Questions & Answers

Can the virus multiply outside of a host?  And if so, under what conditions?

Viruses are not classified as living organisms because they cannot reproduce by themselves.  The only way they can multiply is by taking over another cell (such as cell that is part of the lining of the airways) and forcing that cell to make more viruses. Therefore, the virus cannot multiply outside of the host.

 Scott Filler, MD, 5/7/2020


Is there any theory of length of exposure time in sun necessary to reduce infectivity of COVID-19?

The ultraviolet rays from the sun can inactivate the virus, but people can still contract the virus outside in the sun.

 Scott Filler, MD, 5/7/2020


I'm hearing a lot about the anti-body tests? What is that and do they work?  

The tests check to see if a person has developed an immune response against the COVID-19 coronavirus, a finding that may suggest that the person has had a COVID infection. The current antibody tests have both false positive and false negative results and are not recommended for general use.  Their only utility is to track the prevalence of the infection in different populations.

 Scott Filler, MD, 5/7/2020


Have you seen more information on collateral effects of the virus, specifically the incidence of "COVID toes" and what is the understanding of what to do if one encounters those symptoms?

Although the most prominent symptoms of COVID-19 are respiratory symptoms together with fever and headache, the disease may cause impairment in other organs including brain, heart, kidney, liver and skin.  This impairment may be due to virus-induced injury or be a consequence of an uncontrolled immune response against the virus (the "cytokine storm").

Lesions similar to chilblains have been described in COVID-19 patients, mostly in toes (so-called "COVID toes").  An initial study reported that 19% of COVID-19 patients had chilblain-like lesions.  However, the link between COVID-19 infection and these lesions is still unclear. It is possible but not yet demonstrated, that the virus and/or the immune response to the virus could cause these lesions. 

Most of the patients with confirmed COVID-19 and chilblains-like lesions have mild cases of the disease.  It is prudent to recommend testing for COVID-19 if a person has "COVID toes", especially if other symptoms such as fever and headache are present.

 Joaquin Madrenas, MD, PhD, 5/5/2020


How do pandemics end?

 Joaquin Madrenas, MD, PhD, 4/18/2020, during an interview with Shamiram Media


What is contact tracing? Could it help limit the spread of COVID-19?

Contact tracing is a concept used by Public Health agencies, hospitals, and other medical systems to locate persons who may have been exposed to a certain transmissible infection. It is very useful for tracking uncommon contagious infections like measles and tuberculosis so that persons can be tested, counseled and/or treated, as appropriate. For COVID-19, however, it is relatively widespread in the community and, at this point in time, contact tracing would consume an inordinate amount of resources. Furthermore, sometimes it's very difficult to know "who exposed who" if people have extensive contacts. It is only used being in selected situations, mostly group living facilities like nursing homes and correctional facilities. If COVID-19 becomes rare, contact tracing may indeed have a role.

 Loren G. Miller, MD, MPH, 4/15/2020


I may have had COVID-19. Is there a test or one coming so I can know for sure?

There is a test to see if you have had COVID-19 infection in the past and have recovered. The test is called a "serologic test" looking for your antibodies, i.e., proteins that are part of your immune system, that tell you if your body's immune system has seen and fought off COVID-19 infection. Unfortunately, these new COVID tests (as of April 11, 2020) are extremely difficult to get and, currently, largely being done for research purposes, so we can better understand who has had COVID and how accurate this test will be. Most experts believe this test will become increasingly available over time, although when it will be available to most persons is difficult to predict.

 Loren G. Miller, MD, MPH, 4/11/2020


It seems that there is evidence to suggest that if one were to become symptomatic, it would be it advisable to take Tylenol, rather than Advil/Ibuprofen.  Is this the current recommendation?

The evidence about NSAIDs (like Advil/Ibuprofen) and COVID-19 is equivocal.  It is not clear whether they have any effect on the outcome of infection. However, if given the choice between taking an NSAID or Tylenol for symptoms related to COVID-19, I would take Tylenol.

