COVID Transmissions for 10-13-2020

28 days on surfaces?

Oct 13, 2020

Good morning! It has been 331 days since the first documented human case of COVID-19.

I found an interesting paper about the survival of SARS-CoV-2 virions on various surfaces at different temperatures, so we’ll walk through that today.

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

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Now, let’s talk COVID.

US leads 18 other countries in COVID-19 deaths; death rate among highest

A study conducted at Harvard and UPenn reports that the US has the highest COVID-19 death count of any of the 19 countries examined.

This study compared the US to other Organization for Economic Cooperation and Development (OECD) countries, considering that these are US peer countries in terms of human and economic development.

They found that the US had the highest number of COVID-19 deaths, but of course the US also has the largest population among these countries as well.

However, when looked at as a rate, the US COVID-19 death rate was 60.3 per 100,000; this put the US behind only 3 other countries—the UK (62.6), Belgium (86.8), and Spain (65.0).

What’s particularly concerning, though, is that the US death rate is a product of rising mortality, while these other countries have seen a drop in mortality. The study authors also examined deaths only after May 10th, 2020, because they noticed that in early spring, US deaths were low by comparison to the other countries. If we look at deaths after this cutoff, there are 36.9 US deaths per 100,000. In Spain, this was 8.6; in Belgium, 12.4; in the UK, 16.3. This suggests a situation where the US response was either not improving as quickly as the measures taken in these other countries, or even got worse.

The authors also looked at a cutoff date of all deaths after June 7th. In the US, the rate was 27.2 per 100,000. The closest second to this over that period was Sweden, with a rate of 10.3. Famously, Sweden has not adopted a restrictive lockdown strategy while the US had not adopted any nationally uniform strategy.

For some reason, the US is currently leading the OECD for COVID-19 deaths per 100,000, when you look at the second half of 2020. This is a sad state of affairs.

Read the full paper here: https://jamanetwork.com/journals/jama/fullarticle/2771841

Survival of SARS-CoV-2 on surfaces at various temperatures

There’s a new paper out, from Virology Journal, looking at the survival of SARS-CoV-2 particles on surfaces: https://virologyj.biomedcentral.com/articles/10.1186/s12985-020-01418-7

This study is interesting in several ways. Importantly, the researchers looked at the recovery of actual, viable virus from these surfaces using a cell-based infection assay. They also conducted all incubations in the dark, to remove the influence of ultraviolet light on virus survival. Finally, they conducted their experiments at various temperatures; 20 degrees C (68F), 30C (86F), and 40C (104F).

Surprisingly, they were able to recover detectable amounts of virus from various surfaces for up to 28 days when those surfaces were kept at 20C. Surfaces tested included stainless steel, glass, cotton cloth, vinyl, and both paper- and plastic-based money (this was an Australian study; plastic-based money is used in Australia).

Recovery of viable virus declined much more quickly at the higher temperatures, though on certain surfaces at 30C virus remained viable for around 2 weeks.

In previous studies, results had indicated that most virus particles cease to be viable after about 24 to 72 hours, which is difficult to square with the results presented here. My first instinct is to be suspicious of these results because the it seems that the amount of recoverable virus is much much smaller than the amount of input virus. It is possible that the reason that these researchers were successful in recovering virus for so long is that they were very thorough in trying to recover virus from these surfaces, extracting trace residual amounts. In real-life conditions, the way that people interact with surfaces is not designed to thoroughly extract small amounts of virus particles.

That said, I also think that the effort to avoid UV exposure mattered substantially here, and I’m disappointed in the authors for their failure to adequately compare between lighted vs dark incubation conditions. They could presumably have doubled their experiments with one in light and one in dark for each type of surface. This would have been—forgive me—enlightening.

I don’t think we should all panic as a result of this publication. 72 hours is probably more than enough time to wait for something to be considered safe; surfaces are not currently thought to be a big driver of transmission and epidemiologists have not traced a lot of cases back to surfaces. Airborne transmission appears to be the biggest threat for spread of SARS-CoV-2.

However, we may have learned something here about the effects of exposure to light on SARS-CoV-2 particles, and that’s pretty interesting. We’ll have to keep an eye on where this goes.

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

Keeping up with friends

When I got sick a couple of weeks ago, I sort of fell off the map when it came to being in touch with people. Now that I’m feeling better I’m trying to reach out more and see how everyone is doing. Feel free to reach out!

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