Thread by @1goodtern

Right.
This is going to be an extremely long thread, because the number of ways that Covid can make you more vulnerable to other infections is *loooong*.

But here's Ten Ways That Covid Infection Can Open The Door To Other Infections Today:

(Ha. I know this is going to be one of those threads that I put loads of effort into and gets shared half a dozen times)

(and before we get properly going, not every Covid infection causes all these effects - but *some* do. The sixty four billion dollar questions are *what proportion* and *what are the effects of repeat infections* and *for how long*)

(and also, Covid isn't the only virus or infection that can cause each of these effects - it's just that not many people get repeatedly infected by all the other ones, or the effect isn't so strong. There's something *very* interesting that I'll include about that at the end... )

(and any single Covid infection might not do all of these things, either... but even that is part of the point of this thread. Even if a Covid infection does just *one* of these, then you're more vulnerable than before the infection. **Just One**.)

1 Immune System Burnout

Fighting off infections can be *hard*.
Covid infection can push the immune system into first overdrive and then immune fatigue, depleting critical immune cells (T-cells and B-cells) and leading to immune exhaustion.

2 Damaged Physical Barriers

That soreness in your throat and irritation in your lungs?
Covid damages the lining of the respiratory tract, eroding one of the body’s primary defences and making it easier for bacteria, viruses, and other pathogens to invade.

3 Excessive Inflammation

Covid can trigger an intense inflammatory response, known as a cytokine storm, that can damage tissues and create favourable conditions for other pathogens to exploit *throughout the whole body*.

(Cytokines are basically... signalling proteins released by immune cells to coordinate and amplify responses, directing cells to fight infections and inflammation. Feel free to do a search for a deeper explanation.)

4 Lymphocytopenia (Low Lymphocyte Count)

Covid often reduces lymphocyte levels, especially T-cells, which are critical for adaptive immunity. With fewer lymphocytes, the body struggles to mount a strong response to new infections.

(Lymphocytes are basically... immune cells that recognize specific pathogens, attack infected cells, and remember past infections to provide long-term immunity. There is more complexity to them than that, but I'm going to try to stay on the main topic...)

5 Dysregulated Macrophage Response

Covid can interfere with macrophage function, leading to both *overactive responses* that cause tissue damage and an *impaired ability* to clear pathogens effectively.

(In a nutshell... macrophages are immune cells that "eat" pathogens and dead cells, helping to clean up infections and trigger further immune responses.)

6 Reduced Antibody (Immunoglobulin) Production

Covid can reduce immunoglobulin production, weakening the body’s ability to neutralize pathogens, especially on mucosal surfaces in the respiratory and digestive tracts.

(Immunoglobulins (antibodies) are proteins produced by B-cells that specifically bind to pathogens, marking them for destruction and helping the body recognise them in future infections.)

(and your mucosal surfaces are the moist surfaces inside you where you meets not you, if that makes sense)

7 Bone Marrow Suppression

While Covid doesn’t seem to often directly infect bone marrow, the intense inflammation it triggers can indirectly suppress bone marrow activity, reducing the body’s ability to produce new immune cells.

8 Nutrient Depletion

Covid often depletes vital nutrients needed for immune function, leaving the body in a weakened state that makes it harder to fend off subsequent infections.

9 Nerve Damage Impacting Immunity

Covid can lead to nerve damage that affects respiratory muscles, the cough reflex, and even gastrointestinal function, all of which play key roles in immune defence.

10 Mucociliary Escalator Damage

Covid infection can damage the tiny hairs (cilia) in the lining of the respiratory tract (mucosa), reducing mucus clearance and allowing pathogens to linger and infect the lungs more easily.

11 Vascular Damage and Microclots

Covid attacks blood vessels, and cane cause microclots that reduce oxygen delivery, limit immune cell transport, and increase susceptibility to infections in tissues and organs.

12 Higher Susceptibility to Organ Infections

The combination of microclots, inflammation, tissue damage, and immune depletion in specific organs (like lungs and kidneys) leaves these tissues vulnerable to infection.

13 Misfired Immune Responses

Covid can trigger autoimmune-like responses, where immune cells mistakenly attack healthy tissues, weakening the overall immune system.

('autoimmunity' is one of the really important words when studying the after effects of Covid. Anything that tricks your body into attacking itself... you just don't want it.)

14 Decreased Vaccine Effectiveness

Covid can reduce antibody levels, potentially lowering the body’s ability to respond to vaccines, which increases susceptibility to reinfection or new infections.

At about this stage of a thread, twitter makes it look like the thread is ending, and you need to look out for a little thing at the bottom like this to 'show replies'.

There's going to be 26 ways that Covid infection can make you more vulnerable to other infections (that I've put together so far) and I've got some more thoughts at the end that are probably the most important part of the thread, so don't leave before the show's over.

15 Chronic Fatigue and Reduced Mobility

Covid leaves many people physically drained, reducing lung function, circulation, and immune response—factors that all increase infection risk.

16 Autoimmune Reactions and Immune Exhaustion

This one is a combination effect of two I've mentioned already. Covid can lead to a vicious cycle of *immune exhaustion* and *autoimmune responses* that further depletes resources needed to defend against new infections.

I keep writing and rewriting that one, and it never quite explains properly what I'm trying to say, but I'm going to leave it like that and maybe come back to it later.

17 Bronchiectasis and Respiratory Vulnerability

Severe cases of Covid can lead to bronchiectasis—a condition where the airways become scarred and then more prone to filling with mucus that doesn't get cleared, providing a favourable environment for bacteria.

18 Disrupted Gut Microbiome

Covid disrupts the gut microbiome (the balance of microbes in your gut that live inside you helping you digest food and maintain a safe gut), weakening gut immunity and increasing vulnerability to gastrointestinal infections.

