Well, that escalated quickly. It’s official…the novel coronavirus SARS-CoV-2 is here. This article is to serve as an ongoing summary of pertinent literature with respect to the COVID-19 causing pandemic. As an Emergency Physician, I am sincerely impressed with the strides the scientific and medical community are taking to learn about this virus, how it works and how we can combat it. We are all in this together, and we will get through this together. So, stay tuned for updates as our knowledge and experiences grow…
How many cases are there?
Certainly, the true number of people infected with COVID-19 in unknown.
Johns Hopkins has a dynamic tracker that is monitoring the number of positive tests (click the scary looking picture to the right to see this), but certainly the true number of people who are currently infected are likely much, much higher.
Lack of available testing resources and asymptomatic carriers and those with mild disease with the instruction to self isolate no doubt leads to a significant number of unchecked cases.
But what if we tested more...
Certainly we would find more cases. So, is there literature that show benefit to knowing who would test positive, even if the person is asymptomatic?
In the town of Vò, near Venice, researchers tested and retested every person and answer just that.
Phase 1: In February, they tested the entire town (roughly 3,300 people) after Italy’s first confirmed death. They found 3% of the population was already infected and 50-75% of the COVID-19 causing carriers had no symptoms at all.
Phase 2: They isolated all of those infected, and repeated a second round of testing at 10 days. They found the infection rate dropped to 0.3% and identified another 6 individuals who were then quarantined.
Outcome: Early quarantine decreased the evolution towards serious illness as the rate of recovery was much quicker (8 days in 60% of patients). More importantly, they were able to completely stop the spread of illness there.
This method is in stark contrast to the “herd immunity” strategy used in the UK and Netherlands
Initial reports on a low mortality of only 2% sparked many nations such as the UK and Netherlands to adopt a “herd immunity” approach. That is, let people live their lives, get infected and just get this thing over-with. Like pulling off a band-aid. However, they quickly learned that the rate of spread and the propensity for a disproportionately higher risk of mortality in those over the age of 65 and those who are chronically ill, significantly overwhelmed the healthcare system. You can read a very sobering account of one UK physicians realization of this fact here.
In the case of Lombardy Italy, doctors were faced with the sobering task of rationing medical care. 1,335 people decompensated to the point of needing intensive care within a 3 week period, with a capacity of only 720 ICU beds. Further, they claim an 80-90% occupancy this time of year at baseline even without the threat of a global pandemic. Italy is seeing an exponential growth of ICU admissions and if this continues, this number is expected increase to over 14,000 patients by March 20th.
In the case of Wuhan China, only 25% of patients who died had access to ventilators.
To put this into perspective in the USA…
- MD’s per 1,000 people: Italy 4.0, USA 2.6
- Hospital beds per 1,000 people: Italy 3.2, USA 2.8
Are there enough ventilators in the US?
A report published February of 2020 from Johns Hopkins suggests the United States has 160,000 ventilators. 62,000 are full-featured mechanical ventilators (46% of which can be used on pediatric patients). The other 98,000 can provide limited basic ventilation during times of crisis. There are an additional 8,900 ventilators being held in the CDC national stockpile.
Further, according to the American Hospital Association, there are a total of 924,107 hospital beds in the United States.
In a report from the Institute for Disease Modeling, COVID-19 is only slightly less severe than the 1918 Spanish flu, and nearly as transmissible (photo right).
According to a 2005 Health and Human Services action plan, the United States would need mechanical ventilators for 740,000 patients in the event of a pandemic like the 1918 Spanish flu.
So, do we have enough ventilators?
…ehhhh, probably not…
Source: Institute for Disease Modeling report, highlights the clinical severity for 2019-nCoV relative to various years of pandemic and seasonal influenza.
How fast is this thing spreading?
Each person infected with COVID-19 will, on average, infect about 2.5 other people. We call this value the R0 (pronounced R naught). Each of those people will infect another 2.5 each and so on with about 5 days in between each infection. So in just one month, we would expect 2.5^6, or 244 cases. This doesn’t sound like a lot, does it? Consider this…it will take just 28 doublings to infect 256 million people in the US. At a doubling time of every 5 days, that could occur in just 4 months if we did nothing to slow the spread.
This exponential growth is why locations like Seattle and Italy are describing seeing 1 or 2 critical cases, then a sudden explosion of illness “like a bomb going off.”
According to models from the CDC, if we did nothing to slow this progression, we could expect between 160-214 million people infected in the United States with as many as 200,000 to 1.7 million deaths.
Flattening the Curve...
The R0 of a virus isn’t fate, we can control this number with proper hygiene and social distancing such as canceling mass gatherings, working from home, and even shutting schools and universities.
In one model, as of 03/01/2020, it is likely that there were already thousands of individuals in the US infected with SARS-CoV-2.
The concerning aspect of the spread of SARS-CoV-2 is that everyone is getting most sick at the same time, overwhelming the healthcare system. With social distancing, the area under the curve remains unchaanged, but we can distribute the illness over a longer duration of time and give our healthcare system a fighting chance.
So does it work...
Heck yeah, man! This is data from the Spanish flu of 1918. St. Louis practiced social distancing. Philadelphia did not…
Source: NY Times
Countries like Hong Kong and Singapore have been able to stop the exponential spread of the virus by implementing early and strong social distancing practices. They implemented early school closures, eliminated mass gatherings, initiated aggressive decontamination of public buses and municipalities and conducted widespread testing.
Isolate those infected
Isolation separates sick people with a contagious disease from people who are not sick.
