C19 Notes
General Category => C19 Notes Database => Topic started by: stog on June 05, 2020, 09:13:38 AM
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a Quick summary of covid literature so far by two HIV clinical fellows at Boston hospitals have recorded a biweekly deep dive into the most compelling COVID-19 data. this is snapshot as at may 18 2020 this is page 3 so there is more -- move left at bottom of page
https://www.medscape.com/viewarticle/930588#vp_3 (https://www.medscape.com/viewarticle/930588#vp_3)
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Here are some key points from our first three presentations that are still valid.Viral Shedding: Key Points
- Nasopharyngeal viral load peaks around 1 day prior to symptom onset, correlating to peak time of infectiousness.
- Saliva may become an important sampling site for diagnosis.
- SARS-CoV-2 is a descending infection; in later disease, viral loads are higher in the lower respiratory tract (especially in severe/critical illness).
- In mild cases, live virus is isolated up to day 8 after symptom onset.
- There can be prolonged shedding of viral RNA lasting many weeks, particularly after critical illness. Correlation with infectiousness is unknown.
- Studies differ on whether severity of illness correlates with viral load.
- In some cases, viral RNA has also been identified in the stool, blood, conjunctiva, urine, cerebrospinal fluid, and pleural fluid.
SARS-CoV-2 Seroprevalence- Studies with (near) universal screening of various populations are increasingly available, finding a wide range of asymptomatic people with positive RT-PCR tests.
- Pregnant women in NYC: (https://doi.org/10.1056/NEJMc2009316) 13.5% (87% of total infections)
- Homeless shelter in Boston (https://doi.org/10.1101/2020.04.12.20059618): 36% (great majority of infections)
- Town in Italy: (https://doi.org/10.1101/2020.04.17.20053157) < 1% (41% of total infections)
- Iceland (https://doi.org/10.1056/NEJMoa2006100): < 1% (43% of total infections)
- Diamond Princess cruise ship (https://doi.org/10.15585/mmwr.mm6912e3): 9% (46% of total infections)
- Varying rates relate to local stage of epidemic, population and sampling, and mitigation strategies in place.
- Some asymptomatic people are likely to be presymptomatic given the variable and sometimes lengthy incubation period.
Viral Entry: Key Points- ACE2 is an important receptor for viral cellular entry.
- TMPRSS2 primes the S protein and allows for efficient cellular entry.
- An interaction between SARS-CoV-2 and CD147 may facilitate invasion.
- Many unresolved questions remain regarding the exact role of CD147 in viral entry. Does it directly interact with the S protein or is the interaction mediated by CypA and the N protein, as was found for SARS-CoV?
What Else Have We Learned?Key observations from our first three updates that are still relevant:- Peak infectiousness is probably 1 day prior to symptom onset.
- In the absence of therapy/vaccine, intermittent social distancing is likely to be needed for years to avoid overwhelming critical care capacity.
- Emerging pathologic correlates of clinical presentations:
- Multiple mechanisms of cardiac injury
- Virus can cause systemic infection
- Viral endotheliitis and possible complement activation as cause of micro/macro thromboses
- Obesity (https://emedicine.medscape.com/article/123702-overview) is a risk factor for severity of disease.
- Hypercoagulability is a key feature of the disease.
- Age-based sheltering is unlikely to be effective without social distancing.
- Epidemic control is feasible with contact tracing if minimal delay is achieved.
- Asymptomatic/presymptomatic transmission is substantial.
- The incubation period is highly variable (median, 5 days).
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here is the table key findings in mode of transport, and the clinical course
all taken from the summary link in main post