Is what’s happening with the flu an example of Competitive Exclusion?

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Grasshopper
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Summary:
Both live in the same niche, both experience the same selective pressures (human immune systems, social distancing, masks), but one is dominating the niche and one is being pushed to the margins.
COVID-19 is thriving, while reported influenza infections are at record lows. As someone untrained in biology, I’m probably off the mark, but that sounds to me like an example of competitive exclusion. COVID-19 has a potentially longer incubation, it’s more contagious, people can be asymptotic and spread it, and now there are new variants that are even better at spreading. Meanwhile, it seems that influenza was simply wholly unprepared for the new level of selective pressure that has come from humans trying to fight COVID-19. Influenza is failing while COVID-19 is thriving.


Is that a reasonable conclusion?
 

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  • #2
Astronuc
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Summary:: Both live in the same niche, both experience the same selective pressures (human immune systems, social distancing, masks), but one is dominating the niche and one is being pushed to the margins.

Meanwhile, it seems that influenza was simply wholly unprepared for the new level of selective pressure that has come from humans trying to fight COVID-19. Influenza is failing while COVID-19 is thriving.
The measures such as social distancing, reduced travel (particularly air travel and international travel) minimizing time with others (particularly in enclosed spaces) and wearing medical (face) masks has cut transmission of all respiratory illness (viruses).

Now that we see more interaction and more travel, we will see increases in various respiratory illnesses including influenza, colds, and SARS-Cov-2, particularly among those who are unvaccinated. I got vaccinations for influenza last October (2020) and for SARS-Cov-2 (in March/April 2021). I will get the influenza vaccine later this year. I will still wear a face mask in public.
 
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Grasshopper
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That’s true, but it appears that these measures have been far more successful against influenza than the flu. Flu seems to have fallen off a cliff. What are the reasons for COVID doing so much better but flu not thriving at nearly the same level?

https://www.healthline.com/health-n...eared-this-year#What-drove-down-flu-activity?

“Due to influenza’s short incubation period and widespread population immunity, the measures used to stop the spread of COVID-19 also caused flu activity to drastically drop.

Between Oct. 1 and Jan. 30, only 155 people in the United StatesTrusted Source have been hospitalized with the flu.

That’s a 98 percent decrease from the same window of timeTrusted Source in the 2019-2020 flu season in which 8,633 people were hospitalized with the flu.

The precautions used to prevent COVID-19 ended up drastically reducing influenza transmission.”



Could it be said they occupy the same niche, and would this be an instance of competitive exclusion? My confusion comes from a lack of knowledge on how they compete for whatever limited resources they share, or if they even do. I can’t imagine how being infected with one will make it harder to be infected with the other, other than increased immune response. But I CAN see how one would be better than the other at breaking through social distancing measures, since COVID seems to be superior due to its longer incubation and other things.
 
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Grasshopper
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Upon speaking to someone I know with a biology degree (in addition to the response to this thread), I would say the answer is no. The two aren’t necessarily competing for the same resources. There doesn’t appear to be a reason why one would exclude the other from infecting the same host. Rather it’s about a new parasite causing a behavioral change in the host which the old parasite was not suited to. As Astronuc said earlier, when COVID-19 is under control and behavior shifts closer to what it originally was, influenza will bounce back.
 
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  • #5
atyy
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Upon speaking to someone I know with a biology degree (in addition to the response to this thread), I would say the answer is no. The two aren’t necessarily competing for the same resources. There doesn’t appear to be a reason why one would exclude the other from infecting the same host. Rather it’s about a new parasite causing a behavioral change in the host which the old parasite was not suited to. As Astronuc said earlier, when COVID-19 is under control and behavior shifts closer to what it originally was, influenza will bounce back.
Yes, they have to compete for the same niche (which is not clear in this case).

There is the related question for cold viruses, which someone pointed out in another thread (I don't remember).

https://www.bbc.com/news/health-56483445
The virus that causes the common cold can effectively boot the Covid virus out of the body's cells, say researchers.

https://academic.oup.com/jid/article/224/1/31/6179975
Human Rhinovirus Infection Blocks Severe Acute Respiratory Syndrome Coronavirus 2 Replication Within the Respiratory Epithelium: Implications for COVID-19 Epidemiology
Kieran Dee, Daniel M Goldfarb, Joanne Haney, Julien A R Amat, Vanessa Herder, Meredith Stewart, Agnieszka M Szemiel, Marc Baguelin, Pablo R Murcia
The Journal of Infectious Diseases, Volume 224, Issue 1, 1 July 2021, Pages 31–38
 
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Astronuc
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A family member who manages a family medical practice mentioned seeing the four usual respiratory illnesses (RSV/parainfluenza, adenovirus, rhinovirus and coronavirus) in addition to COVID cases. Influenza is not as prevalent, and in fact, only one case in 6 months.

