We have done a fair bit of evaluation on COVID-19 in general, but not all of it has made its way to this references page. If you spot any especially relevant gaps or information that is contradictory to any of these links, please let us know, as things are moving quickly and we haven’t had time to credibility check all links.
COVID-19 Disease Progression (and feasibility implications)
Analysis performed up to 2020-03-20
- Incubation (time from infection to symptoms):
- 0-24 day
- 4-5 days average
- 5.1 days median (alt source: 3 day)
- 97.5% of cases within 11.5 days
- 99% of cases within 14 days
- Non-silent pneumonia development (time from infection to pneumonia criteria threshold)
- 7.2 – 19 days
- 10-11 days average
- 2.75% of cases before 6-7 days
- 97.5% of cases with pneumonia, within 16 days
- For some studies it is not currently clear what detection method / threshold criteria studies have used
- https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf (Clinical presentation of initial stage of pneumonia, PRE-ARDS so shortness of breath/ rapid breathing)
- Example general timeline
- Day 1: fever. Lesser chance of fatigue, muscle pain, dry cough. Rare diarrhea or nausea 1-2 days before fever
- Day 5: difficulty breathing (typically pneumonia related)
- Day 7: average admission into hospital
- Day 8: sever cases develop Acute Respiratory Distress Syndrome (ARDS)
- Day 10: some sever cases progress to critical, this is when admitted to ICU
- Day 17: average time people are released from hospital
- Frequency of symptoms (note the questionnaire portion of data samples, track several other symptoms, supplemented by our sensor data):
- Pneumonia: [TBD]
- Silent pneumonia: unknown
- Asymptomatic patients can have silent pneumonia/ground glass opacities
- There is a period of time before pneumonia is present, suggesting a multi-day progression of initially silent pneumonia that may be detectable.
- Fever will often, but not always, appear before pneumonia; however fever has a broader range of potential causes. We nonetheless should track fever symptoms at the same time.
COVID-19 Pandemic Progression (and feasibility implications)
Analysis performed up to 2020-03-20
- World Health Organization says some nations aren’t running enough coronavirus tests: ‘Test every suspected case.’ “But we have not seen an urgent enough escalation in testing, isolation and contact tracing, which is the backbone of the response,” Director-General said.
- UK Prime Minister Boris Johnson has said a big increase in testing is the way to “unlock the puzzle” of the UK coronavirus outbreak.
- “What we really need to focus on is finding those who are sick, those who have the virus, and isolate them, find their contacts and isolate them,” Mike Ryan said in an interview on the BBC’s Andrew Marr Show.
Testing is important and, with a shortage of testing capacity, targeting testing to those with higher probability is key. But, at later stages of the pandemic, community spread limits the effectiveness of targeting by case-tracking.
- Layman primer: [TBD]
- Sound of lungs typical of COVID-19 infections:
- Frequency of pneumonia “crackles”: 60 – 2,000 Hz, with emphasis on 60-1,200 Hz
- Percussion sound reference: https://www.rnceus.com/resp/respperc.html
Long-Term Lung Damage in Recovered Patients
- May cause pulmonary fibrosis in 25% of people, causing loss of 20-30% of lung function
- Liver damage (unclear what is the cause, maybe the virus binding to Ace2 or from treatment drugs). In general damage occurs in between 14.8-53% of people with COVID-19. The proportion of people with severe cases had higher instances then mild. In critical patients who die, liver damage is between 58.06-78%
- Preliminary reports that even asymptomatic patients are experiencing lung damage; this suggests that detection before symptoms would be possible, as lung damage would change acoustics:
Individuals submitting baselines using Caredemic may help screen those people with potential long-term changes to their lung function, even due to silent pneumonia.
Phone-Based Oximetry (Measuring Blood Oxygen Using Mobile Phone Cameras)
- Smart phone camera with LED can work close to as good as a commercial pulse oximeter.
- Without hypoxia (pneumonia) smartphone camera based app (app unknown) can accurately measure in children.
- Smart phones can measure oxygen saturation levels by using movement sensors to detect gate. Uses movesense software.
- Fitbit has the capacity to check 02 levels currently. Apple watch has hardware capacity but it has not yet been activated/enabled by Apple.
- Design of a low cost pulse oximeter for smartphone integration.
- Contradictory point: This study found that the iphone apps were NOT accurate.
We should explore this further to decide whether or not it should be included in collection.
COVID-19 Impact On Voice
- Direct anecdote from a respected Mexican doctor: she indicates she can frequently hear a sign of probable COVID-19 in a patient’s voice during regular speech.
- Carnegie Mellon University has made progress on an app that detects COVID-19 by coughing and talking. Our platform would go several steps further but incorporate their progress.
We can track anonymous usage of vocal cords. Full speech is probably unnecessary; instead we will explore more minimal approaches such as vowel sounds.
Misc Parking Lot of Items The Caredemic Team Is Looking Into
How many days before pneumonia is present in serious cases of COVID-19 (starts 5 days after initial symptoms, which emerge 2.2 -14 days after infection).
- Minimum 6-7 days (2.75% chance), Average 10-11 days, 97.5% within 16 days.