According to the WHO mission to china report, SARC-CoV2 isolates are found in the upper respiratory tract in pretty much all patients from 1-2 days before symptom onset to 7-12 days after. In 30% of patients, viral RNA is found in the stool form 5 days after symptom onset and up to 5 weeks. However, literature out of Singapore shows prolonged viral shedding from nasopharyngeal aspirates for at least 24 days after symptom onset. Prolonged viral shedding has also been seen in children with similar duration as adults (24 days in respiratory samples and 1 month in stool samples).
As we previously discussed, asymptomatic people can certainly be carriers. Further, the viral load of asymptomatic patients appears to be similar to symptomatic patients, which highlights their transmission potential. Investigators report that the viral load of asymptomatic patients is similar to symptomatic patients, indicating a transmission potential of asymptomatic or pre-symptomatic patients.Further, with documented incubation periods ranging from 0 to 24 days, there appears to be clear benefit in testing asymptomatic patients before being released from isolation.
The significance of viral shedding has not yet been clarified and the persistence of viral RNA in body fluids does not necessarily mean the person is infectious. Isolation of the virus in cultures are needed to show infectivity.
However, this data highlights the importance of prolonged viral shedding from the GI tract, especially if removal of isolation is determined by negative oral swabs. For patients who are discharged after an improved clinical course, strict personal hygiene precautions must be discussed with this in mind.
Comparison of hospital/isolation discharge criteria (Updated March 18)
Quarantine
Quarantine separates and restricts the movement of people who were exposed to a contagious disease to see if they become sick.
People who may have been exposed to an infection are asked to remain at home, or in another place, isolated from other people. Quarantines can target just individuals who have traveled to affected countries, or could end up involving large groups of people (say, if a school’s entire student body may have been exposed to the infection). In the case of Italy, it meant the entire country.
You can certainly see the benefits of quarantine based on the data we have already reviewed. But what the need to quarantine cannot be maintained. For instance: At this time, if healthcare workers become exposed to a patient with COVID-19 and did not have the appropriate PPE, the recommendation is for self quarantine. Well, as an Emergency Physician, I can tell you that the number of opportunities to be exposed to an individual and caught off guard without the appropriate PPE is a very real possibility. Especially given the extremely large potential to be an asymptomatic carrier.
To think that every time a healthcare worker I exposed, that they would be able to quarantine for 14 days is completely not sustainable. We would quickly run out of health care workers. In the absence of quarantine; hospitals would serve as a disease amplifier of the communities most sick and vulnerable. This is why it is important to protect the healthcare workers to maintain a healthy hospital workforce.
Italy is currently letting this year’s 10,000 medicine graduates to start work 9 month ahead of schedule and waive the mandatory exams they normally sit before qualifying to deal with the shortage of healthcare providers in the country.
“There’s a point where we stop trying to quarantine anyone and we just say, OK, we’re going to have more deaths from the fire department not being able to fight fire than from everyone getting the disease.”
Isn't it just a really bad flu?
That is going to be a hard no…
There has now been enough published literature to give us some consistent insight. While it certainly seems to really hit those above the age of 65, unless you are under the age of 9, your risk of death is increased significantly compared to the seasonal flu.
Patients less than 19 years of age have a 14-25 times higher risk of death from COVID-19 than they do from the flu. Anyone over the age of 80 who gets the disease appears to have a nearly 15% chance of dying from it.
Some Important Trends
- Some are seeing a pattern of clinical deterioration during the second week of illness (Huang).
- Highest rate of hospital admission seems to be around days 8-9 (Huang).
- ARDS develops in up to 29% of hospitalized patients (Huang).
- Secondary infection develops in 10% (Chen).
- Up to 32% of those hospitalized required ICU admission (Wang).
- 11% needed high flow oxygen
- 42% needed NIPPV
- 47% needed mechanical ventilation
- 10% of all admitted patients will need mechanical ventilation (Wang).
- In hospital mortality currently as high as 15% (Wang).
- Among those discharged alive, the median hospital stay is 10 days (Wang).
Nosocomial Spread
One study, published in JAMA looked at the persistence of the SARS-CoV-2 virus in hospital rooms of three patients infected with SARS-CoV-2 and from the personal protective equipment (PPE) worn by the physicians as they left their room.
Methods: 3 patients at the dedicated SARS-CoV-2 outbreak center in Singapore in airborne infection isolation rooms (12 air exchanges per hour) with anterooms and bathrooms had surface environmental samples taken at 26 sites. Personal protective equipment (PPE) samples from study physicians exiting the patient rooms also were collected. Sterile premoistened swabs were used. Samples were collected on 5 days over a 2-week period. One patient’s room was sampled before routine cleaning and 2 patients’ rooms after routine cleaning. Twice-daily cleaning of high-touch areas was done using 5000 ppm of sodium dichloroisocyanurate. The floor was cleaned daily using 1000 ppm of sodium dichloroisocyanurate.
Results: Patient A’s room was sampled on days 4 and 10 of illness while the patient was still symptomatic, after routine cleaning. All samples were negative. Patient B was symptomatic on day 8 and asymptomatic on day 11 of illness; samples taken on these 2 days after routine cleaning were negative. Patient C, whose samples were collected before routine cleaning, had positive results, with 13 (87%) of 15 room sites (including air outlet fans) and 3 (60%) of 5 toilet sites (toilet bowl, sink, and door handle) returning positive results. Anteroom and corridor samples were negative. Patient C had upper respiratory tract involvement with no pneumonia and had 2 positive stool samples for SARS-CoV-2 on RT-PCR despite not having diarrhea. Only 1 PPE swab, from the surface of a shoe front, was positive. All other PPE swabs were negative. All air samples were negative.
Discussion: This highlights both the importance and the efficacy of simply cleaning the room. It also makes me wonder why booties are not part of the recommended PPE. It is important to note, that the rooms in this study were all airborne isolation rooms with 12 air exchanges per hour. Further literature will need to look at similar parameters for patients not in airborne isolation with regard to provider PPE.
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