The biology of coronavirus COVID-19 - including research and treatments

Editorial: Sex differences in antiviral immunity in SARS‐CoV‐2 infection: mitochondria and mitomiR come into view
Mitochondria are multifaceted organelles representing the “powerhouse of cells” for their function as bioenergetics and biosynthetic hubs. In addition, they play an essential role in the regulation of innate and adaptive immune responses, including host defenses against viruses, as well as in inflammatory responses 1. This peculiar role of mitochondria is principally due to the activation of adaptor mitochondrial proteins, known as mitochondrial antiviral signaling (MAVS) proteins. MAVS sense viral RNA and trigger the activation of the transcription factor NF‐kB or IFN pathways and autophagy, in order to clear the infection and avoid excessive inflammation, respectively1.
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Open access, https://onlinelibrary.wiley.com/doi/10.1111/apha.13571
 
Modeling COVID-19 scenarios for the United States

We use COVID-19 case and mortality data from 1 February 2020 to 21 September 2020 and a deterministic SEIR (susceptible, exposed, infectious and recovered) compartmental framework to model possible trajectories of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and the effects of non-pharmaceutical interventions in the United States at the state level from 22 September 2020 through 28 February 2021. Using this SEIR model, and projections of critical driving covariates (pneumonia seasonality, mobility, testing rates and mask use per capita), we assessed scenarios of social distancing mandates and levels of mask use. Projections of current non-pharmaceutical intervention strategies by state—with social distancing mandates reinstated when a threshold of 8 deaths per million population is exceeded (reference scenario)—suggest that, cumulatively, 511,373 (469,578–578,347) lives could be lost to COVID-19 across the United States by 28 February 2021. We find that achieving universal mask use (95% mask use in public) could be sufficient to ameliorate the worst effects of epidemic resurgences in many states. Universal mask use could save an additional 129,574 (85,284–170,867) lives from September 22, 2020 through the end of February 2021, or an additional 95,814 (60,731–133,077) lives assuming a lesser adoption of mask wearing (85%), when compared to the reference scenario.
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Open access, https://www.nature.com/articles/s41591-020-1132-9
 
Largest COVID-19 contact tracing study to date finds children key to spread, evidence of superspreaders
A study of more than a half-million people in India who were exposed to the novel coronavirus SARS-CoV-2 suggests that the virus’ continued spread is driven by only a small percentage of those who become infected.

Furthermore, children and young adults were found to be potentially much more important to transmitting the virus — especially within households — than previous studies have identified, according to a paper by researchers from the United States and India published Sept. 30 in the journal Science.

Researchers from the Princeton Environmental Institute (PEI), Johns Hopkins University and the University of California, Berkeley, worked with public health officials in the southeast Indian states of Tamil Nadu and Andhra Pradesh to track the infection pathways and mortality rate of 575,071 individuals who were exposed to 84,965 confirmed cases of COVID-19, the disease caused by SARS-CoV-2. It is the largest contact tracing study — which is the process of identifying people who came into contact with an infected person — conducted in the world for any disease.

Lead researcher Ramanan Laxminarayan, a senior research scholar in PEI, said that the paper is the first large study to capture the extraordinary extent to which SARS-CoV-2 hinges on “superspreading,” in which a small percentage of the infected population passes the virus on to more people. The researchers found that 71% of infected individuals did not infect any of their contacts, while a mere 8% of infected individuals accounted for 60% of new infections.
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https://www.princeton.edu/news/2020...study-date-finds-children-key-spread-evidence
 
"Lead researcher Ramanan Laxminarayan, a senior research scholar in PEI, said that the paper is the first large study to capture the extraordinary extent to which SARS-CoV-2 hinges on “superspreading,” in which a small percentage of the infected population passes the virus on to more people. The researchers found that 71% of infected individuals did not infect any of their contacts, while a mere 8% of infected individuals accounted for 60% of new infections."

That's extraordinary if it's true. I was aware that there are differences in the extent to which individuals infect (or don't infect) others, but I didn't realise it could differ quite that much!
 
