COVID Transmissions for 1-13-2021
COVID-19 of the future
Good morning and welcome to COVID Transmissions.
It has been 423 days since the first documented human case of COVID-19.
Today, we are going to look into the future. Will immunity to SARS-CoV-2 remain as the virus evolves? Will the disease stay as severe? Read the headlines section to explore some educated speculation on these questions.
Also, a reader comment.
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:
Now, let’s talk COVID.
Can SARS-CoV-2 evolve to escape immunity?
We’ve been talking a lot about variants and evolution of SARS-CoV-2, and something that I’ve tried to always headline is whether any variant appears to escape immunity that might be induced by other variants or by vaccines.
We are all used to the idea that the influenza virus changes every year; we know there is a new flu shot each year, and that we should all get it. Of course, very few people actually do, and for this reason, people continue to die of flu. I recommend thinking about that next time you consider not getting a flu vaccine, by the way. Everyone who dies of the flu got it because someone else chose not to get vaccinated.
Anyway, the reason that a new vaccine is needed each year is that influenza viruses can evolve to escape immunity. Their surface proteins interact with the immune system through surfaces that the virus can freely mutate without impacting function.
This isn’t the case for all viruses, though. Measles virus, for instance, does not mutate substantially enough to escape vaccines. This is probably because it cannot; the immune system may react to a part of the measles virus that is so mission-critical that any change would severely hamper the virus’s ability to survive.
So, what about SARS-CoV-2? Does our immune system react to part of it that can freely mutate, or does it react to something mission-critical that cannot change? Or, perhaps, it is somewhere in between, and it can change slowly over time as long as the right changes emerge. The answer is, we don’t know. However, a recent preprint looks at something that might give us an answer—human coronaviruses.
It seems that there has not been extensive investigation into how much human coronaviruses change year to year, probably because they do not pose a tremendous threat to human health. The researchers in this work decided to change that. They looked at a historical library of blood serum, containing antibodies against coronaviruses of years past, and explored its ability to interact with various human coronavirus sequences. As it turns out, they found that over time the earlier immune responses lose their ability to react to “future” viruses—in other words, the virus does evolve to escape immunity.
However, this change appears to be rather gradual. Immune recognition was lost only for viruses that came from 8-17 years after samples were collected. Therefore, it probably isn’t a big deal because we are often re-exposed to new coronaviruses and this alters our immune profile enough to keep us relatively current. At worst, these viruses cause a common cold.
If, somehow, you were isolated for a decade, though, you might find that the first cold that you got on reentering human society would be a bit more severe than a typical one. I don’t think it would be COVID-19 level, but, it might be pretty bad for a cold.
With regard to SARS-CoV-2, this is encouraging because it suggests that the vaccines we have developed could be stably protective for about a decade. Even if protection wanes a bit over time because of changes to the virus, we might have our immunity “updated” by circulating SARS-CoV-2 strains without experiencing severe disease. And, knowing that this can happen, we always have the opportunity to update the various vaccines.
You can read the preprint here: https://www.biorxiv.org/content/10.1101/2020.12.17.423313v1
What will become of COVID-19 once everyone is vaccinated?
Something that I’ve thought a lot about since the start of this pandemic is how, really, the emergence of a coronavirus into the human population is quite precedented. We have several human coronaviruses that circulate in human populations, and they all came into human populations from animals at one point or another in our history. It is likely that at those times, each of these viruses caused pandemics. They just happened at a time where death from respiratory illness was so much more common that they likely went unnoticed. In the time since, we have adjusted to them and they have adjusted to us. We now know them as several of many viruses that cause the common cold.
A piece in The New York Times envisions how this might happen for SARS-CoV-2, turning COVID-19 from the globe-spanning deadly disease that we know right now into something more like the type of cold that makes you stay home for a couple of days: https://www.nytimes.com/2021/01/12/health/coronavirus-immunity-future.html
Hint: the secret is widespread immunity. Vaccines can get us there.
What am I doing to cope with the pandemic? This:
Will it blend? Fake curry edition.
I really don’t use my blender enough. I’m not used to cooking with a blender, and it just doesn’t enter my mind.
Tonight I wanted to make something a little hearty given that it’s turned a bit cold, and I thought a curry would be nice, but they take an awfully long time if you don’t have a pressure cooker. Then I realized: I own a blender, and you can totally fake a simmered-for-hours curry if you have a blender.
One thing that people forget to do when trying to develop highly-spiced foods is that you really can’t add the spices last. Spices need to cook. They can’t be served raw. So, I sautéed onions, garlic, and spices together at high temperature, and then added a can of diced tomatoes until everything was nice and aromatic. I deglazed the pan with a little apple cider vinegar, then did a coarse blend on all the ingredients. Then, I added this back to the pan and added 2 haddock filets, covered the pan, and let that simmer until the haddock was cooked. It worked out nicely and didn’t take long to make at all.
To go with it, I made some rice with cumin seeds mixed in for a little added flavor.
Robert Berger left the following comment on yesterday’s edition:
The federal government has been holding in reserve vaccine doses to be used by those that received their first inoculation for their second shot. This is to insure against possible supply issues that would interfere with distribution of the second dose in a timely fashion. What do you think of the incoming administration's announcement that it will release that vaccine inventory to be used for initial inoculations?
Robert, you’ve touched on something that has been on my mind a lot lately. Here are my thoughts:
Thank you for this question, Robert! I have rather mixed feelings about this. I think it is important for the vaccine doses to be given as intended, on schedule. We do not have any evidence that they can or should be delayed. I believe there is good reason to think a delay could compromise the vaccine's efficacy.
This new plan to release all doses immediately assumes that we will have new doses manufactured by the time the vaccinated patients come due for their booster shot. I do not think that we currently possess the manufacturing capacity to fulfill this, but perhaps we will ramp up to such capacity in enough time. Perhaps we are close to it already and I am simply unaware.
Still, I am concerned that some patients will be left behind on getting their second doses according to this strategy. Yes, more patients will be vaccinated, but this means we have more patients who will need a second dose, too. I am concerned that we are doing something that's a little like borrowing from Peter to pay Paul--we are borrowing second doses from the future, to use as second doses today, in hopes we will have as many doses to distribute in a few weeks again.
It concerns me. I hope it works out for the best.
You might have some questions or comments! Send them in. As several folks have figured out, you can also email me if you have a comment that you don’t want to share with the whole group.
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.
Part of science is identifying and correcting errors. If you find a mistake, please tell me about it.
Though I can’t correct the emailed version after it has been sent, I do update the online post of the newsletter every time a mistake is brought to my attention.
No corrections since last issue.
See you all next time.
Always,
JS