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  • By now, you've probably heard of COVID-19,

  • or coronavirus disease discovered in 2019,

  • which is responsible for a global pandemic.

  • COVID-19 is caused by SARS-CoV-2,

  • or Severely Acute Respiratory Syndrome Coronavirus 2,

  • because it's genetically similar to the SARS Coronavirus,

  • which was responsible for the SARS outbreak in 2002 (2003).

  • Now, coronaviruses that circulate among humans are typically benign,

  • and they cause about 1/4 of all common cold illnesses.

  • In COVID-19, what happened is that there was a coronavirus circulating among bats,

  • which are a natural animal reservoir,

  • and it mutated just enough to start infecting an intermediate host

  • the Pangolin, an animal that looks like a cross between an anteater and an armadillo,

  • In late 2019, the corona virus mutated again and started causing disease in humans.

  • The outbreak began in China but has since spread around the world.

  • As of March 9th, 2020, or roughly 3 months into the outbreak

  • there have been 109,578 confirmed cases of COVID-19

  • and 3,809 deaths, resulting in a fatality rate of 3.5%,

  • but that represents an average across different countries and timeframes.

  • Based on a large study in China, digging deeper reveals that the fatality rate in China was actually

  • 16% for cases between January 1st and January 10th,

  • but then, it fell steadily over time until it was only 0.8% for patients with symptom onset after February 1st.

  • There are two main reasons for this:

  • first, the hospitals and clinics were initially overwhelmed and couldn't manage the disease,

  • so both patients and healthcare providers were getting severely ill and dying,

  • but within a few weeks with better equipment, testing, and processes in place,

  • the healthcare system responded and brought down the fatality rate dramatically.

  • Now as a point of comparison, the flu typically causes a fatality rate of 0.1%,

  • so even based on this data, COVID-19 is still 8 to 35 times more deadly than the flu.

  • It's also worth pointing out that for COVID-19, the mortality rates differ by group,

  • so for example, if you split things out by age,

  • you can see from this table that fatality rate is relatively low if you're below 60,

  • with no deaths seen in children at 9 and younger,

  • but then it starts to really climb up for the elderly,

  • so they're really the ones at highest risk.

  • Similarly, the fatality rate is higher for folks with hypertension, diabetes,

  • cardiovascular disease, chronic respiratory disease, and cancer,

  • relative to folks without any of these conditions.

  • and of course, a lot of the elderly typically have one or more of these conditions,

  • so it's not surprising that they go hand in hand.

  • Now, although the COVID-19 pandemic is still ongoing,

  • the good news is that in China and also in South Korea,

  • the number of new cases per day has dropped off

  • largely due to the aggressive public health measures like quarantining,

  • aggressive testing, and ensuring hospitals have the right equipment and staffing.

  • Based on the current data, over 80% of the patients with COVID-19 have a mild infection

  • and some people don't develop any symptoms at all.

  • For others, they can develop symptoms that can range from pretty mild

  • like fever, cough, and shortness of breath, all the way to serious problems like pneumonia.

  • Severe lung damage can cause Acute Respiratory Distress Syndrome or ARDS,

  • which occurs when the lung inflammation is so severe that fluid builds up around and within the lungs

  • the severe infection can cause septic shock

  • which happens when the blood pressure falls dramatically and the body's organs are starved for oxygen.

  • ARDS and shock are the main causes of death for people with the infection

  • and again this is most likely to occur in those over the age of 60,

  • smokers and people with other medical conditions like heart disease.

  • In addition to causing disease, coronaviruses can spread quickly,

  • usually the virus spreads when people cough or sneeze,

  • and tiny droplets containing the virus are released.

  • These droplets can land on another person's mouth, nose, or eyes,

  • and that allows the virus to enter a new person.

  • When a person with COVID-19 travels to a non-affected area, this is called an imported case.

  • If they start spreading the disease to household contacts and those around them,

  • it's called local transmission,

  • since it's usually isolated to a small area and can be easily traced back to the original person.

  • However, when people begin to contract the disease without a clear source,

  • it's called community transmission.

  • To prevent or contain community transmission, some schools and businesses have shut down;

  • and some conferences, sporting events, and other large gatherings have been postponed or cancelled.

  • Once a person is infected, symptoms develop about five days later,

  • this is called the incubation period.

  • Now there's debate about how much asymptomatic or pre-symptomatic people,

  • which is to say folks that are in the incubation period are spreading the disease,

  • and it may be much more than what we originally thought.

  • Viruses are given a reproductive number or R-naught, based on how quickly they spread

  • and person-to-person transmission has been confirmed both in and outside of China

  • an R-naught of 1 means that an infected person passes it on to one new person,

  • an R-naught of 2 means that one person spreads it to two new people, and so forth.

  • If the R-naught is below 1, the infection peters out,

  • if it's at one, it stays steady;

  • and if it's above one, then it continues to spread,

  • the current estimate for COVID-19 is an R-naught of 2.2.

  • As a point of comparison, the R-naught of the flu virus is about 1.3,

  • so COVID-19 spreads quite a bit more easily.

  • To confirm the diagnosis, a reverse transcription polymerase chain reaction or RT PCR test can be done

  • which can detect very small amounts of viral RNA.

  • It's worth mentioning, however, that early in the disease,

  • the RT-PCR can often miss the infection altogether,

  • meaning that it's not very sensitive,

  • so if severe pulmonary disease is suspected,

  • a chest CT should also be done to help detect the presence of viral pneumonia.

  • It's also important to look for other causes of similar symptoms

  • by doing things for example like a quick flu test,

  • or a respiratory viral panel to look for alternative causes of the symptoms.

  • Treatment is focused on supportive care,

  • such as providing fluids, oxygen, and ventilatory support for really ill people.

  • There's also early data showing that Remdesivir,

  • an antiviral drug previously used against Ebola can be helpful,

  • and it's being tested in large-scale clinical trials in the US and China.

  • Unfortunately, there's no vaccine currently available to protect against COVID-19,

  • having said that, there are some being researched

  • including one that is in clinical trials and will likely be ready by 2021.

  • So, the main goal is to avoid person-to-person transmission,

  • in areas with community transmission, anyone with mild symptoms,

  • regardless of whether they have been diagnosed as having COVID-19 or not

  • should wear a mask and they should self-quarantine within their home,

  • if those symptoms worsen, they should call their clinic or use telemedicine to talk to a clinician.

  • For people with symptoms that live with others or even with pets,

  • they should self-quarantine in a separate room and use a separate bathroom if possible

  • and they should avoid sharing household items like bedding or eating utensils.

  • In fact, there has been a confirmed case of human-to-dog transmission,

  • where COVID-19 went from a person to their pet dog.

  • however the dog didn't get sick,

  • and there's no evidence that pets can spread this disease or become sick,

  • so it's not necessary to take measures against companion animals.

  • Finally, anyone with symptoms including children and younger adults

  • should not attend school, work, or any other in-person gathering, and should avoid travel.

  • Now for individuals that don't have symptoms but are at higher risk like those over age 60,

  • and people with a chronic disease,

  • the recommendation is that they also self-quarantine to avoid the chance of getting sick.

  • Self-quarantining requires keeping a few weeks supply of your medications, groceries, & household items

  • as well as having an emergency contact person.

  • Coronaviruses don't usually spread over long distances in the air,

  • but they can get flung from one person to another on tiny droplets of saliva

  • when someone's coughing or sneezing.

  • In addition, some strains of coronavirus can survive on surfaces for over a day.

  • With that in mind, if you're a healthy person living in a non-outbreak area,

  • the recommendation is to avoid travel to disease outbreak areas,

  • generally stay away from crowded places and stay at least 6 feet or 2 meters

  • away from anyone with symptoms.

  • Wearing a surgical mask is not recommended

  • because they're meant to catch droplets from a cough or sneeze going out

  • rather than preventing you from breathing in the virus.

  • Similarly, wearing an N95 mask is not recommended

  • because they're only meant to be worn by healthcare workers.

  • In addition, cleaning and sterilizing frequently-touched surfaces

  • like toilet seats, door handles, phones, and keyboards is also a good idea.

  • As always, careful hand-washing is key,

  • and it should be done with soap or alcohol-based hand sanitizers and scrubbing for 20 seconds.

  • Also, avoid touching your eyes, nose, and mouth,

  • this is the area known as your T-zone, it's a common entry point for viruses into the body.

  • For healthcare workers who are around people with COVID-19,

  • the recommendation is to apply droplet and contact precautions,

  • that includes wearing personal protective equipment like a clean dry surgical mask,

  • gloves, long-sleeved gowns, and eye protections like goggles, or a face shield,

  • when performing a procedure that generates aerosol

  • like tracheal intubation, bronchoscopy, CPR, or non-invasive ventilation,

  • it's important to wear an N95 respirator.

  • This prevents 95% of the small particles like respiratory droplets from passing through.

  • Alright, as a quick recap, the SARS-CoV-2 virus causes COVID-19.

  • The virus travels in respiratory droplets and enters the body via the mouth, nose, or eyes,

  • it can cause symptoms like fever, cough, and shortness of breath.

  • And in some people, it can progress to more dangerous complications like pneumonia, ARDS, and shock.

  • The highest risk is among the elderly and those with other serious health conditions.

  • Treatments are focused on supportive care,

  • but medications like Remdesivir are in clinical trials,

  • and there's a vaccine in clinical trials as well that will likely be ready by 2021.

  • In the meantime, the best strategy is prevention,

  • this includes careful hand-washing,

  • avoiding traveling to disease outbreak areas, and crowded places when possible,

  • avoiding touching your T-zone,

  • and if you're a healthcare worker, using personal protective equipment.

By now, you've probably heard of COVID-19,

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B1 US covid disease naught fatality rate fatality transmission

COVID-19 (Coronavirus Disease 19) March Update- causes, symptoms, diagnosis, treatment, pathology

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    Amy.Lin posted on 2020/03/24
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