More on coronavirus: ask the doctor!

My primary care physician, Dr. Alex Lickerman, has written the sixth part of his series on coronavirus and the pandemic, which you can access by clicking on the screenshot below. It also links to the previous five pieces. And, as with part 5, Alex has kindly offered to answer readers’ questions in the comments. Ask him anything (about the virus and pandemic, that is)! He might not have time to respond to everyone, but he’s told me he will have some discussion with the readers here.

Be aware that when Alex refers to SARS-CoV-2, that is the virus that causes the disease COVID-19.

Do read the piece, though, before posing any questions. The topics covered include the following:

  • Why do we have to do those onerous double-blind tests of antiviral drugs? Why can’t we just give them to people if they look propitious?
  • What’s the value of antibody testing to see who’s had the virus? Should you get an antibody test?
  • What’s the best way to estimate the prevalence of Covid-19? This tells you your likelihood of getting the virus.
  • If you’ve had Covid-19-like symptoms, what’s the probability that you’ve had the virus?
  • When should we start mass testing for antibodies to the virus?

As Alex says, the post has a lot of math and statistics, but if you want the bottom line, well, skip to the “bottom line” part of each section, and to the “Conclusion” at the end of the post.

Then put your questions in the comments. Alex will be looking at them from time to time. Again, don’t be shy. You can ask about anything related to the pandemic or the virus, not just about what’s in the post.


  1. Liz
    Posted April 17, 2020 at 12:17 pm | Permalink

    If you get COVID-19 and recover, will you have immunity and for how long?

    • Posted April 17, 2020 at 1:12 pm | Permalink

      Answered in the article. Bottom line is we don’t know. Seasonal coronavirus (related to SARS-CoV-2) immunity seems to wane in children after a few months. We’ll have to wait until we have widespread, accurate antibody testing to observe reinfection rates in those with antibodies.

  2. amyt
    Posted April 17, 2020 at 12:28 pm | Permalink

    Saw a graphic from a study which I now can’t find the original reference. It showed dispersal of breathes/droplets depending on activity. The graphic showed
    15 feet when walking
    33 feet for slow jogging
    65 feet! for running or biking
    So shouldn’t these folks be wearing masks and increase their distancing? Thoughts?

    • Posted April 17, 2020 at 1:13 pm | Permalink

      Probably, yes. But keep in mind the extremely low prevalence of asymptomatic infection in the general population at present (<1%). And though virus particles may indeed spread out as far as you describe, we still don't know what concentration is needed to be infectious. But given that wearing a mask has little downside, I'd suggest it.

  3. GBJames
    Posted April 17, 2020 at 12:32 pm | Permalink


    • Mark R.
      Posted April 17, 2020 at 4:41 pm | Permalink


  4. Posted April 17, 2020 at 12:32 pm | Permalink

    “the investigators detected seasonal coronavirus RNA in respiratory droplets and aerosols in 30 percent and 40 percent of samples, respectively.”

    But a bystander’s chance of getting infected depends on viral load, right? And droplets presumably carry far more viral load than aerosols. Can we get an order-of-magnitude estimate for the relative risks for these two methods of transmission? One reason I’m asking is that droplets hang around for less time.

    • Posted April 17, 2020 at 1:05 pm | Permalink

      Sorry, I had only read the one post (“part 6”), but now that I’ve read part 5, I guess the answer is: we don’t know. Don’t know how viral load relates to probability of infection, in particular.

  5. Charles A Sawicki
    Posted April 17, 2020 at 1:02 pm | Permalink

    Hi Dr. Lickerman, thanks for taking questions.
    I’ve noticed that the ratio of total deaths to total infection keeps increasing. Today the number is 0.05 for the US and 0.07 for the world. These ratios have increased significantly in the last 10 days (doubling in the US). The US stared out at about 0.01. This sort of increase is expected initially since deaths lag cases, but this is lasting too long.
    If testing is expanding, I would expect detection of a larger number of less serious cases which should decrease the ratio. If the infection was spreading very rapidly an initial decrease might also be expected.
    So a couple of questions:
    1) Is testing actually becoming more restrictive so that sicker people are being tested?
    2) This virus has shown quite a bit of mutation, so are more lethal strains developing?
    3) Some other reason?

