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Updates to COVID FAQ August 1st, 2020

I’m struggling to stay on top of adding recent research results to the blog (while also getting ready to teach this fall and manage other responsibilities), but I did manage to add a few items (see

  • A new FAQ question about the various medications and treatments available for COVID-19
  • A new study on virus levels in the upper respiratory tract of children

Updates to COVID-19 FAQ July 18th, 2020

I’ve made the following updates to the COVID-19 FAQ:

  • More detail in comparisons between COVID-19 and flu fatality rates
  • A citation documenting a potential long-term effect of COVID-19 on male fertility
  • More detailed information on the risks of SARS-CoV-2 in children including an estimate of the mortality rate (less than 0.1%) and a range of reported ICU needs among children (0.6%-2%).
  • Additional links to articles that address two pieces of misinformation about masks that I’ve encountered (a miscommunicated scientific article and a forged CDC letter)
  • A link to a video from PBS discussing the science of masks and showing a visualization of how masks influence emission of particles (
  • An example of a recent outbreak of COVID-19 that appears to have been spread by a young child at a daycare, calling into question previous reports of limited spread by children. The evidence on this topic is currently far from conclusive.

Updates to COVID FAQ

I’ve just added some updates to my COVID-19 FAQ, including:

  • Specific estimates of infection mortality rate (often 5 to 10 people per 1000) with links to sources.
  • More information on risks of COVID-19 to children, with more citations. Notably, although most children do not experience severe symptoms and very few die, up to 40% of children who contract the disease may experience moderate symptoms including pneumonia. Risks tend to be greater among infants and those who are immunocompromised.
  • New information about risks of spread of SARS-CoV-2 infections among children. Notably, spread appears to be much more common among children older than 12, whereas children younger than 12 most often get it from an adult rather than from other children their age. But this is based on very limited and preliminary evidence, so extreme caution should be taken in using this information to make widespread policy decisions.


Kevin McCluney’s COVID-19 FAQ

I am a biology professor and active researcher (i.e. a scientist;, but I am not a microbiologist or an infectious disease or public health expert. However, I have been trying to keep abreast of the latest peer-reviewed publications and the best science communication and news articles related to SARS-CoV-2 (the virus causing the COVID-19 disease in adults and the MIS-C syndrome in children). My training as a scientist and biologist and my background in statistics can help me interpret these peer-reviewed scientific publications, even if they are not directly in my own sub-discipline (ecology). However, because I am not trained specifically as an infectious disease expert, there may be things that I don’t fully understand. Despite this limitation, others have been coming to me for advice, often as the only scientist/biologist they know. And I feel a responsibility to do my best to help dispel myths and educate and inform. So I decided to curate a collection of links to articles that address a number of frequently asked questions about SARS-CoV-2 that I believe are causing a lot of confusion.

I will be updating the FAQ as new studies are published and our understanding of the topic changes. Note that this is different from the approach taken by the CDC and WHO, who often wait for a high level of confidence in the published research before changing their recommendations. In general, their approach is a good one, but personally I believe that recommendations need to be more dynamic in a time of crisis management. This belief is partly based on my familiarity with the sub-discipline of Conservation Biology, which is a crisis-based science. When concerned about endangered species, management decisions sometimes need to be made with imperfect information because waiting for perfect information might lead to extinction. Similarly, we are currently living through a global pandemic and as such, I think it is important that we consider what research suggests on a topic, even if there are only 1 or 2 studies on that topic.

I note that I would love feedback, especially from experts in infectious disease, in case I am misinterpreting something.

Each question below contains a short summary of my personal opinion of what is indicated by the available research and then links to that research, as well as some articles written by science journalists, interviews with experts, or blog posts by experts. At some point I may try to summarize each article individually, but I have not yet done that. Many of these articles are open-access, but if you need access to one that is not available, feel free to email me and I’ll send you a copy.