- Incubation https://annals.org/aim/fullarticle/2762808/incubation-period-coronavirus-disease-2019-covid-19-from-publicly-reported
- Clinical presentation of initial stage of pneumonia, PRE-ARDS so shortness of breath/ rapid breathing https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf
- When can you detect it with CT.
- On admission (median 8 days after contracting COVID-19) CT showed abnormalities, 98% of which were bilateral.
- ICU PATIENTS Typical findings were bilateral multiple lobular and subsegmental areas of consolidation.
- NON-ICU Typical findings were bilateral ground-glass opacity and subsegmental areas of consolidation; later CT shows consolidation had resolved but ground-glass remained.
- CT Scan shows progressive worsening up to 10 days after symptoms present, followed by improvement.
Timelines of when each symptom and phase emerges (e.g., asymptomatic lung damage).
(Timeline of normal disease progression from first onset of symptoms, which occurs on average 5 days after infection.) https://jamanetwork.com/journals/jama/fullarticle/2761044 )
- Timeline before person can infect, or the degree of infectiousness based on timelines.
- Most infectious 1-5 days after symptoms present. Least contagious beyond 10 days after first symptoms, probably due to immune response.
- Disease appears most infectious once symptoms emerge, but asymptomatic transmission may also occur.
- Is infectious before 1 week after exposure; 12.6% of cases caused by people who have no symptoms yet (asymptomatic). Serial interval of 3.96 days.
- Non-clinical or undocumented cases cause 79% of spread.
- What are all of the typical symptoms, and how early can each symptom be detected?
- (timeline to occurrence),
- (current detection method)
- (How can phone be used to detect)
- What can phone sensors accomplish related to physiology?
- Dyspnoea (shortness of breath)
- Median 8 days (IQR 5.0-13.0) Detection method is symptom.
- Median 9 days (IQR 8.0-14.0)
- Mechanical ventilation
- Median 10.5 days (7.0-14.0)
Symptoms in clinically presenting symptomatic cases
- MILD – 81% little or no nonsilent-pneumonia.
- SEVERE – 14% dyspnea, hypoxia, or >50% lung involvement within 24 to 48 hours.
- CRITICAL – 5% respiratory failure, Cytokine storm (shock), multi-organ dysfunction.
Differences between Type L (70% of strains in Wuhan) and Type S (Primary strain outside of China)
Importance of testing to curbing spread:
- “[We] cannot stop this pandemic if we don’t know who is infected. We have a simple message for all countries: test, test, test.” – Tedros Adhanom, Director General of the World Health Organization.
- “Testing is very important in terms of identifying cases so epidemiologists can then contact people exposed to individuals who are known to be positive and make recommendations about home isolation and further follow-up,” says Karen Carroll, professor of pathology and director of the Division of Medical Microbiology at Johns Hopkins.” https://www.hopkinsmedicine.org/coronavirus/screening-test.html
- “When a communicable disease outbreak begins, the ideal response is for public health officials to begin testing for it early. That leads to quick identification of cases, quick treatment for those people and immediate isolation to prevent spread.” – Dr. Eduardo Sanchez, American Heart Association Chief Medical Officer for Prevention
People not taking the symptoms seriously enough:
- “There is still considerable uncertainty around the fatality rates of COVID-19 and it likely varies depending on the quality of local healthcare. That said, it is around two percent on average, which is about 20 times higher than for the seasonal flu lineages currently in circulation.” – Francois Balloux, Professor of Computational Systems Biology at University College London.
- “[With the seasonal flu], when there are enough people in the community who are immune, it protects people who are not immune… That is the case with flu, but not with COVID-19.” – Luis Ostrosky, a member of the Infectious Diseases Society of America
- [A] few anti-viral drugs have been developed that blunt the impact of some influenza strains, but no such tool exists for the coronavirus.” – Matt Koci professor of immunology, virology, and host-pathogen interactions at North Carolina State University (edited)
- “The study concluded that 86 per cent of cases were ‘undocumented’ – that is, asymptomatic or had only very mild symptoms.” – Research published last week by Jeffrey Shaman of Columbia University in New York. https://www.newscientist.com/article/2238473-you-could-be-spreading-the-coronavirus-without-realising-youve-got-it/
- “10 per cent of new infections are being spread by either healthy-looking, asymptomatic people or people who have yet to develop the disease’s flu-like symptom. As much as 25 per cent of all U.S. cases [have] remained asymptomatic.” – Robert R. Redfield, Director of the CDC, as quoted in an interview with NPR
- “A joint Japanese-U.S.-U.K. study looked at data from the passengers on the Diamond Princess cruise ship who were quarantined for two weeks in Japan after the ship had an outbreak in February. The researchers determined that nearly 18 percent of those who were infected never showed symptoms.”
Shortage of testing
- “We do not have a capacity, and we will not have the capacity in the short or medium term to test every [person] who has a cough or a runny nose.” – Dr. Deena Hinshaw, chief medical officer of health for the province of Alberta, Canada.
- “Testing is essential for identifying people who have been infected and for understanding the true scope of the outbreak. But…academic, clinical, and other laboratories have struggled to get or make new tests and diagnose patients.”