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Saturday, March 14, 2020

A quick Q&A on coronavirus

A noted Christian journalist whom I respect recently offered his answers to various people's questions about the coronavirus. I'm afraid I didn't think his answers were correct. So I'll quote his answers, then give my answers.

COVID-19 (short for novel coronavirus 2019) is a strain of coronavirus

Technically, SARS-CoV-2 is a strain of coronavirus, while COVID-19 is the disease it causes. It's like HIV/AIDS where HIV is the virus, while AIDS is the disease.

COVID-19 appears to be able to be transmitted through the air, while influenza virus cannot.

1. On the contrary, COVID-19 and influenza are transmitted "through the air" in that the most common mode of transmission for both is via direct droplet spread. Droplets from coughing and sneezing which hang in the air.

2. Both viruses (virii?) are also transmitted via fomites, i.e., inanimate objects like door handles and table surfaces.

This is why COVID-19 is able to spread more rapidly than influenza.

The primary reason COVID-19 is able to spread rapidly is not because of its mode of transmission, but because it's a novel virus to which humans have no innate immunity.

The key reason this virus is potentially more dangerous than the flu is because we have no protection against it.

1. I don't think comparing COVID-19 to the seasonal flu is comparing like to like. I think it'd be more accurate to compare COVID-19 to (say) the Spanish flu rather than the seasonal flu. I'll try to explain why in response to your next statement.

2. In any case, I wouldn't necessarily say a coronavirus such as COVID-19 is more dangerous than influenza. Influenza is no joke. Many infectious disease experts have long argued that influenza is the most threatening virus to humanity. That it has the most potential to cause a pandemic.

And indeed it has. I mean influenza might seem routine to people, but the truth is influenza has caused many of the most severe epidemics and pandemics in human history. Influenza has caused severe epidemics and pandemics in 1743, 1889, 1918 (the Spanish flu), 1957 (the Asian flu), 1968 (the Hong Kong flu), 1977 (the Russian flu), and 2009 (the Swine flu).

In general, influenza pandemics have had high mortality rates.

3. Of course, in recent years, coronaviruses have likewise been quite severe. SARS in 2003 and MERS in 2012 were very bad. Both SARS and MERS are coronaviruses.

For all of us alive today, strains of the flu have existed our entire life. Almost everyone gets the flu at some stage of life and are therefore able to build up immunity. We also have vaccines created each year that protect people from new stains. Despite these immunities, we still have 291,000 to 646,000 deaths worldwide from the flu each year.

1. That's a bit misleading. Influenza is dangerous because influenza has very high mutation rates and frequent genetic reassortments. That is, influenza can mutate on its own (antigenic drift), but it can also mutate when two different influenza viruses infect a human or an animal (e.g. pig) at the same time, they swap and rearrange genetic material, and create a new hybrid virus (antigenic shift).

Influenza's antigenic drift is often enough to fluster our immune systems, hence the need for annual flu shots aka flu vaccines. However, its antigenic shift can wreak havoc on our immune systems. That's how all the aforementioned influenza pandemics started.

2. Also, as you say, there are hundreds of thousands dying each year from the seasonal flu, which implies our immune systems can't always handle even relatively minor antigenic drift in influenza, let alone major antigenic shift in influenza.

Add to that the fact that this virus is about 7-10 times more lethal than the average strain of influenza. That's COVID-19.

1. We don't know for a "fact" that COVID-19 is "7-10 times more lethal" than the seasonal flu. Sure, it might end up to be 7-10x more lethal, but we don't know that right now, inasmuch as we're still in the midst of a pandemic, so the case fatality rate is dynamic. And the case fatality rate likewise depends in part on how many people we test, and as we know the US has only tested a fraction of its population.

2. By the way, if Johns Hopkins is correct, then the case fatality rate for the coronavirus will be 0.6% at worst. It could even be lower. If it's 0.6%, while the seasonal flu is around 0.1%, then COVID-19 would be 6x times more lethal than the seasonal flu (if not less). Of course, I realize this is debatable, but Johns Hopkins as a medical institution is well-respected, so at the very least their figure shouldn't be dismissed out of hand. Likewise South Korea's case fatality rate seems to be around 0.6%. And South Korea has done extensive testing (unlike us), which makes it more likely to be reliable.