Moved post

Covid: Antibodies 'fall rapidly after infection'
"Immunity is waning quite rapidly, we're only three months after our first [round of tests] and we're already showing a 26% decline in antibodies," said Prof Helen Ward, one of the researchers.
https://www.bbc.co.uk/news/health-54696873

Press release
https://www.imperial.ac.uk/news/207333/coronavirus-antibody-prevalence-falling-england-react/

Declining prevalence of antibody positivity to SARS-CoV-2: a community study of 365,000 adults (preprint)
https://www.imperial.ac.uk/media/im...-innovation/MEDRXIV-2020-219725v1-Elliott.pdf
 
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Mike Dean said:
Covid: Antibodies 'fall rapidly after infection'
"Immunity is waning quite rapidly, we're only three months after our first [round of tests] and we're already showing a 26% decline in antibodies," said Prof Helen Ward, one of the researchers.
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This wasn't a prospective study, it was three separate cohorts at three different points in time. So there wasn't a "decline" in antibodies per se.

Participation was relatively low, providing the possibility of participation/sampling biases.

Across all three rounds, 37.7% of those invited registered, and 29.9% provided a valid (IgG positive or negative) result (Supplementary appendix table S1). The response rate declined slightly over the three rounds.
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If you already know you have COVID, are you going to bother to do the test or fill in the questionnaire?

Also note:
The sensitivity of finger-prick blood (self-read) for IgG antibodies was 84.4% (70.5, 93.5) in RT-PCR confirmed cases in healthcare workers, and specificity 98.6% (97.1, 99.4) in pre-pandemic sera.
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I am also astounded by several the ignorant comments by the scientists on the Science Media Centre site who clearly haven't read the study. Several "experts" simply assumed that this was a prospective study and responded as if the antibody positivity was measured in the same participants more than once.
 
Mike Dean said:
Covid: Antibodies 'fall rapidly after infection'
"Immunity is waning quite rapidly, we're only three months after our first [round of tests] and we're already showing a 26% decline in antibodies
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What can be read into this - does it mean our immunity is likely to fade over time? Ie a potential vaccine effect would fade?
 
BurnA said:
What can be read into this - does it mean our immunity is likely to fade over time? Ie a potential vaccine effect would fade?
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No, we can not infer this at all, as the people in each cohort were not tested more than once. The difference in test results between the 3 cohorts could simply be due to participation biases.

Other studies have shown that despite a modest drop of IgG from the peak, IgG responses are durable. This is typical of most viral infections and vaccines.
 
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MIT developing ’heated face masks’ to kill off coronavirus

http://www.msn.com/en-gb/news/world...-kill-off-coronavirus/ar-BB1asiMS?ocid=ASUDHP

Engineers at the Massachusetts Institute of Technology (MIT) have submitted a patent for a prototype mask with a heated copper mesh, a news release from the university announced.

The researchers believe that the mesh in the masks will slow and inactivate any viral particles in the air.
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If they've got to the stage of patenting it, one would hope they have more evidence than just "believing" that it will work as specified, but these days, who knows? I suppose it could be speculative.
 
@Jonathan Edwards

"Broadly-targeted autoreactivity is common in severe SARS-CoV-2 Infection"
https://www.medrxiv.org/content/10.1101/2020.10.21.20216192v1.full.pdf+html

Our findings invite two interpretations. Either patients with undocumented and pre-existing autoimmunity comprise the majority of the critical illness within our Atlanta-based cohort, or more likely, the immunological environment of serious COVID-19 infection, including TLR7 activation by SARS-CoV2 ssRNA, is sufficient to drive de novo autoreactivity against a variety of self-antigens. The latter possibility has been documented in the setting of other serious infections10, and is now mechanistically supported through independent validation of autoimmune-prone EF response activation in serious disease6
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Snow Leopard said:
@Jonathan Edwards

"Broadly-targeted autoreactivity is common in severe SARS-CoV-2 Infection"
https://www.medrxiv.org/content/10.1101/2020.10.21.20216192v1.full.pdf+html
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Interesting but difficult to know how to interpret. A prospective study with follow up would be more meaningful.
San and co have been interested inertia-follicuar B cell activation for some time, as were we at UCL - looking at antibodies bearing the VH4-34 framework epitope recognised by the 9G4 reagent. Autoreactive antibodies during acute illness may not be that surprising but I do not know of comparable studies of other infections. It would also be interesting if asymptomatic pre-existing ANA or RF predicted serious sequelae from Covid.
 
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