COVID Transmissions for 9-15-2020

Sep 15, 2020

Good morning! It has been 302 days since the first documented human case of COVID-19. This newsletter has now been running continuously for two months.

Headlines today, though one of the headlines is almost an in-depth in itself. I do plan to take on that bradykinin issue soon, though.

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

Keep the newsletter growing by sharing it! I love talking about science and explaining important concepts in human health, but I rely on all of you to grow the audience for this:

Share COVID Transmissions

Now, let’s talk COVID.

Russian vaccine data called into question

Recently I shared the results of the Russian vaccine clinical trial. I have been critical of this vaccine, but did note that the data appeared to indicate no surprises.

However, there are those who looked more closely at it. A group of academics has called out several unusual features in the data, and have written an open letter that they be examined more closely: https://www.reuters.com/article/health-coronavirus-vaccine-russia/fifteen-scientists-launch-critique-of-russias-covid-19-vaccine-data-idUSL8N2G84X3

The critique hinges on the fact that multiple participants appeared to have the same antibody levels across different points in time. This defies logic, would be easy for reviewers to miss, and indicates that the data are potentially suspect. I’ll continue to follow this story if these suspicions are debunked or confirmed.

Understanding how COVID-19 spread in the US in the winter

In every emerging epidemic, there is a long period of post-hoc analysis where the origins of the epidemic are analyzed, dissected, and understood in hindsight. For most emerging disease epidemics, these are not global stories. A pandemic is often the first time that the public hears academic theories about the origins and spread of disease.

Sometimes, the results of such investigations reveal things that were long suspected. It appears that this is the case for COVID-19 as well.

Two recently-published studies, both in Science magazine, have looked at the origins of the pandemic in the US.

One explored the earliest US outbreak, in the Pacific Northwest. The authors found that most likely, the virus first entered the US between January 22nd and February 10th, originating from travel from Wuhan, China. It apparently also circulated in the US for quite some time without being detected: https://science.sciencemag.org/content/early/2020/09/09/science.abc0523

This is no tremendous surprise, but in scientific inquiry it is often worthwhile to do work that confirms suspicions that we already had. Nothing can be said to be known until evidence supports it; we now have more evidence.

The other study looked at mutations in the virus to track its movements around the world in the early days of the pandemic. You can find it here: https://science.sciencemag.org/content/early/2020/09/11/science.abc8169

The researchers looked at these mutation lineages in order to develop the following map:

Image is a map of the world, viewed from the North pole  to visualize relevant continents, labeled with different transmission events of COVID-19 across broad regions. Solid lines indicate transmission events that led to sustained outbreaks, while dotted lines indicate events that eventually died out. The earliest transmissions were from China to Washington state, though not all led to sustained transmission of the virus in that location—but at least one did. Several events in February are thought to have brought the virus to California but were contained. In late January, the virus is thought to have traveled to Europe twice. One transmission, to Munich, died out. Another, to Italy, did not. Another transmission event, to New York City, originated in Europe, and led to sustained transmission in the US. Image from Science magazine.

This is an evolutionary analysis, looking at mutations and lineages in the virus to understand how it spread around the world. In this case the virus sequence helps to trace it because it acts as a sort of unique identifier, like a fingerprint. This is not a perfect analysis. While mutations are often a good way to track lineages, it’s also possible for the two virus isolates to have the same mutations just by chance. Still, this is one of the best tracing tools that we have, and we can glean some insights from it.

First, we can determine that early on, there were effective disease control measures that were taken to contain the virus. The dotted lines indicate transmission events that were contained, likely by travel restrictions and port screenings.

However, we can also see that these measures eventually failed, and we can speculate that this was because of inadequate ability to track the movement of the virus through the population—but the study doesn’t confirm this. Regardless, it is interesting to see that multiple introduction events were required to bring the virus to both the US and Europe. Perhaps this indicates that a more proactive attempt to contain such viruses at ports of origin might have prevented global spread. Perhaps it suggests something else. The conversation will continue in the academic and policy literature.

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

Learned League

I participate in an online trivia league that I don’t usually do too well with, but that has been a daily way to stay sharp. This group, Learned League, is invitation-only and runs “seasons” of competition. It adds a little bit of routine to my day that helps to grant a sense of the days actually being different. Today is Tuesday, right?

Join the conversation, and what you say will impact what I talk about in the next issue.

Also, let me know any other thoughts you might have about the newsletter. I’d like to make sure you’re getting what you want out of this.

Viral Transmissions

Discussion about this post