 Many people whose infections are detected by PCR are no longer infectious at the time of detection.
 >50% infections identified by PCR had their CT values in the higher 30s, indicating low viral loads.
Should reduce a lot of #COVID19 anxiety in medical/ dental practice.
 LACK of #SARSCoV2 virus being CULTURED from surfaces, fomites, even in the hospital setting, pointing AGAINST this mode of transmission.
 Environmental contamination leading to SARS-COV-2 transmission is UNKIKELY to occur in real life conditions, provided that standard cleaning procedures & precautions are enforced.
Early decline of neutralizing Ab levels shouldn't be a concern. The key is at what levels Ab titers stabilize after natural infection/ vaccination. This represents the generation of long-lived plasma cells to protect against subsequent infection. #COVID19 jamanetwork.com/journals/jama/…
Individuals with mild or asymptomatic disease have shown robust memory T-cell responses months after COVID-19 infection.
However, it is unknown whether memory T cells in the absence of detectable circulating antibodies protect against SARS-CoV-2.
On day 1 of exposure, chances of RT PCR result coming negative are 100% (95% confidence interval [CI], 100%-100%).
Chances reduce as days pass.
On day 4 after exposure, chances of false negative decrease to 67% (CI, 27%-94%), but still big. #covid19 acc.org/latest-in-card…
Day 5: On the day of symptom onset (typically day 5), false-negative rate was 38% (CI, 18%-65%).
Day 8 (3 days after symptom onset)
chaces are the lowest- at 20% (CI, 12%-30%)
ACE2 receptors in multiple cell types act as entry points for #SARSCoV2
 Apart from respiratory, cardiovascular, GI-tract, renal-excretory and reproductive systems there is a significant ACE2 expression in brain/ CNS.
Cell & Mol Neurobiol 25, Aug 2020 link.springer.com/article/10.100…
 ACE2 receptor expression detected in multiple brain regions. Highest levels detected in pons / medulla oblongata - respiratory centers of brain. This may in part explain the respiratory distress.