Table of Contents

1.     Is COVID-19 really that bad, or is it just sensationalized media reports? Is it any worse than the flu?

2.     I’m young and healthy, so I don’t need to worry, right?

3.     But it doesn’t affect kids, right?

4.     But masks don’t really work, right?

5.     But as long as I stay 6 ft away, I don’t need a mask, right?

6.     What activities place me at the most risk for infection of SARS-Cov2? How can I reduce my risk?

7.     I already had it and recovered, so I’m immune, right?

8.     I was exposed, but my test came back negative, so I’m safe and don’t need to quarantine myself, right?

9.     But I heard that masks lower your oxygen levels and hurt your immune system.

10. But children don’t spread SARS-CoV-2, right?

11. But there are effective medicines or cures, right?

12.       Additional Resources.

1.      Is COVID-19 really that bad, or is it just sensationalized media reports? Is it any worse than the flu?

  • Although the mortality rate varies from location to location due to underlying health and age of the population and variation in medical treatment, and there is still a lot of uncertainty about the exact value, the overall infection fatality rate for COVID-19 appears to often be in the range of 0.5-1% (5-10 people die for every 1000 infections), which is 5-10x times higher than the typical flu (0.1% or 1 death per 1000 infections). Over 137,000 people (July 13th, 2020) have already died from COVID-19 in the US (confirmed, not estimated). Hundreds of thousands more may die before the pandemic is over if deaths continue as they have in the past. In contrast, the confirmed (not estimated) deaths due to flu typically range from ~3,500 – 14,600. Thus, the current number of confirmed COVID-19 deaths is at least 9.4 times higher than the annual number of confirmed flu deaths and we are only ~halfway through the year. Moreover, frontline workers are reporting that COVID-19 is not like the typical flu and they are struggling to care for the numerous severely ill patients. We are learning more about COVID-19 on a daily basis, but this is still a very new illness, with relatively little understood about its effects or possible treatments, making it very different than the typical flu.
  • Many of the people who are not killed by the virus can still get extremely sick and have long-term lung damage, neurological effects or brain damage, and may even develop diabetes or male infertility. See FAQ #2 for statistics about rates of severe illness.

2.      I’m young and healthy, so I don’t need to worry, right?

  • It is true that risks of severe illness and death are much higher for people over 60 and those with obesity, diabetes, respiratory disease, cancer, or are otherwise immunocompromised. But the illness can also be severe, and occasionally cause death in younger people at significant rates. This is especially true if they are obese. Although not enough work has been done, who gets really sick might also be related to exposure (the amount of virus that the person is infected with), where viral particles end up (deep in the lungs vs the upper respiratory tract), previous exposure to other coronaviruses (potentially conferring some “natural immunity”), and genetics (influencing both “natural immunity” and the extent to which the immune system “over-reacts” causing harm to the body). The illness tends to be worse in men, those with type A blood (likely due to a correlation with genetic factors related to the immune system), and racial minorities (in the US).
  • Even if you don’t get severely sick yourself, you could pass the virus on to someone who is in a higher-risk category. Some estimates suggest that 10-15% of those infected, in other countries, have experienced severe illness. Another estimate suggests that as much as 25% of the US work force is at high-risk for severe illness (even if they do not die). The difference in estimates may be due to differences in the greater prevalence of underlying health conditions in the US population compared to China. But by either estimate, it still amounts to the potential for a very large number of people getting severely ill (for example if 10% of the 382 million people in the US get severely ill, that would be 38 million people).

3.      But it doesn’t affect kids, right?

  • SARS-CoV-2 rarely affects children in the same way it affects adults. Kids can sometimes get severe COVID-19 (~5% of confirmed cases are severe, between 0.6 and 2% require the ICU) and deaths of those under 18 have occurred. But these are rare events (less than 0.1% of infected children die) and few children seem to show severe symptoms in the near-term. However, up to 40% may experience moderate short-term symptoms, including pneumonia. Symptoms may be worse for infants and those who are immunocompromised or have chronic lung conditions. Moreover, evidence is accumulating that months after infection by SARS-CoV-2, some children may develop a different sort of disease, called Multisystem Inflammatory Syndrome in Children (MIS-C), caused by the same virus. Luckily this disease may be easier to treat. But we don’t yet know how common MIS-C will be in children infected with SARS-CoV-2 and we don’t know if other symptoms will develop many months or years later, as is possible with Polio. Much is still unknown about this newly identified syndrome.