 Scott Filler, MD, 4/9/2020


Now that we know that we should indeed be wearing masks when out in public, whether to protect others from asymptomatic transmission, ourselves, or both, would it also make sense to wear some form of eye covering, glasses, etc.?

While the virus that causes COVID-19 can cause infection by touching the eye, it would take a sneeze or cough or other respiratory droplet from another infected person hitting the eye to cause infection. Remember: droplets from sneezes, coughs, and talking from an infected person's mouth only travels about 3 feet before they fall to the ground with gravity. There are easier ways to protect yourself from these droplets than wearing eye protection:

  1. maintain social distancing of 6 feet or more from others, and
  2. don't touch your eyes, inside of your nose, or mouth unless you have done good hand hygiene first.

Good hand hygiene is at least 20 seconds of washing with soap and water or use of an alcohol-based hand rub containing at least 60% alcohol.

 Loren G. Miller, MD, MPH, 4/7/2020


Is there a possible correlation to the amount of virus to which one is exposed and the severity of disease development?

It is not clear. Usually there is a minimum viral amount called the "infectious dose" that a person has to be exposed to to acquire infection. Each infection has a different "infectious dose" and the dose of the virus that causes COVID-19 is unclear at this time (as of April 2020). Based on other viral infections, there may not be a relationship between amount of virus to which one is exposed and severity of disease development. However, what is clearer is that certain persons who get an "infectious dose" of the virus that causes COVID-19 are at higher risk for severe disease. These persons include older persons, those with immunosuppression (weakened immune systems), and obesity.

 Loren G. Miller, MD, MPH, 4/7/2020


Does sunlight have any effect on coronavirus longevity?

Because it is a virus, the COVID-19 coronavirus is not actually living. Studies to detect its presence usually test for the amount of viral RNA. It is not currently known how well the presence of coronavirus RNA correlates with infectivity, but it is generally felt that the larger amounts of RNA are associated with increased infectivity. The ultraviolet rays in sunlight are known to break down RNA, so it is highly probable that sunlight reduces the longevity and infectivity of the COVID-19 coronavirus.

 Scott Filler, MD, 4/6/2020


Some people who have COVID-19 are dying from a cytokine storm, an overreaction of the immune system, not the disease directly. What exactly is a cykotine storm and how can you die from an overreactive immune system?

Cytokines are small proteins that attract and activate white blood cells. White blood cells make a variety of toxic substance that normally kill microbial pathogens, such as viruses, bacteria, parasites and fungi. In patients with COVID-19, it is thought that there is overproduction of proinflammatory cytokines in the lungs.  As a result, high numbers of white blood cells are recruited to the lungs. Due to the high levels of cytokines (the “storm”) in the lung, the white blood cells are stimulated to overproduce these toxic substances and actually kill the lung cells.

 Scott Filler, MD, 4/2/2020


What is meant by the concept "Herd Immunity" and how will it affect the pandemic?

Herd immunity is a state of resistance to an infectious disease for a given population.  This state can occur either because of vaccination to the members of that population or because of exposure to the infectious disease of a number of individuals in that population.  The basis of herd immunity is the interference with the spreading of the infectious agent, for example a virus, by individuals that are already immune to the infection by that virus, and therefore make contagion less likely.   
How many individuals within a population need to be immune to that virus to stop the spreading of the disease depends on how contagious the virus is.  The more contagious the virus is, the more people immune to that virus are needed to have herd immunity.  For example, measles is highly contagious and requires that 90% or more of individuals be immune to measles (because of vaccination or having had measles) to have herd immunity.  Initial estimates for COVID-19 suggest that around 60% of people immune to the virus that causes COVID-19 may be required to build herd immunity and stop the spreading of the virus.
The problem of relying on herd immunity to stop COVID-19 is that, in the absence of a vaccine, the development of herd immunity for the virus relies on people having had the disease to become immune to the virus.  This is risky given the serious effects that COVID-19 can cause and the mortality associated with it.