    • Posted April 17, 2020 at 1:20 pm | Permalink

      1. Testing isn’t becoming more restrictive that I’m aware of, but does remain pretty restricted. You still can’t get tested just for having symptoms in many places. You have to be short of breath and admitted to the hospital her in Chicago at present, so we’re still under-counting both symptomatic and asymptomatic cases. (This is now starting to change, though.) I’ve seen death rates all over the place depending on location and haven’t tracked the increase you describe. If it’s real, one possibility is we’re still restrictively testing the most ill, keeping the denominator of IFR artificially low.

      2. The virus has been mutating but it doesn’t seem to be yielding much clinical significance. Virology isn’t my area, but my understanding is that coronaviruses, in general, aren’t rapid mutators that produce rapidly increasing virulence or mortality, but maybe someone with more experience there can weigh in.

      • Charles A Sawicki
        Posted April 17, 2020 at 1:41 pm | Permalink

        I have been using numbers from Johns Hopkins, which seem to be best. This increase has been monotonic if you average over 4 days. Ten days ago the ratio for the US was about half what it is now.
        This seems like a pretty bad sign if it’s due to testing is becoming more restrictive.

  6. normwalsh
    Posted April 17, 2020 at 1:22 pm | Permalink

    Dr. I am wondering what percentage of victims recover from a respirator session and those who do not.

    • Posted April 17, 2020 at 1:53 pm | Permalink

      Those stats are all over the place, but the best answer was published in an English study that showed a 48% mortality rate if you’re sick enough to need mechanical ventilation.

  7. rickflick
    Posted April 17, 2020 at 1:50 pm | Permalink

    If I wear a mask to the hardware store, am I only protecting others from the chance I’m positive (but asymptomatic), or do I gain at least some small protection for myself?

    • Posted April 17, 2020 at 1:54 pm | Permalink

      You gain very little benefit yourself. You’re really wearing the mask to protect others from you.

  8. Ken Kukec
    Posted April 17, 2020 at 2:12 pm | Permalink

    Ask him anything (about the virus and pandemic, that is)!

    Good thing you put in that proviso. No telling what some of the sick puppies round here (by which I mean me) might’ve otherwise asked the poor, unsuspecting sawbones. 🙂

  9. Posted April 17, 2020 at 2:32 pm | Permalink

    Reblogged this on The Logical Place.

  10. David Eberth
    Posted April 17, 2020 at 3:14 pm | Permalink

    While I totally agree with the conclusion that the infection is far more widespread in the general population than the testing numbers indicate, the attempt here to estimate that rate still has too many assumptions. Meritorious in its goals, but largely worthless as a quotable number. Hard data are so far only available from places like Iceland, which is doing large amounts of asymptomatic testing, cruise ships, the recently published (NEJM) New York hospital obstetrics study, and the recently released info on the USS TR, all of which confirm high rates of asymptomatic infections, but no reliable values yet (lots of confounding factors). Regardless, one further conclusion seems certain, if infection is more widespread then mortality rates in broad general populations will general be lower than originally predicted. I look forward to more hard data.

  11. Ken Kukec
    Posted April 17, 2020 at 3:31 pm | Permalink

    I recently read that one of eight pregnant women being admitted for childbirth at hospitals in New York City (the hotspot di tutti hotspots in the US) are testing positive for COVID-19 even though they have experienced no symptoms. Does this suggest that incidence of asymptomatic infection (at least in the NYC-area population) might be 12.5%?

  12. Posted April 17, 2020 at 4:03 pm | Permalink

    Thanks for taking questions. I’ve noticed that the stats usually show Confirmed, Deaths and Recovered. It certainly looks like the Recovered numbers are not updated very well. Current Illinois stats are 27,575 confirmed, 1,134 deaths, and 2 Recovered.