3 comments:

  1. Hawk, do you have an opinion on church closings? I've seen a lot of statements on it but I haven't seen a lot of analysis of the wisdom and ethics of it relevant to the severity of the situation from knowledgeable people. The closest I've seen is this Facebook thread that Jeff Durbin recently shared:

    https://m.facebook.com/story.php?story_fbid=10106661382183671&id=17026312

    But not being an expert I'm not if this accurately weighs the potential dangers involved. You seem to have some expertise in this area so I thought I'd see what you think.

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    1. Thanks, WittenbergsDoor! That's a good question. I have to admit, though, I have no expertise as far as whether we should close churches. That's because I'm not a pastor or theologian or ethicist, and I'm not an infectious disease specialist, epidemiolgist, or public health expert. That said, if you don't mind listening to my thoughts, then I think I'd say the following:

      1. I agree with the main thrust of what the FB post that Jeff Durbin shared is saying. I don't think his analogies work (e.g. I don't think a pandemic is comparable to driving cars), but I think I get his point. At the very least he's asking a few good questions.

      2. I'm afraid I'll have to sidestep the question about closing churches, at least for now, since it'd involve writing a lot more. However, I'll give some information that could inform the question of whether we should close churches. Of course, what I'll offer is only one perspective (i.e. epidemiological/medical), but there are more fundamental perspectives to consider (i.e. theological, ethical). And (pace Benjamin Franklin) there could be choices to be made between security and liberty (first amendment), but I'd personally err on the side of liberty even if it came to that, i.e., I think Christians should be free to meet and worship in churches. And I think that could be argued biblically/theologically as well as legally/Constitutionally, but again I won't make a case here. I'll just talk about the coronavirus instead.

      3. There are two factors at play which I'll call the transmission rate and the fatality rate. I realize I'm simplifying, but if you're interested in details a book like The Rules of Contagion would be good to take a look at.

      a. Transmission rate. There's a simple scene in the movie Contagion where Kate Winslet's character a good job explaining this. Worth watching. Anyway, the way the experts (e.g. epidemiologists) measure how "contagious" a disease is is with something called the R0. If the R0 of a disease is 10, then that means for every 1 person that's infected, they will infect 10 other people on average. If the R0 is 2, then for every 1 person infected, they will infect 2 other people on average. An R0 of less than 1 is ideal because that means for every 1 person infected, they'll infect less than 1 person. So the disease can't "reproduce" itself. For example, the measles is highly contagious. It has an R0 over 10. Maybe 12 or 13. I forget exactly, but it's very high. So every 1 person who has the measles will transmit it to 10+ people. If I recall, the seasonal flu has an R0 around 1.5, give or take (depends on the particular flu season).

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    2. b. Fatality rate. At the same time, if someone is infected with a disease, then how likely are they to die from it? Experts call this the case fatality rate (CFR). So there are some infectious diseases where the CFR is near 100%. If you get it, you'll almost surely die from it (e.g. kuru, Creutzfeldt–Jakob disease - which, by the way, is why I believe this story is truly miraculous). Rabies is also nearly 100% if untreated. Ebola is around 80%, if I recall, again if untreated. Smallpox before we developed a vaccine was like 60%. The black death or bubonic plague (pneumonic) would be around 50% if untreated. MERS (another coronavirus) in 2012 was around 30%. SARS (another coronavirus) in 2003 was approximately 10%. The Spanish flu (an influenza virus) in 1918 which killed between 50-100 million worldwide was around 3%-5%. The seasonal flu (i.e. influenza) is less than 1%. In fact, the seasonal flu is around 0.1% (one-tenth of a percent).

      4. Now the question is, what's the R0 and CFR for this current coronavirus (i.e. SARS-CoV-2/COVID-19)? The answer is no one truly knows. Not until the pandemic is over or almost over. That's because the R0 and CFR depend on the data we have and the data is still coming in. People are still getting sick and dying. Of course, experts like epidemiologists can make reasonable estimates and projections about it. But the responsible experts will emphasize that the R0 and CFR are not set in stone, not yet.

      5. So what are best estimates for the R0 and CFR? Right now, the R0 estimates I've seen are between 2-3, while the CFR estimates are between 0.6%-4% (sometimes even less than 0.6%, but sometimes even more than 4%).

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