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!




Saturday, April 25, 2020

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

Hey Guys! Nice to see you again. I asked my Twitter followers for their questions on COVID-19 and got a lot of great responses. You guys are the best. This post is part one in addressing your questions.

@LaurenWhitticom asked:
Is it for sure going to become endemic?
          I think it will become endemic. There's no reason to think it will go away. Other coronaviruses that have found their way into humans have become endemic so I see no reason to think this will be different. If we want it gone, we would need a concerted eradication effort in every region. With such a powerful antivax movement in the US that's not going to happen anytime soon.

@MerryMary48 asked:
This is probably basic, but is there going to be a % of people who are just immune to this virus, without having had it?
          Not basic at all. It's a good question. And while we do not have data on this, I am confident in saying, not that there will be those who are naturally immune but that there will be those who are less susceptible to this virus than the general population. By this I mean that through as of yet unknown genetic mutations, there are likely people who can't be infected by this virus as easily. Maybe these are people with more cilia in their airways, or more robust cilia. Maybe someone has less ACE2 on the surface of their lung cells than the rest of us. There could be any number of places along the infection and disease development pathway where a mutation could confer the ability to more easily fight off this virus. I expect there are people like this in the world. Perhaps not many, but some. 

@mtw_ams asked:
I live on the ground floor with windows only to the street side with people passing by. Can the breath they exhale with virus infect me in my home?
          Considering the disparity of information being passed around, and the confusion regarding airborne vs droplets, I understand this is a concern for many people. Let me first say, the risk for you in the situation you describe is extremely low. I would feel comfortable leaving my windows open. Here's why. 
          In order to be infected not only does the virus have to survive in the air long enough under the conditions in the atmosphere to get through your open window from the sidewalk as someone passes by (sunlight, humidity, air currents), there must be enough surviving and infectious virus in the 'breath' that reaches you to actually initiate an infection. A person would have to really hack a huge cloud of virus, and that cloud would have to go immediately in through your window and into your nose/mouth to infect you. If someone is walking by that's unlikely. If someone is standing on the sidewalk facing your window as they cough, it's still unlikely. Distance is really your friend here, as are the air currents and ambient conditions. Unless we do a study outside your apartment to mimic someone coughing aerosols as they walk by, we can't say with 100% certainty that it will not happen, but it's highly unlikely to pose a real risk to you. 
          I would feel comfortable leaving my window open, but you may not and that's okay. Maybe you could put a fan by your window that's facing the sidewalk, so some air gets blown back out or a current is generated reducing the amount of outside air coming inside. Alternatively, you could put a sign next to the sidewalk that says something like - COVID patients inside, must leave window open, please cross sidewalk before passing. That should keep people away from your windows. 😏

@KenVaughanSoc asked:
How is touching my face unsafe, but putting food prepared by others in my mouth isn’t?
          Touching your face with contaminated hands can expose the parts of your face most susceptible to virus you've picked up from contaminated surfaces - doorknob, gas pump, elevator button - by touching your nose or mouth leading to exposure in the lungs. For that to be a risk, someone infectious had to contaminate the surface you touched. When you eat food prepared by someone else, the risk of that is lower. People prepping food should be wearing masks, which will protect the food from contamination, if that person is infected, which they likely are not if they are prepping food. In addition, food being chewed then swallowed is forcing particles in your mouth into your stomach and away from your lungs. This reduces the potential for virus to make it to your lungs in the rare instance it might be on your food. In your stomach this virus can't survive the acid. Before you eat your food, you will have touched the packaging. To be on the safe side, wash your hands before you eat. If you'd like more assurance, ask the business if those prepping and packaging food are wearing masks, if any of their employees are being forced to work while unwell, or if anyone employed there has been sick with COVID-19. 

