Epidemiology and Contagion

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EPIDEMIOLOGY AND CONTAGION

 

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VIRAL TRANSMISSION

 

Handout on Handwashing from Johns Hopkins
This may be useful for posting regarding proper disinfection procedures.
Handwashing advice from Johns Hopkins.pdf

 

Dr. Muckherjee on Covid-19 Infection from the NYT
Noted physician author Dr. Siddhartha Mukherjee notes that size of Covid-19 inoculum may be important in outcome for an individual patient: the practical implication for a provider is minimizing closeness and duration of contact.
https://www.newyorker.com/magazine/2020/04/06/how-does-the-coronavirus-behave-inside-a-patient

 

Research on the Efficacy of Different Mask Materials
Your patients may be asking about home-made cloth masks. This is the widely quoted study that suggests that two layers of tea towel are almost as good as a surgical mask.
https://www.researchgate.net/profile/Katy-Anne_Thompson2/publication/258525804_Testing_the_Efficacy_of_Homemade_Masks_Would_They_Protect_in_an_Influenza_Pandemic/links/53fefd8f0cf21edafd154e85/Testing-the-Efficacy-of-Homemade-Masks-Would-They-Protect-in-an-Influenza-Pandemic.pdf

 

This page explains why particles smaller than 0.3 microns may be easier to filter (coronavirus being about 0.125 microns in size).
https://smartairfilters.com/en/blog/what-is-pm0-3-why-important/
A number of centers have published research on the most effective fabric types, and find that densely-woven fabric or non-woven interfacing material are best
https://www.nytimes.com/article/coronavirus-homemade-mask-material-DIY-face-mask-ppe.html

Coronavirus Seasonality
A recent study emphasizes the seasonal nature of typical coronaviruses.
https://academic.oup.com/jid/article/doi/10.1093/infdis/jiaa161/5815743Unfortunately, the most recent research review from the National Academies Press suggests that Covid-19 will not display the same pattern.
http://nap.edu/2

 

Recent Research Suggests Surgical Masks Inadequate in Clinical Contexts
Recent research raises concerns about the adequacy of protection by surgical masks, implying C-L practitioners should wear N95 gear where virus exposure is possible. Dr Fears et al show that the aerosol efficiency (plaque forming units in aerosol vs solution) of Covid-19 appears to exceed that of SARS or MERS, and also show that aerosol infectivity shows little decay over 16 hours.
https://www.medrxiv.org/content/10.1101/2020.04.13.20063784v1.full.pdf

Dr Chia et al show that airborne particles in the 1 to 4 micron range contain a significant fraction of airborne Covid-19 virus in patient rooms, with maximal levels in the first week of illness. Note that standard surgical masks are not designed to provide efficient protection from particles in this size range.
https://www.medrxiv.org/content/10.1101/2020.03.29.20046557v2.full.pdf

Dr Liu et al find low airborne virus RNA in ventilated negative-pressure patient rooms but find occasional high concentrations in unventilated patient toilet areas, crowded public hospital areas, and areas where staff removed protective gear.
https://www.nature.com/articles/s41586-020-2271-3_reference.pdf

These results are consistent with a randomized clinical trial conducted in winter 2009-10 in Beijing with healthcare workers in emergency or respiratory ward settings, excluding workers with facial hair. Upper respiratory infection rates were 7% with continuous use of N95 respirators and 17% with surgical masks.
https://www.atsjournals.org/doi/full/10.1164/rccm.201207-1164OC?url_ver=Z39.88-2003

The CDC advises against facial hair in the sealing zones of respirators, a warning likely of greater relevance to psychiatrists than to members of any other medical specialty

 

 

Summary Accounts of Research on Covid-19 Transmissibility
Erin S. Bromage, PhD, an animal infectious disease researcher at the Department of Biology, University of Massachusetts Dartmouth, has provided clear summaries of the literature on Covid-19 mechanism of spread, patterns of spread, and survival on surfaces (first three links). Jonathan Kay is a journalist and an editor at Quillette, a nonprofit online magazine, and his analysis of superspreader events is the fourth link (see his other blog posts too). Both authors reference the key Chinese study on transmissibility (fifth link).
https://www.erinbromage.com/post/the-risks-know-them-avoid-them
https://www.erinbromage.com/post/where-we-are-now
https://www.erinbromage.com/post/how-do-we-kill-sars-cov2-on-surfaces
https://quillette.com/2020/04/23/covid-19-superspreader-events-in-28-countries-critical-patterns-and-lessons/
https://www.nature.com/articles/s41591-020-0869-5

Early Treatment with Corticosteroids Improves Disease Course
Dr. Raef Fadel, DO, and coworkers at the Henry Ford Hospital describe improved mortality and other disease outcomes with prompt corticosteroid treatment in moderate to severe Covid-19 infection in this quasi-experimental study with 213 subjects.
https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa601/5840526

NEJM Video about Donning and Doffing PPE
Another well-produced video from the NEJM.
https://www.nejm.org/doi/full/10.1056/NEJMvcm2014809

New Review of Covid-19 Psychopharmacology in Psychosomatics
ACLP members Drs. Anna Kim and Carrie Ernst and others provide an analysis of psychopharmacology in the Covid-19 patient.
https://www.sciencedirect.com/science/article/pii/S0033318220301444

Aerosol Mechanisms of InfectivityAnother Worrisome Study of Aerosol Mechanisms of Infectivity
Drs. Stadnytskyi et al. estimate the half-life of airborne droplets generated by speech in stagnant air to be 8 to 14 minutes (incidentally, they believe the “th” sound particularly effective for generating such particles).
https://www.pnas.org/content/early/2020/05/12/2006874117

 

 

