Monday, April 27, 2020

Pandemic 2020: COVID-19 Questions From My Tweeps: Part II

Welcome back guys! This is Part II in my series answering questions about COVID-19 asked by my wonderful Twitter followers. Let me know if you have follow up questions or if anything is not clear.
@steadywind and @slava_m asked:
Is their immunity after COVID-19 and if so how long would it last?
          Based on what we know of other disease-causing coronaviruses, there will be some level of immunity following infection with SARS-CoV-2 and COVID-19 disease. What we still don't know is how long that immunity will last. Coronavirus experts agree that Coronaviruses don't induce long-lasting immune memory like other viruses often do, but evidence indicates recovery will offer strong protection for a bit (~1-2 years) and some protection after that. No doubt some people with less robust immune systems may get reinfected later in the absence of a vaccine. This is expected and we shouldn't freak out. It means we need a vaccine and until we have one, we need to be vigilant, especially with regard to those most vulnerable.

@JahodaLubos asked:
Whats more probable in the short term:efficient therapeutics and treatment plans or vaccines?Can therapeutics facilitate a return to “normal”?
          In the short term we need therapeutics and treatments simply because it is going to take at least a year before we might have an effective and safe vaccine. Likely it will be longer. This is why getting transmission of the virus under control and flattening the curve are so important. It gives our health care systems time to catch up. While therapeutics would be helpful, having an effective therapy would not mean we could just get back to normal. The steps along the path to treating a COVID-19 patient each have their own limitations. For example, to treat someone we would have to have a verified diagnosis. Right now, global demand for test components far exceeds manufacturer's output abilities. Once a therapy is found effective and approved, it too would need to be manufactured and distributed worldwide. Unless we control the spread of the virus, global demand for the treatment would also quickly outpace production capability. Of the many potential treatments tried so far, none have been shown effective against this virus. Scientists are working around the clock to develop therapeutics and vaccines, let's support them in their efforts by doing what we can to slow down the spread of this virus. 

@DeanneB57530417 asked:
What are the anticipated / possible mid to long term health consequences for those who ‘recover’ from Covid-19? And are these being monitored?
          The information we have on this so far comes from physicians reporting what they see in patients. Currently we don't have a database on this but as we move forward this will be something we have a better handle on. Physicians report that those with mild symptoms are expected to make a full recovery, and that's what they observe. Those with more severe disease are at risk for long-term sequelae (a condition caused by a previous disease or injury). So far, observations indicate that permanent damage from COVID-19 can happen to the lungs, kidneys, and heart.
          In the lungs, an exaggerated immune response can trigger a disease process leading to pneumonia, secondary bacterial infection, and increased virus replication. This takes a toll on alveoli in the lungs and can cause irreversible damage to these little sacs that exchange oxygen and CO2 with the blood. Those with lungs that are aged, less elastic, or more susceptible to inflammation already, will have a greater risk of severe disease, and sequelae or death. According to physicians I spoke to, about 15% of those infected will get severe disease and pneumonia. Pneumonia usually doesn't cause long-term problems but pneumonia in COVID-19 can be more severe. It could take people up to six months to recover from the associated breathing difficulties. About 20% of those who develop pneumonia will progress to the alveoli-compromised stage of the disease that results in respiratory failure. Those severely affected by the disease who recover could have breathing related issues for life, the severity of which would depend on how much damage/scarring occurred. For those with the greatest damage, normal breathing may never return. For the rest of their lives they may get short of breath with minimal exertion or require medication to help them breathe.
          The kidneys are also at risk for permanent damage in those with severe COVID-19. In order for kidneys to function, they need fluids and the right amount of fluid pressure. Doctors must carefully balance fluid and pressure to the kidneys while not adding additional fluid burden to the lungs. Those who survive severe COVID-19 will need their kidney function monitored to check for permanent damage.
          Doctors are also seeing cardiac problems with COVID-19 patients. While SARS-CoV-2 can infect cardiac cells directly, causing inflammation of the muscle and heart rhythm problems, the disease the virus causes can also affect the heart. When COVID-19 reduces oxygen levels in a patient, that puts extra stress on the heart as it works harder to oxygenate the body. As expected, those with pre-existing cardiac problems are at greatest risk of severe cardiac presentations. Direct infection of cardiac cells can also cause catastrophic cardiac inflammation in the absence of pre-existing cardiac problems. The heart muscle can be severely damaged, reducing the heart’s ability to pump blood, which can be fatal even in the healthy. If one is lucky enough to survive severe COVID-19 with cardiac damage, cardiac function will need to be carefully and regularly monitored.
          Other organs can suffer damage from lack of oxygen during COVID-19 including the liver and brain but as of now I've not seen data on long-term effects other than death caused by multi-organ failure. No doubt we will learn more on each of these as time passes.  

@isaberchtold asked a related question:
Undetected Patient with mild symptoms with huge lung damages. Is it really irreversible?
          Yes, it's possible to experience significant lung damage while displaying mild symptoms. Interestingly enough, physicians are describing patients with dangerously low oxygen levels with no overt breathing difficulty. They call this silent-hypoxia and it transitions quickly into respiratory failure. As the alveoli are compromised and oxygen levels drop, the lungs can remain 'compliant' allowing patients to expel CO2. When CO2 doesn't build up, there is no sense of being short of breath. These patients eventually have trouble breathing and go to the hospital but their O2 levels are already so low, many are in serious distress and need ventilators. When this happens, it's more likely that the damage caused to alveoli will be irreversible. One recommendation to help prevent this scenario is to use an over-the-counter pulse oximeter to measure your O2 levels at home. This painless device passes small beams of light through the blood in the finger, and measures changes of light absorption in oxygenated or deoxygenated blood. If your O2 level falls below a certain threshhold, whether you have other symptoms or not, you would need to seek medical care.

This leads into the question from @bryangrahn who asked:
Do you think lung surfactants could help people with serious lung damage?  Are you aware of any clinical trials for this treatment?  Are synthetic or natural surfactants a better option for adults - and are either scalable if they do work?
          First, I'll describe pulmonary surfactant for my readers who aren't familiar with it. A surfactant is a substance that reduces the surface tension of the liquid it is dissolved in. In the lungs, epithelial cells in the alveoli secrete a pulmonary surfactant to lower the surface tension of the water within all alveoli. By reducing that surface tension, the surfactant makes it easier for the alveoli to reinflate after exhalation and helps prevent airway collapse. Without enough surfactant, your alveoli won't work well and can end up damaged leading to a collapsed lung.
          Considering that SARS-CoV-2 attacks the cells that make surfactant in the lungs, it seems reasonable to think that treating lungs with surfactant might help. After looking into this, it appears that while this might be worth trying, there have been no exogenous surfactants developed that are able to reduce surface tension enough to make a difference in these patients. Thus, there are currently no efforts to use an exogenous surfactant as therapy in COVID-19 patients. 

Thank you all for your questions! Part III coming soon!




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