Symptomatic, Asymptomatic, Presymptomatic: Who Can Spread The Coronavirus?- 6/9/2020
Evidence Supporting Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 While Presymptomatic or Asymptomatic
Abstract
Recent epidemiologic, virologic, and modeling reports support the possibility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission from persons who are presymptomatic (SARS-CoV-2 detected before symptom onset) or asymptomatic (SARS-CoV-2 detected but symptoms never develop). SARS-CoV-2 transmission in the absence of symptoms reinforces the value of measures that prevent the spread of SARS-CoV-2 by infected persons who may not exhibit illness despite being infectious. Critical knowledge gaps include the relative incidence of asymptomatic and symptomatic SARS-CoV-2 infection, the public health interventions that prevent asymptomatic transmission, and the question of whether asymptomatic SARS-CoV-2 infection confers protective immunity.
CDC to be published 7/26/20: https://wwwnc.cdc.gov/eid/article/26/7/20-1595_article
Asymptomatic Transmission, the Achilles’ Heel of Current Strategies to Control Covid-19
https://www.nejm.org/doi/full/10.1056/NEJMe2009758
SARS-CoV-2 viral load and the severity of COVID-19
University of Oxford Centre for Evidence Based Medicine
Does high COVID-19 viral load mean more risk of infection?
Surgical Masks Provide Source Control of Respiratory Viruses
https://www.jwatch.org/na51322/2020/04/13/surgical-masks-provide-source-control-respiratory-viruses
British Medical Journal- Viral load dynamics and disease severity in patients infected with SARS-CoV-2 in Zhejiang province, China, January-March 2020: retrospective cohort study
Good summary of where they find the virus in the body and for how long.
“Conclusion
The duration of SARS-CoV-2 is significantly longer in stool samples than in respiratory and serum samples, highlighting the need to strengthen the management of stool samples in the prevention and control of the epidemic, and the virus persists longer with higher load and peaks later in the respiratory tissue of patients with severe disease.”
NIH study:
A RAPID SYSTEMATIC REVIEW OF THE EFFICACY OF FACE MASKS AND RESPIRATORS AGAINST CORONAVIRUSES AND OTHER RESPIRATORY TRANSMISSIBLE VIRUSES FOR THE COMMUNITY, HEALTHCARE WORKERS AND SICK PATIENTS (Pre-pub online release, scheduled for publication 8/2020)
Conclusion
The study suggests that community mask use by well people could be beneficial, particularly for COVID-19, where transmission may be pre-symptomatic. The studies of masks as source control also suggest a benefit, and may be important during the COVID-19 pandemic in universal community face mask use as well as in health care settings. Trials in healthcare workers support the use of respirators continuously during a shift. This may prevent health worker infections and deaths from COVID-19, as aerosolisation in the hospital setting has been documented.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7191274/
Visualizing Speech-Generated Oral Fluid Droplets with Laser Light Scattering
https://www.nejm.org/doi/full/10.1056/NEJMc2007800
Wearing face masks in the community during the COVID-19 pandemic: altruism and solidarity (4/20)
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30918-1/fulltext
This is a well-researched article- but not research- but I thought the information about blood vessel disease was important to share.
Tackling airborne transmission of COVID-19 indoors. University of Surrey, UK
https://www.sciencedaily.com/releases/2020/05/200528115750.htm
Indoor transmission of SARS-CoV-2
This is also a pre-print article- not yet peer reviewed, discussing spread in various venues in China.
https://www.medrxiv.org/content/10.1101/2020.04.04.20053058v1
Background: By early April 2020, the COVID-19 pandemic had infected nearly one million people and had spread to nearly all countries worldwide. It is essential to understand where and how SARS-CoV-2 is transmitted. Methods: Case reports were extracted from the local Municipal Health Commissions of 320 prefectural cities (municipalities) in China, not including Hubei province, between 4 January and 11 February 2020. We identified all outbreaks involving three or more cases and reviewed the major characteristics of the enclosed spaces in which the outbreaks were reported and associated indoor environmental issues. Results: Three hundred and eighteen outbreaks with three or more cases were identified, involving 1245 confirmed cases in 120 prefectural cities. We divided the venues in which the outbreaks occurred into six categories: homes, transport, food, entertainment, shopping, and miscellaneous. Among the identified outbreaks, 53.8% involved three cases, 26.4% involved four cases, and only 1.6% involved ten or more cases. Home outbreaks were the dominant category (254 of 318 outbreaks; 79.9%), followed by transport (108; 34.0%; note that many outbreaks involved more than one venue category). Most home outbreaks involved three to five cases. We identified only a single outbreak in an outdoor environment, which involved two cases. Conclusions: All identified outbreaks of three or more cases occurred in an indoor environment, which confirms that sharing indoor space is a major SARS-CoV-2 infection risk.
Understanding the indoor pre-symptomatic transmission mechanism of COVID-19
(This is not yet peer reviewed- but says that most asymptomatic spread may be person to person rather than airborne.)
https://www.medrxiv.org/content/10.1101/2020.05.12.20099085v1
Kennett COVID Information 