    I presume more than two people have recovered. One reason I’ve heard these stats are lacking is that when I get better, I don’t tell my health care provider and so they don’t know.

    Are there plans to try to get a better handle on outcomes at some point, including the recovered stat? Is there existing communication available to the CDC, etc. on this measure? Is it even important?

    • Posted April 17, 2020 at 4:43 pm | Permalink

      Great questions, all. I don’t know the answers. Once we have good quality antibody testing, we should be able to get a handle on the number of folks who’ve recovered. Though I don’t know if that will be tracked by the CDC.

  13. Mark R.
    Posted April 17, 2020 at 4:54 pm | Permalink

    I have a friend who caught the virus bad, and recovered, but now he says he has the “Scarlet C”; his girlfriend is afraid to see him, and a bike rider friend refused to go on a bike ride with him. Are the people in his life overly paranoid, or are they smart to stay away? He’s in a different state than me, but since I have asthma, I don’t know if I would go on a bike ride with him either.

    • Mark R.
      Posted April 17, 2020 at 4:57 pm | Permalink

      Oh, and I wanted to add how great it is that you’re answering readers’ questions. I offer you a huge THANK YOU!!!

      • Posted April 17, 2020 at 5:06 pm | Permalink

        People who get over COVID-19 who were never sick enough to be hospitalized are almost certainly safe to be around either: 1) 14 days after they first got sick or 2) after 3 days of being fever and symptom free, which comes later. Patients who’ve been sick enough to be hospitalized have had persistent RNA in their sputum for up to 38 days (mean of 20 days), but that doesn’t mean they have persistent infectious virus as well. And it’s my pleasure.

  14. Roo
    Posted April 17, 2020 at 8:42 pm | Permalink

    My cousin had a confirmed case of Covid-19 and after getting through the more severe phase, says that she still experiences setbacks and seeming remissions. In trying to connect with other people who have recovered she’s heard other people say the same thing, and I believe one study in South Korea showed that some patients thought to be recovered tested positive again after a time.

    Is it possible that Covid-19 could be a chronic condition that is never really cleared from the body completely, at least in some people, similar to the way Lyme disease can be chronic (although I know Lyme disease is bacterial)? Or is it more likely that recovery time is just very long? Is there any way to make an educated guess based on which types of viruses tend to be chronic and which do not?

    • Posted April 18, 2020 at 7:01 am | Permalink

      Yes, a number of my patients have described a waxing and waning course of symptoms where it looks like they’ve recovered and then their symptoms recur, albeit in a milder form. I doubt this will become a chronic illness. I think it much more likely some people just take longer to recover. But time will tell.

  15. Roo
    Posted April 17, 2020 at 8:44 pm | Permalink

    Apologies, regressions, not remissions.

  16. rickflick
    Posted April 17, 2020 at 9:08 pm | Permalink

    Dr. Lickerman, I’ve heard that there is significant permanent damage to lungs and other organs due to an encounter with the coronavirus. Any truth to that that you know of?

    • Posted April 18, 2020 at 7:02 am | Permalink

      I’ve heard anecdotal reports of this, but nothing definitive. The vast majority of people are recovering completely.

      • rickflick
        Posted April 18, 2020 at 9:20 am | Permalink

        That’s good news.

  17. Ken Kukec
    Posted April 17, 2020 at 9:15 pm | Permalink

    Only patients who have previously tested positive for coronavirus are included among those whose death it attributed to the disease. So-called hotspots around the nation are also reporting large increases in people found dead at home (although no coronavirus tests are performed on these corpses, so their deaths are not attributed to the virus.) Do you have an estimate for what the actual death toll for COVID-19 might be?

    • Posted April 18, 2020 at 7:03 am | Permalink

      I don’t. Clearly some people dying from COVID-19 aren’t being counted in the death toll, but I suspect that’s a minority of cases.

  18. jedijan
    Posted April 17, 2020 at 9:34 pm | Permalink

    Hi. Hsve you heard the report about the virus not surviving on copper for more than 2 hours?

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