 Joaquin Madrenas, MD, PhD, 4/2/2020

What is your opinion regarding safety factors on the malaria drug being used as an emergency drug for COVID-19 patients considering the following facts below, and I quote, "In a statement, HHS reiterated the drug still only has anecdotal evidence to support its efficacy. Anecdotal reports suggest that these drugs may offer some benefit in the treatment of hospitalized COVID-19 patients. Clinical trials are needed to provide scientific evidence that these treatments are effective."?

A short course of hydroxychloroquine, such as what is typically given to patients infected with COVID-19, is generally safe. However, it should not be given to patients with certain findings on their EKG because it increases the risk of cardiac arrhythmias. 
At present, there is very limited data about the effectiveness of hydroxychloroquine. Although many clinical trials to test the efficacy of hydroxychloroquine in patients with COVID-19 are ongoing, the results of these trials are not yet available.

 Scott Filler, MD, 4/1/2020


Is food takeout and delivery safe?

Food delivery is believed to be relatively safe and the risk low, but because there are still theoretical risks, it's best to remain vigilant about cleanliness and hand hygiene when receiving takeout food.

As far as the food itself, the CDC and FDA notes that coronaviruses are generally thought to be spread from person-to-person through respiratory droplets. Furthermore, there is no evidence to support transmission of COVID-19 from food.

However, the food packaging could in theory be contaminated if an infected person who handled it if the person packing the food was infected and didn't use good hand hygiene. The good news is that the you can do things to protect yourself from this small risk. After handling any packaging the food comes in and opening the food containers, do good hand hygiene with soap and water for at least 20 seconds. Use clean utensils to pick up any food. Clean any surfaces that the packing came in contact with household cleaners, or soap and water, as you are cleaning up.


 Loren G. Miller, MD, MPH, 4/1/2020


What is convalescent serum?

COVID-19 convalescent serum, or better named convalescent plasma, is plasma from patients that have recovered from COVID-19.  The idea is that this plasma will contain antibodies that may be protective against the infection.  A similar approach has been used with other viral infections, including some caused by coronaviruses, but the results are non-conclusive.

 Joaquin Madrenas, MD, PhD, 3/31/2020


I learned yesterday that there has been a recent study, done by MIT, that suggests that the currently recommended “social distancing” of 6.5 feet is not sufficient.  Can you provide any information about this?

Our current understanding is that under normal circumstances in the community, the virus can only travel as far as someone can sneeze, cough, or breathe. This is called "droplet spread". Droplet spread also means that the virus does not waft in or remain in the air. Thus, after an infected person coughs, sneezes, or breathes, the droplets fall down due to gravity and land on other surfaces below or on the ground. Only in extraordinary circumstances under highly pressurized airflow, typical only in medical procedures done in hospitals, can the virus travel further.

 Loren G. Miller, MD, MPH, 3/30/2020


Is it possible for COVID-19 to circulate through the air conditioning vents in buildings?

The virus that causes COVID-19 should not be able to travel through air conditioning vents. Most viruses cannot waft in the air. After the virus is coughed or sneezed out through droplets from the infected persons nose or mouth, the droplets that contain virus fall to the surface below or to the ground through gravity. The virus does not remain suspended in air without extraordinary efforts and highly pressurized airflow, which are typically seen in hospitals with specific medical procedures.

 Loren G. Miller, MD, MPH, 3/30/2020


I have heard that certain blood types (O?) may be more resistant to COVID-19.  Can you provide any information on this?

In a non-peer reviewed preprint from China, it was reported that people with “blood group A was associated with a higher risk for acquiring COVID-19 compared with non-A blood groups, whereas blood group O was associated with a lower risk for the infection compared with non-O blood groups.” However, these data are preliminary and have not been confirmed.

 Scott Filler, MD, 3/29/2020


How is the coronavirus different from the flu?"

Coronavirus is more contagious than the flu because no one appears to have pre-existing immunity to coronavirus, whereas many people have pre-existing immunity to the flu.  Also, it is estimated that the mortality associated with coronavirus is about 10 time greater than the flu.  Another key difference is that there are currently well-established vaccines and anti-viral drugs against the flu, whereas there is currently no vaccine against coronavirus and all potential treatments for coronavirus are experimental and of uncertain efficacy.

 Scott Filler, MD, 3/29/2020