COVID Transmissions for 10-13-2020

Another reinfection

Oct 14, 2020

Good morning! It has been 332 days since the first documented human case of COVID-19.

In the Talk Back section, some discussion of how to control for variations in public health data. In addition to that, headlines about reinfection and passage of COVID-19 from parent to newborn.

As usual, bolded terms are linked to the running newsletter glossary.

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Now, let’s talk COVID.

Another case of symptomatic reinfection

Another report of a symptomatic reinfection has been published in Lancet Infectious Diseases today, covering a patient who had a documented resolved COVID-19 infection followed by a reinfection, with more severe symptoms, substantially later: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30764-7/fulltext

At this point there is still nothing alarming about this. There appears to only be a small proportion of patients who are susceptible to this type of reinfection, with fewer than 10 such cases documented out of 20 million+ cases globally. Still, it is worth keeping an eye on these situations.

Something worth noting, though, is that we are more likely to detect these types of reinfections—because they cause noticeable symptoms—than we are to detect reinfections where the immune system does its job and there is no disease or transmission. So, it’s very possible that many more of that type of reinfection is occurring in the world, and we are just not detecting it, making these isolated cases look more concerning by comparison.

No great risk to newborns from COVID-19 infections in their mothers

A paper in JAMA Pediatrics looks at the odds of COVID-19 in infants born to mothers with COVID-19 during delivery. This study looked at 101 people with COVID-19 who had babies in 2 affiliated New York City hospitals and found that only 2% of the infants had positive tests for COVID-19, and none of those with follow-up (n=55) had symptoms.

This isn’t exactly a huge study, but the relative rarity of even positivity in the infants is reassuring.

I will note that the hospitals used an extensive protocol to try to prevent transmission from mother to child, including masks, which is described in full in the paper. Without these measures we might have seen a greater rate of transmission.

Read the paper here: https://jamanetwork.com/journals/jamapediatrics/fullarticle/2771636

What am I doing to cope with the pandemic? This:

Cooking with unusual rice

The pandemic has introduced me to “Jade Pearl Rice,” which I’m pretty sure is a totally modern innovation that is made to seem ancient and mysterious through the power of Branding.

It’s an organic rice that is infused with bamboo extract, which gives it a slightly greenish color and also a kind of woody flavor that’s quite nice. Lately, I’ve been trying to find new and different ways to use it.

So far, I like it with fresh bitter greens that have been lightly sautéed, since that complements the bamboo extract flavor quite well in my opinion. However I also find it’s quite good as a bed for a couple of fried eggs with breakfast, too.

In response to yesterday’s headline item about the study looking at death rates in OECD countries around the globe, reader Robert Berger asked the following:

Does the study on mortality rates in different countries take into account the different methods of tracking and defining "Covid death" in each country, and in each state in the US?

Here’s my response:

Great question! For those not as familiar with this, it is not always clear what someone has died of when they die. Imagine, for example, a COVID-recovered patient who dies two weeks after leaving the hospital from a cardiac event. Are they a COVID death? This all depends on the way that data are classified in the country and locality where they died, and also the evidence that COVID-19 was responsible for their death. It’s actually rather complicated to decide what someone died of.
The researchers in this study used statistical methods that attempt to get around this kind of kind of variation. Specifically, the estimates of mortality were conduced using a regression analysis based on something called a fixed-effects model. I am not an expert in statistics, but my understanding of fixed-effects models is that they are used under conditions when it is expected that certain data might be in error for reasons that are uniform across the dataset; ie, where it is unlikely that variations in the data occur at random, but instead occur due to some fixed effect.
The application of national and locality medical criteria to adjudicating deaths potentially due to COVID-19 could be seen as a fixed effect. There would be some sort of random variation between different individual medical practitioners ruling on cause of death, but at the national level one might expect that discrepancies between countries would be nonrandom and would occur due to differences in these rules.
I am not sure that this fully accounts for differences between countries in terms of adjudicating deaths; it is just my interpretation of what is written in the methods section of the paper. If any readers see a serious error in what I’ve written here, please let me know.
That said, I would summarize all questions about modeling and estimation of this type by noting that no model is ever perfect. The question is whether the imperfections made the model lose usefulness. I don’t believe that in this case they did. I think that OECD countries have relatively similar methods of adjudicating deaths, and even with minor variations I wouldn’t expect such disparities as ended up appearing between the US and other countries in the analysis we talked about.

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