What is the consensus on face masks and why was there so much debate amongst scientists early on regarding their use for the general public?
          Ah, face masks. A confusing and never-ending battle. Initially, scientists, including myself, were trying to convey how dangerous it was for an untrained person to wear a respirator that was not fit-tested. For example one they bought online. This is because we knew it would give people a false sense of security. Not only would the mask not truly protect you from exposure to someone coughing near you, but taking off a contaminated mask is a common source of infection for people who are not trained to do so. We were also trying to convey the difference between surgical masks (and folded t-shirts and bandanas) and N95 respirators. Surgical masks are designed to protect people from the wearer. N95s are designed to protect the wearer. So while some people, mostly non-scientists, were yelling at people to wear masks, we were trying to convey the differences between the masks, the differences between when they are needed and how they really would and would not protect you. Here is an image that really illustrates what's happening with masks. I saw it on Twitter shared by Don Jazzy don't know if that's the original source.
          We have reached the point where public health leaders are recommending face masks for everyone going out in public. This is because, in places that did not get ahead of the epidemic through testing and contact tracing early, we have no idea who is sick and infectious. It's important to understand that this recommendation is still to protect people people from the wearer, not to protect the wearer. But the bonus here is that if everyone wears a mask then no one has to understand anything. I'm protecting you from me and you're protecting me from you. Who cares if someone thinks it's the other way around if we're both being protected.
          But don't forget that touching the mask can contaminate your hands, or your chin if it's been contaminated. So drop it straight into the trash or washer, wash your hands immediately, and use a new/clean one the next time you go out.

@The_Twenty_Two asked:
How much are you worried about surface to human transfer?
          Contaminated surfaces, called fomites, are a definite risk with SARS-CoV-2. A research letter documenting apparent fomite transmission in China, I think did a great job evaluating this risk while still recognizing the limits of their work. A more recent and well executed, rigorous study indicates the virus can remain alive and able to infect longer than we would have expected under their conditions. However, every time someone touches a contaminated surface, they wipe some virus off, so the last person to touch that surface won't get as much virus on their hand as the first person. This is why washing hands has been urged from the beginning. It's also why gloves aren't necessarily better than hand washing. I see people in stores wearing gloves and touching everything, as though wearing gloves means they no longer have to be careful. If they get virus on their gloves, they then transfer it to their credit card or wallet or mask, or head or even face. I don't wear gloves at the grocery store just like I never wore gloves when SCUBA diving. Gloves make you feel like you can touch anything. While diving that damages the living things you feel compelled to touch, during a pandemic it increases your risk of infection. Touch only what you absolutely must touch and force yourself to think about not touching anything else, like your face. As soon as possible disinfect/wash your hands thoroughly.
          As for things like packages left at your door, food delivery bags/boxes or grocery bags. If those are prepared by people without symptoms then there is very little risk. Use the same caution: handle the items only as much as needed and discard. Then wash hands thoroughly with soap and water.

@goatbroken asked:
I heard a rumor that the flu shots might interfere with the body's ability to fight other corona viruses... is this credible?
          I have not come across anything credible supporting this. The paper you asked about, "Influenza vaccination and respiratory virus interference among Department of Defense personnel during the 2017–2018 influenza season" by Greg G. Wolff, does not provide evidence for that theory. Some studies describe the phenomen of vaccine-associated virus interference: that vaccinated people may have increased risk for other respiratory viruses. Their logic is that it's because vaccinated people do not get the non-specific immunity associated with natural respiratory infections. 
          There is contradictory evidence regarding this idea in general, and contradictory evidence that the influenza vaccine is associated with it. I haven't seen anything that convinces me that this happens. In the linked paper, the study was rigorous: it's the "first virus interference study conducted among highly vaccinated DoD personnel. The study included a diverse, well dispersed population based on sex, age group, beneficiary category, and vaccination status." the results "showed little to no evidence supporting the association of virus interference and influenza vaccination." In fact they showed that "those receiving the influenza vaccine were more likely to have no pathogen detected and reduced risk of influenza when compared to unvaccinated individuals." This further supports my opinion.
          On a related note, a really interesting study on influenza vaccination came out last year by a group at UT Austin. This was a study on the persistence of antibodies from influenza vaccines over time. They found that the antibodies generated by the yearly vaccine are relatively short-lived and that once they are gone, the remaining antibodies are a group that has persisted over time - a group of antibodies against the parts of the influenza virus that are not usually mutated. So in addition to the antibodies we have from the vaccine, we also carry antibodies we've had for years against various parts of the virus. Previous exposure and vaccination thus work synergistically with the yearly vaccination to protect us. The coolest part of this is that it provides insight into potential vaccination strategies previously thought not worth pursuing.

That's it for Part I. I hope it's been helpful so far. If something wasn't clear enough please let me know so I can improve my answer for you. If your question isn't here, it will be posted ASAP. Thank you for your patience! And thank you for the questions. No doubt they will be helpful for many others.

Stay home and wash your hands,