4.      But masks don’t really work, right?

  • Most masks will not provide perfect protection from other people who are sick, but that doesn’t mean they don’t help at all. N95 masks can be 95% effective at blocking airborne particles carrying viruses, when properly fitted and worn correctly (which is not common for the general population). Although it is not their intended purpose (see 4b), regular surgical masks, as well as cloth masks, can still block some virus particles from entering your airways, especially larger droplets (~30-70% of particles). Any reduction in virus particles entering your airways will lower your dose of virus, decreasing the chance you will get sick and also decreasing the chance of severe illness.
  • Regardless of the ability of masks to protect you from other people, all masks provide a good way to trap virus particles coming out of your own airways, reducing the chance you will infect others. Masks are especially good at trapping larger droplets and may also reduce smaller “aerosol” particles. Researchers have found that 30-60% of spread of COVID-19 likely occurs from people who are not aware they are sick (either have no symptoms or minor symptoms they may not notice). That means I could be infected and contagious right now. Or you could. Regardless of symptoms. Thus, if you want to protect other people (your grandparents, your parents, your co-workers, your friends, the employees at the grocery store), wearing a mask is a good way to do it. If almost everyone wore masks, than I would be protecting you from me, and you would be protecting me from you, and thus we would all be protected. Studies have shown that widespread mask usage could reduce transmission sufficiently that we could open things back up relatively safely, even if masks are not always worn correctly.
  • Note: unfortunately, initial public communication regarding masks suggested they should not be worn unless you were sick. This was based on the faulty assumption that only symptomatic people could transmit the virus to others and that the virus is only transmitted by large droplets from those in extremely close proximity. We now know that both of these things are not true (see studies referenced elsewhere in this FAQ) and thus the guidance on masks has changed. That has led to a lot of confusion.

5.      But as long as I stay 6 ft away, I don’t need a mask, right?

  • If the virus only traveled in large droplets, then 6 ft, without a mask, might be enough. However, there is now substantial evidence that the virus can travel much farther, in coughs and sneezes (over 20 ft) and in smaller particles, especially in enclosed air spaces. Because these small particles can accumulate in the air, over time, whenever you are sharing the same enclosed air space with another person, no matter the distance, a mask is likely a good idea. Note: for unknown reasons, not everyone infected with COVID-19 spreads the illness, but you and I can’t tell who will and will not spread the virus, so it is best to assume anyone could be a spreader, including oneself.

6.      What activities place me at the most risk for infection of SARS-Cov2? How can I reduce my risk?

  • There are multiple factors that go into determining your risk. A friend and colleague has suggested there are 4 Cs to avoid; to paraphrase, one should avoid confined air spaces, crowds, closeness, and prolonged contact time. To get sick, you must receive an infectious dose of the virus. Thus, brief exposure to a small amount of the virus is unlikely to make you sick (e.g. walking quickly past someone without a mask, outside). Every person’s willingness to accept risk is different. Most experts agree that the most risky situations are to be inside in an enclosed air space, with other people, without masks, for a prolonged period of time (>15 mins). Outside tends to be safer because of how quickly particles disperse (lowering the amount of exposure) and sunlight (which can deactivate the virus quickly). But even in those situations, it is likely best to avoid being within 6 ft of someone without a mask. If you must be inside with others who are not wearing a mask, it would be best to keep your distance, keep the time short, increase ventilation in the room if possible, and wear both a mask (ideally N95) and a face shield.

7.      I already had it and recovered, so I’m immune, right?

  • At the moment, there is still uncertainty about the duration or extent of immunity. Antibodies to the virus appear to substantially decline within 3 months for most people, but this does not mean you lose immunity when this happens. That is because an infection with SARS-CoV-2 does appear to illicit a strong immune response that may create a “memory” in certain types of immune cells, allowing them to ramp back up antibody production quickly in the event of another exposure to SARS-CoV-2. Immunity lasts for at least a year after recovery from SARS (SARS-CoV). There is hope that immunity will last at least that long for COVID-19 (SARS-CoV-2). The fact that SARS-CoV-2 mutates relatively slowly could also help increase the duration of immunity and the effectiveness of a vaccine.

8.      I was exposed, but my test came back negative, so I’m safe and don’t need to quarantine myself, right?

  • Not necessarily. First, if you were tested too soon after exposure, the virus may not yet have built up to a level where a test would come back positive. Second, most of the tests do have a chance of a false negative. The safest thing to do is to quarantine anyway if you know you’ve been exposed, but obviously individual decisions (and rules from employers) may differ. Wearing a mask and keeping your distance could reduce the chances you spread the virus to others, just in case you had a false-negative (see question 4).
    • “Variation in False-Negative Rate of Reverse Transcriptase Polymerase Chain Reaction–Based SARS-CoV-2 Tests by Time Since Exposure” published May 13th, 2020, in Annals of Internal Medicine, a peer-reviewed medical journal:

9.      But I heard that masks lower your oxygen levels and hurt your immune system.

  • Masks can be no fun to wear. They can make you feel hot and make it feel harder to breathe. But medical professionals have been wearing masks for prolonged periods for over a century without detrimental effects. Masks don’t reduce your oxygen levels or harm your immune system.

