This post will attempt to answer the following questions:

  1. Why is COVID-19 so dangerous?
  2. Why are people losing their sense of smell?
  3. Why are people dying suddenly?
  4. How do I stay safe if I am infected?

I’ve been working in the hospital recently as a consultant for pulmonary issues. This means that when the main hospital doctors have questions about issues related to a patient’s lungs (including issues with low oxygen) they call me to offer advice. What that has meant in the last few days is that I’m seeing only patients with COVID-19.

There has been a very interesting phenomenon described by physicians around the world caring for patients with COVID-19. The virus causes a syndrome that is unlike just about any other disease that we are used to seeing. I think this is best illustrated with a patient I saw yesterday. She has underlying lung disease but was otherwise healthy and active. She developed symptoms of COVID-19 about 3 or 4 days before being admitted to the hospital. She came in because she had persistent fevers. In spite of high fevers she never had significant shortness of breath and was only requiring a small amount of oxygen. A few days after she was admitted and about six days after she developed symptoms she had a sudden rise in her temperature. She also had worsening of blood tests that are a sign of an increase in inflammation in the body. I looked at her numbers in the computer and expected to walk in the room to see somebody it was terribly ill.

What I saw was quite the opposite. She was sitting in her bed smiling with no shortness of breath. She decided to take off her oxygen because she didn’t feel she needed it. I put the oxygen sensor on her finger and was quite concerned when I as that her oxygen saturation was 81% and she was breathing about 35 times a minute (normal is 12-16). A saturation of 81% is extremely low and life threatening. In spite of such a dangerously low oxygen she barely had symptoms.

Her story is not unusual for this infection. In a previous post (How the coronavirus makes you sick) I explained how different viruses are designed to target different parts of the body and that the SARS-CoV2 virus impacts specific cells in the respiratory tract which accounts for the lung disease it causes. As more research has been done it has been discovered that the virus also has what is called neurotropism. What that means is that it has the ability to infect nerves as well. This accounts for the unusual symptom people are experiencing where they lose their sense of smell. It turns out the virus can directly affect the olfactory nerves. These are the nerves that are responsible for your sense of smell. Another set of nerves that it can affect are the nerves in the brainstem that are responsible for regulating cardiac function. This is believed to explain the reason why some people with COVID-19 her dying suddenly of heart arrhythmias.

The impact of the virus on the nervous system also explains why the lady above had dangerously low oxygen levels with evidence of severe inflammation and no significant difficulty breathing. The virus can affect part of the brain which is responsible for triggering the sensation breathlessness. This sensation normally acts as a warning system to let you know that something is wrong and that you need to rest or seek medical attention. In a minority of patients with COVID-19 there is a period usually 5-7 days after symptoms where there is a massive increase in the inflammatory response leading to rapid deterioration. While this is happening, however, the virus is also suppressing the sensation of breathlessness and people are unaware that they are so ill.

As an example there was a lady in our ICU over the weekend who went from being on a very small amount of oxygen and texting her friends to being on a respirator over a period of a few hours.

Another example of why this is so dangerous came last week. I got a phone call from another patient’s wife last week asking for advice. Her husband was sick with COVID-19 and she was taking care of him. He had had persistent fevers which did not seem to be subsiding. On the 6 day of his symptoms he started having low oxygen levels. She, being a nurse, arranged for him to get a home oxygen machine. In spite of the getting supplemental oxygen his oxygen levels remained low. She was afraid to take him to the hospital because of what she was seeing on the news about the hospital being over run and people not getting adequate care. She was planning on keeping him home and adjusting his oxygen herself. I was concerned for all the reasons I mentioned above and told her to take him to the hospital immediately. He was on a respirator a few hours later. Had he been home and deteriorated as he did, she likely would have not been able to get him to the hospital in time and he would not survive.

The reports from New York and before that from Italy are concerning. The mortality rate that is reported in the news is certainly an underestimation. People are afraid to go the hospital and are dying suddenly at home likely for the reasons I have told you. They have severely advancing disease without significant symptoms but then rapidly deteriorate or have cardiac involvement and die suddenly. Since many of these people are dying at home they are not being tested for the virus and are not included in the death numbers. I worry that many of these people decided on their own to stay home and may have been saved.

So how can you stay safe? Keep in mind, the majority of people with COVID-19 still have mild disease and will not need hospitalization. If everybody with the disease goes the hospital will exacerbate the problem. On the other hand, it is clearly safer to be in a hospital (even with all the problems you see on the news) if you have severe disease. This is because you are closely monitored and can get high levels of oxygen or can be put on a respirator if you deteriorate rapidly. If you are at home you may not recognize your deterioration until there is not enough time to get taken to the hospital.

To protect yourself, this is what I would recommend:

  1. If you have underlying heart disease, lung disease, obesity, a compromised immune system, or advanced age and are infected you should go to the hospital if you feel shortness breath. I would strongly recommend that you purchase a pulse oximeter. These are small sensors that can be put on your finger and measure your oxygen levels and heart rate. They can be bought online or at drug stores. You should check your oxygen level regularly and go to the hospital if you have a reading that is 93% or less or if your heart rate is over 110 measured after sitting down for a few minutes.
  2. If you do not have underlying medical conditions and are under the age of 60 I recommend going to the hospital if you have severe shortness of breath. But I would also recommend buying a pulse oximeter if your fevers persist for more than 5 days. You should then follow the same instructions as in recommendation #1.
  3. Once you have recovered, it would be wonderful if you could then donate your pulse oximeter to people who do not have access.

Just so you don’t panic, people who have zero symptoms are not dying suddenly. The people who are unaware of their low oxygen levels are sick they just don’t realize how sick which is how the oxygen sensor is helpful.

The virus is causing a surreal experience both in terms of how it affects the body and how it affects society. My motivation is to keep people safe and help save lives. Please spread this around to help me with that goal. Many of the people who are dying at home are dying not just from the virus but from ignorance of how it affects the body. Please help me fix that. Tell everyone you know.

13 thoughts on “You may be dying of COVID-19 without knowing it…

  1. Thank you for continuing to inform us. I had ordered a Pulse Oximeter last week. Thanks for confirming I wasn’t crazy for ordering it.Sent from my Verizon, Samsung Galaxy smartphone


  2. I have been taking hydochloroquine 200 mg 2x daily for Rheumatoid Arthritis for approximately 2 years.. I am curious if you have heard if it works prophylactically against getting the virus or in fact, if I did get exposed,that I would have some “protection “ against being infected or would possibly get a milder case.


      1. Thank you for taking the time to write your blog. It has helped keep me more calm and level headed over the past months. I have lupus and I am on plaquenil. Thanks for the glimmer of hope. One of my concerns is that I also have Raynauds and pulse oximeters NEVER works on me, I think because my fingers are always purple. Even when I’ve had small procedures, they have had to clip to my ear or tape to my forehead to get a proper reading. This scares me. Any advice?


  3. Thank you for a very informative article. I am in my mid sixties. I have had a dry cough now for about 5 weeks. About 2 weeks after the onset of the cough I had one week of mild fever of around 100 degrees with 1 day of 101 degrees. I had lost my appetite (not so much my smell) and was sleeping a lot. I was tested for the Covid 19 in the middle of that week at Sinai parking lot with a swab stuck in my nose. Ten days later, when I already felt much better, I got the result which was negative. What is the probability that it could be a false negative? I am now 2 weeks without a fever but I still have a dry cough and no shortness of breath. I am a dentist and though I feel back to myself, I worry that I could still possibly be a carrier. How can I eliminate this doubt? Should I get myself a pulse oximeter? Can I now go to the supermarket with a mask?


    1. It is not yet clear what the false negative rate is but seems to be up to 30% so it is quite possible you had COVID-19 but had an incorrect result. You have almost certainly recovered. The fact that you are still coughing does not mean you are still actively infected. A cough can persist after any viral respiratory infection for several weeks. The only way to know for sure that you were infected would be to get antibody testing which is not yet available widely. Even though you were likely infected and now immune it is safest to assume you have not been infected and go out with a mask and wash your hands frequently.


  4. I am a 71 year old woman in good health, ( except for controlled hypertension)who has self- quarantined for the past four weeks. During this time, I have not even gone to any grocery stores, and have only left my home to go for daily walks. I have not experienced any of the corona virus symptoms.
    With all the talk now about resuming normal life, testing for those who have had, or think they’ve had the virus, I’m wondering what the best course of action for re- entry should be for people like me who have been social distancing to avoid contracting the virus?


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