Meta-Analysis of Corona Virus Contagion and Physical Distancing, Mask Use
Chu et al. perform a meta-analysis of 172 studies with SARS, MERS, or Covid-19 contagion, surmising a risk decrease of 82% with one-meter distance (and a two-fold decrease with each additional meter), of 96% with N95 or similar respirators, and of 77% with ordinary face masks. The results strongly argue for use of N95 masks only for all healthcare workers in risk situations.
https://www.thelancet.com/action/showPdf?pii=S0140-6736%2820%2931142-9

Social Disparities in the Impact of Covid-19
Racial, ethnic, and socioeconomic disparities are becoming dramatically obvious in the current pandemic (first link). For example, in New Haven, CT, the rate of Covid-19 infection in the poorest neighborhood area was at one point almost 50 times that in the wealthiest area. A disproportionate impact on black Americans was evident in the 1918 pandemic as well (second link).
https://jamanetwork.com/journals/jama/fullarticle/2764789
https://doi.org/10.7326/M20-2223

Mask UseWidespread Mask Use Likely Highly Effective in Reducing Pandemic Spread
Richard O. J. H. Stutt et al. present mathematical modelling that even fabric masks could radically decrease Covid-19 spread but only if worn by a high fraction of the population for a high fraction of the time.
https://doi.org/10.1098/rspa.2020.0376

 


EPIDEMIOLOGY

Book: Psychiatry of Pandemics: A Mental Health Response to Infection Outbreak, by Damir Huremović, MD, MPP, FACLP
Dr. Huremović is likely the only ACLP member to have edited a book on the psychiatry of infectious epidemics. This link may open a pdf of the book if activated within your institutional network.
https://link.springer.com/book/10.1007/978-3-030-15346-5

Epidemiological incidence tracking
The Financial Times provides this continuously updated resource. Plotting data as a function of days since threshold of case incidence per country appears to have been the idea of their analyst, John Burn-Murdoch, whose Twitter blog is still excellent (https://twitter.com/jburnmurdoch). The first graph is from March 23, 2020, when this webpage began. At that time the US, Italy, and Spain seemed to have similar numbers of cases. Little did we expect that the US would come to represent the largest national number of cases, with a further acceleration after June 20. Brazil and India have emerged as centers with exponential growth. Europe appears to have moderated the spread of the virus, with an ominous recent trend towards increasing slope, while Russia is reporting a slower rate of case accumulation.
https://www.ft.com/coronavirus-latest

Epidemiological incidence tracking

Epidemiological incidence tracking

In the following graph, the incidences of new cases per million population are shown. The US and Brazil have now exceeded the incidence per capita seen in the European Union region overall.

Epidemiological incidence tracking

Compared to the European countries, Spain and Belgium exceeded the early US peak of incidence per capita, but the US incidence per capita has now risen above these levels. We note the ominous evidence of rising incidence in some countries of Europe.

Epidemiological incidence tracking

New deaths per million are now rising in the US with a predictable lag.

Epidemiological incidence tracking

In a cumulative plot of deaths per million, the US appears poised to catch up with its European counterparts. If the US achieves the death rate in Belgium (861/million), this would represent total deaths of >284,000.

Epidemiological incidence tracking

Comparative Risk by US County
This site estimates risk on a real-time basis by rolling 7-day average of new cases per 100,000.
https://globalepidemics.org/key-metrics-for-covid-suppression

Comparative Risk by US County

Epidemiological geographical tracking
This is from the Johns Hopkins Center for Systems Science and Engineering (CSSE), whose website also provides detailed analysis of the Covid-19 crisis.
https://www.arcgis.com/apps/opsdashboard/index.html#/bda7594740fd40299423467b48e9ecf6

 

Epidemiological geographical tracking

 

Modeling the Effect of Social Distancing
Dr Sheryl Chang and colleagues model the effect of interventions for slowing pandemic spread in Australia. Social distancing with 90% compliance (yellow solid line) or 80% compliance (orange solid line) are effective but 70% compliance is ineffective (blue solid line), while delaying 3 days reduces effectiveness (dashed lines). Ending social distancing results in rapid resumption of spread.
https://arxiv.org/pdf/2003.10218v2.pdf

This figure from the NYT emphasizes that social distancing works, but also that most of the US is not successfully applying this strategy.

ny-v-us-cases-for-newslettter-articleLarge

Low Prevalence of Covid-19 Infection in Iceland Population
Random nasopharyngeal swab testing discloses only 0.8% prevalence of Covid-19 in Iceland, eliminating the hypothesis that a significant fraction of the population had asymptomatic infection. This discouraging finding suggests the pandemic has far to go before population immunity occurs and epidemic spread stops. Interestingly, more men were infected than women, 0.9% vs 0.6%, for which we still have no explanation.
https://www.nejm.org/doi/10.1056/NEJMoa2006100 

CIDRAP Report Predicts 18 to 24 Months Duration for Covid-19 Crisis
A report by Dr Michael Osterholm, PhD, MPH, and colleagues from the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota predicts that Covid-19 will require 18 to 24 months to reach >70% infection rates and subside, and they offer three alternative scenarios of repeated waves of infection, a large wave of infection next fall/winter followed by smaller waves, or continuing variable infection.
https://www.cidrap.umn.edu/sites/default/files/public/downloads/cidrap-covid19-viewpoint-part1_0.pdf

Grim Effects of Delay in Social Distancing and Other Control Measures
Drs. Sen Pei, Sasikiran Kandula, and Jeffrey Shaman model Covid-19 spread prior to May 3 and estimate that starting control measures one week earlier would have avoided 62% of cases and 55% of deaths in the US. Shown are inter-county commuting data and social distancing impact on effective reproductive number, Re.
https://www.medrxiv.org/content/10.1101/2020.05.15.20103655v1.full.pdf

Delay in Social Distancing and Other Control Measures