Patients are becoming more belligerent to the point of pushing staff around, as well as yelling in person or over the phone for treatment/appointment/vaccination/medical records. And some don't want to wear face masks. :mad:

Two staff members (one is only 24 years old) became ill with COVID-19, and one quit the practice due to the severe illness, while the other is feeling closer to normal only 6 months later. Another staff member lost parents to COVID-19.

Hospitals have been losing money treating Covid patients and medical practices are asking doctors to accept less pay for more work. So, like many doctors, the family member is not planning to renew the contract and will retire.
 
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  • #7
DaveE
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Not competition. You could get flu and COVID-19 at the same time*. They live parallel existences in the same population.

This BioFire ID monitoring site is worth looking at if you need more geeking fuel.

* Edit: But maybe not as easily as if you get them separately. Anything that activates your immune system, like an adjuvant in a vaccine, makes you less susceptible to infection. For example, there is some evidence that getting an MMR vaccine (whether you need it or not) gives you partial, temporary, resistance to SARS-CoV-2 infection.
 
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DaveE
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This is an interesting paper about the effects of the COVID-19 based non-pharmaceutical interventions on RSV epidemiology in Australia.
 
  • #9
Grasshopper
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Not competition. You could get flu and COVID-19 at the same time*. They live parallel existences in the same population.

This BioFire ID monitoring site is worth looking at if you need more geeking fuel.

* Edit: But maybe not as easily as if you get them separately. Anything that activates your immune system, like an adjuvant in a vaccine, makes you less susceptible to infection. For example, there is some evidence that getting an MMR vaccine (whether you need it or not) gives you partial, temporary, resistance to SARS-CoV-2 infection.
This was one thing I considered, but as a non-biologist I wouldn't know how much of a factor it is. I'm assuming not a huge one.

But, I wonder if the same thing would apply to different strains of SARS-CoV-2? Clearly newer variants are more fit in terms of reproduction, but is one strain actively harming another?
 
  • #10
jim mcnamara
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No. For example consider founder effect.

Suppose you go to an isolated island, that is perfect for growing grass and there are no grasses there to compete with any grasses you may plant. But you have only one pound of seed for species A, and 20 pounds of seed for species B. You plant the seeds and come back later.

So in this contrived example what grass species will be more common after two growing seasons? --> B.

The Covid delta variant is the most common one in the unvaccinated US population. Why. One good answer is founder effect. Delta becomes infectious while still asymptomatic ~1 day faster than other variants. It also generates greater numbers of new virus particles in the patient.

Consider unvaccinated populations as being like the island above. So - delta gets wins new infections with numbers and no immunity. Founder effect.

Modeling and explanation of Covid and Founder Effect -
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7543514/

It is also an example of R selection in action: Get a foothold before competitors by using more propagules.
https://www.oxfordreference.com/view/10.1093/oi/authority.20110803100403659
 
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  • #11
DaveE
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Clearly newer variants are more fit in terms of reproduction, but is one strain actively harming another?
There aren't different stains (so far), there are different variants. I know it sounds pedantic but the point is that strains have different behavior, different features. So far, we haven't seen any of that with any of the variants.
Anyway what does "harming each other" mean mean? Do you mean population (epidemiological) effects? If so, then yes, because they are they same virus the first one to infect would normally generate an immune response in the host which will be detrimental to any other variant that is subsequently introduced to that host.
 
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jim mcnamara
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Allelopathy is the release of molecules by one organism which suppresses the growth or reproduction of other nearby organisms. ...What I think @Grasshopper may be referring to. Allelopathy has been studied in bacteria, plants, and one celled animals IIRC. Think of it as chemically induced territoriality.

Practical:
https://www.researchgate.net/public...ic_Bacteria_and_Their_Impact_on_Higher_Plants
General:
https://en.wikipedia.org/wiki/Allelopathy

Viruses do not cause infected cells to emit allelochemicals -- AFAIK.
 
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