10. But children don’t spread SARS-CoV-2, right?

  • One of the many questions people have about opening schools is the likelihood that children will spread infections. Some initial, small case-studies (some of which have not yet been peer-reviewed), from locations with low levels in the community, seemed to suggest that children weren’t likely to spread it, but a new large study out of South Korea provides the best evidence to date about spread among children. This research suggests that children ages 10-19 are at least as likely as adults to spread SARS-CoV-2, while children ages 0-9 are about half as likely as adults to spread it to others. This rate of spread among young children is still substantial, and can be illustrated by a recent example from a day care in the US. Another recent study shows high levels of virus present in the upper respiratory system of children. Although the data on this topic are still somewhat limited, we now are beginning to have better evidence for understanding the frequency of spread by children.

11. But there are effective medicines or cures, right?

  • I read a study back in March, 2020 suggesting hydroxychloroquine and remdesivir were effective at reducing spread of SARS-CoV-2 in cell lines (“cells in Petri dishes”). For hydroxychloroquine the research seemed to suggest it might be effective as a prophylactic. A few subsequent studies seemingly suggested some benefits of hydroxychloroquine in humans, but these studies were often small, correlational, or had confounding factors. Results of properly controlled studies with placebos, in whole humans, suggested there was no evidence for a benefit of hydroxycholorquine as a treatment for COVID-19, including as a prophylactic (see links below). In other words, there was no statistically significant benefit that could be attributed to the medication (and not some other factor). Science is a process and many studies are needed to reach extremely strong conclusions, thus I will not discount the possibility that subsequent research involving very large populations might show some small benefit (the larger the study, the greater the likelihood of finding very small, but statistically significant effects). Moreover, subsequent research could find a benefit for particular groups of people in particular situations. But the current evidence suggests hydroxychloroquine is not a widely effective treatment.
  • Remdesivir, on the other hand, has been shown, in high-quality studies, to be somewhat effective (~30%) for reducing the length of to recovery of critically ill patients.
  • More recently, a high-quality study has shown that a cheap and widely available steroid, dexamethasone, seems to reduce the death of severely sick patients by ~30%. More research is needed, but this medicine appears to show more promise for treatment of COVID-19 than either hydroxychloroquine or remdesivir.
  • There are some promising results from early research on the use of monoclonal antibodies. These are neutralizing antibodies synthesized in the lab that may be useful both as a prophylactic or in treating very ill patients. But more research is needed before these can be approved for use widely.
  • There are a large number of additional drugs that some have suggested might be effective in treating or preventing COVID-19. Much of the current evidence for or against them is based on unpublished anecdotal stories, case studies, cell lines, or uncontrolled correlational studies. As such, the perceived effects of many of these drugs may be explainable by coincidence (the person would have recovered at that time without the medicine and the timing of recovery after receiving the medicine was a coincidence), another medicine or treatment that was administered simultaneously, the placebo effect, temporary benefits for symptoms only, a very tiny effect, or, in some cases, omission of cases that don’t fit the narrative the person is trying to tell (i.e. lies or manipulation). That said, some of these potential medicines may end up being very effective. But controlled trials (ideally placebo-controlled, double blind, randomized trials) are needed before widespread use of any medicine should be recommended. Part of the reason is unintended effects and side effects. For example, the steroid dexamethasone has been shown to be effective in reducing deaths of critically ill patients, likely by reducing inflammation associated with an over-reaction of the immune system, but this medication is not without side effects and it could make things worse if given to the wrong person at the wrong time.
  • Note: there is a regularly updated document on the NIH website that summarizes recent developments related to treatment of COVID-19:

12. Additional Resources:

  1. What it would take to reach “natural” herd immunity:
  2. Face mask reduction of transmission within households:
  3. Comparing effects of face mask wearing between US states:
  4. Comparing effects of face mask wearing between countries:
  5. A state-by-state and county-level assessment of pandemic severity and rate of spread:
  6. Another state-by-state and county-level assessment of pandemic severity and rate of spread:
  7. Psychological reasons why relying on personal decisions regarding mask wearing and other risk-taking policies probably won’t work:
  8. Coronavirus vaccine tracker:
  9. How COVID-19 affects the brain, lungs, and heart:
  10. How one ER doctor thinks about acceptable risk:
  11. How to fight “caution fatigue”:
  12. Article about the debate surrounding the degree to which COVID-19 is transmitted by aerosols: