1/📌The UK #SARSCoV2 variant reported to be 70% more transmissible harbors a set of mutations in the Spike protein––the part of the virus that touches the human ACE2 receptor and allows the virus entry into our cells. One mutation, N501Y, allows Spike to bind ACE2 more tightly🧵
2/Another mutation, P681H, is near Spike's "Furin cleavage site" Unclear what the mutation does, but the location is significant because it's where enzymes "process" Spike, helping virus infect airway cells & enable efficient human-to-human transmission: rb.gy/sp0p34
3/these mutations are accumulating in the backdrop of another mutation, D614G, which has become dominant, globally, and has enhanced infectivity and replication fitness. It's even been shown, experimentally, to transmit faster through droplets & aerosols in hamsters.
4/In that experiment, naive hamsters caught the virus faster from hamsters that carried the D614G variant, vs hamsters that carried the original (WT) strain. So one would also expect earlier transmission of D614G in humans. biorxiv.org/content/10.110…
5/These are just a few of the many mutations this virus is accumulating. Every time it replicates, we give it the opportunity to mutate. And if those mutations render drugs and vaccines ineffective, which is possible, we'll be in a lot more trouble. virological.org/t/preliminary-…
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1/Great to be on @Mitch_Seattle to discuss the difference between the Pfizer, Moderna, and other vaccines💉and why we need high coverage in order to stop the chain of transmission🧵
2/The #Moderna vaccine, just like Pfizer/BioNTech, is a messenger RNA vaccine. #SARSCoV2 is covered w/Spike proteins that it grabs human cells with. The vaccine consists of small genetic material "messenger RNA" that instructs the human cell to make a part of the Spike protein
3/The mRNA is encased in a formulation of fatty material that helps it get inside our cells. There, it's "translated" into a piece of the Spike protein which activates our immune system to make antibodies & T cells so when we're exposed to the live virus, we can clear it.
📌1/CDC Report on Vietnam's🇻🇳Incredible Tracing/Quarantine Program: after outbreak in major Hanoi Hospital, entire 7,664-persons staff quarantined. Contact tracing in the community resulted in an additional 52,239 people being quarantined. After 3 weeks, outbreak was contained🧵
2/They didn't just quarantine close contacts of infected, but all hospital visitors & their close contacts (F2s) were provided quarantine support: room and board. Contacts of F2s (F3s) & Contacts of F3s (F4s) were even asked to self-isolate: wwwnc.cdc.gov/eid/article/27…
3/Aggressive tracing/quarantine in Vietnam isn't unique to this outbreak. As @findingsen writes, once case is identified, all contacts in prior week are identified and quarantined. Those individuals' contacts are identified and asked to self-isolate. globalasia.org/v15no3/cover/v…:
1/Suspected #SARSCoV2 reinfection in Peru🇵🇪: symptomatic 42yr old tested positive in June, but did not develop pneumonia (Row A👇). She improved, symptoms resolved. Then in October, she presented w/symptoms again, tested positive, this time had lung lesions w/pneumonia (Row B)🧵
2/case highlights there are far more reinfections than confirmed. Bar to establish reinfection is high: requires genetic sequencing of viruses to rule out single continuing infection but only small # of samples are sequenced/stored for future purposes like confirming reinfection.
3/For instance, at the GISAID international database of SARS-CoV-2 genetic sequences, there are only 385 virus🧬sequences from Peru, but the country has reported about 1 Million cases, so only 0.04% of cases have been sequenced.
1/📌SARS-CoV-2 in aerosols: from dispersion in air, to inhalation and disease: (a) while large drops (green) are ballistically and fall, smaller ones (red) can remain buoyant; (b) Droplets evaporate to form aerosols, reducing to just biopolymers and virus particles🧵
2/Larger aerosols deposit in upper throat, nose, & tracheobronchial region of the lung. Medium-sized aerosols mostly deposit in small airways further down. The really small aerosols <1 μm can penetrate all the way to the alveoli - the basic units for gas exchange.
3/In contrast to other mode of transmission where virus hits nasal cavity and then finds its way into lungs, aerosols can directly reach alveolar region and attack alveolar cells that produce Pulmonary Surfactant. PS is needed to lower surface tension & prevent alveoli collapse
1/📌COVID-19 neurological challenges: while respiratory problems receive most attention, nearly 10-35% survivors suffer disabling, persistent neurological symptoms. Patients w/altered mental health hospitalized 3X times longer; 2/3 unable to manage daily activities at discharge🧵
2/Underlying causes are complex. Low oxygen; metabolic irregularities. Inflammatory response in the brain—activation of microglia & cytotoxic T cells—and other signs of neuropathy have also been observed.
3/Loss of smell/taste: 40-60% of patients develop loss of smell; ~90% have alteration of smell. Many recover sense of smell, others have more severe cases, possibly permanent loss of smell. Virus invades cells in vicinity of olfactory nerve; unclear if it directly invades nerve
1/The #AstraZeneca vaccine is a version of an adenovirus (common cold virus) that delivers instructions to our cells to make the Spike protein of the coronavirus. That way our immune system is "trained" so when it encounters #SARSCoV2, it can mount an efficient response🧵
2/#SARSCoV2 is covered w/Spike proteins that help the virus grab human cells. To make the vaccine, researchers first isolated the gene that is responsible for making the Spike protein. They 'snipped' it from the rest of the genetic material of the coronavirus.
3/They then needed a delivery vehicle to get the Spike gene into our cells. So they took an adenovirus that normally infects chimpanzees, and genetically altered it so it can no longer replicate or cause disease. They then added the Spike gene to the adenovirus vector.