19 Loss of Appetite and Malnutrition Due to Nerve and Taste Damage

Damage to smell and taste can lead to malnutrition, stripping the body of immune-essential nutrients and increasing susceptibility to infections.

20 Higher Risk of Aspiration and Micro-aspiration

In severe cases (and yes, there are still plenty of severe cases), weakened swallowing muscles increase the risk of aspiration, leading directly to infections like aspiration pneumonia.

21 Cytokine Imbalances and Dysregulated Immune Signalling

One other side effect of Covid’s cytokine storm is that it can then cause misfiring immune responses, causing immune cells to respond ineffectively and leaving the body confused as to what it should and shouldn't attack.

22 Decreased Natural Killer (NK) Cell Activity

Covid infection can reduce NK cell activity, leaving the body less capable of responding to early-stage infections and clearing infected cells.

23 Increased Risk of Bacterial Overgrowth

That disruption of the respiratory and gut microbiome balance can allow *harmful* bacteria to grow unchecked.

24 Exhausted Signalling Pathways

The immune system needs to send signals round the body... and constant signalling demands placed on immune pathways in severe Covid cases lead to immune miscommunication, lowering the effectiveness of responses to new infections.

25 Infected Cells as Entry Points

Covid-infected cells can release particles that attract other pathogens, which increases the risk of subsequent infections in already affected tissues.

26 Tissue Damage from Macrophage Activity

Overactivated macrophages can damage healthy tissue while failing to effectively clear pathogens, leaving damaged tissue more vulnerable to bacterial or viral colonisation.

I knew I'd think of some more.

27 Weak Complement System

Covid can disrupt the complement system, the body's tagging system for killing pathogens.
With fewer pathogen tags, the body struggles to clear infections, especially bacteria in the bloodstream.

28 Low Interferon Production

Covid can stifle interferon production, the immune alarm that kick-starts antiviral defences.
Weak early defences make it easier for other viruses to sneak in and establish infections.

29 Chronic Immune Misfire (Long COVID)

Long Covid leaves the immune system in overdrive, with no clear target. Constant, wasted immune effort drains defences, leaving gaps for new infections.

30 Fewer Natural Defences on Mucosal Surfaces

Antimicrobial peptides, a kind of natural barrier to pathogens, can drop during Long Covid. Mucous membranes become less protected, inviting infections in the lungs and gut.

31 Reactivated Dormant Viruses

Lingering immune issues allow dormant viruses like Epstein-Barr or passive infections like TB to wake up and become active. Reactivated infections put even further strain on immunity, making more new infections more likely.

32 Gut Issues and “Leaky Gut”

Yeah, I know this one is a bit vague and messy.
Long Covid can mess with gut bacteria and increases gut permeability. Harmful bacteria slip through the gut wall, raising the risk of infections in the blood.

33 Weak Lungs and Poor Mucus Clearance

Long Covid often leaves lasting lung issues and poor mucus movement. Impaired lungs are easy targets for bacteria and viruses, especially pneumonia.

34 Extreme Fatigue and Sedentary Lifestyle

Chronic fatigue limits movement and lung exercise. Poor circulation and weak lung strength make infections more likely.

35 Nervous System Out of Sync

Dysautonomia from Long Covid messes up automatic functions like circulation and breathing. Weaker immune responses in the gut and circulation leave gaps for infections.

36 Lung Scarring and Stiffness

Covid infection can leave scarred, less flexible lung tissue (in different ways to the earlier mentioned bronchiectasis) Stiff lungs struggle to clear pathogens, increasing the risk of chronic infections.

I've probably missed something that I'll think of later...

Now...

COVID ISN'T THE ONLY VIRUS THAT CAN DAMAGE YOUR ABILITY TO FIGHT INFECTION...

You already know that.
Some common infections do some of these.
A common cold can damage your lung surfaces and make you more vulnerable to a bacterial infection.

That stuff is really common and obvious.

In fact... here's a list of a few other pathogens... viruses, bacteria, parasites, fungi... that are known to commonly cause *some* of these effects...

Influenza Virus: 1, 2, 3, 8, 11, 21, 23, 27, 28, 33

Streptococcus pneumoniae: 2, 10, 12, 13, 20, 33

Ebola Virus: 1, 3, 8, 11, 13, 24, 27, 28, 29, 33

HIV: 1, 4, 5, 6, 7, 12, 14, 16, 18, 22, 25, 27, 28, 29, 31, 35
Mycobacterium tuberculosis (TB): 1, 5, 8, 16, 17, 22, 24, 26, 29, 33
Measles Virus: 3, 4, 6, 14, 21, 28, 29
Parvovirus B19: 7, 8
Hookworm: 8, 18
Poliovirus: 9, 28, 34

Bordetella pertussis (Whooping Cough): 2, 10, 21, 33

Dengue Virus: 3, 11, 27, 28, 33

Cytomegalovirus (CMV): 4, 12, 15, 22, 29, 31

Streptococcus pyogenes: 2, 13, 21

Epstein-Barr Virus (EBV): 4, 6, 15, 22, 28, 29, 31

Hepatitis C Virus: 1, 8, 16, 18, 29, 35

Non-Tuberculous Mycobacteria (NTM): 17, 33

Clostridioides difficile: 8, 18, 32

Cancer-related Cachexia: 8, 19, 34

Sepsis (Various Bacteria): 1, 3, 8, 21, 24, 27, 33

Hepatitis B Virus: 4, 6, 14, 16, 25, 29, 31

Varicella-Zoster Virus (VZV): 4, 6, 15, 22, 28, 29, 31
Human Papillomavirus (HPV): 4, 6, 16, 29
Helicobacter pylori: 3, 8, 16, 32

Salmonella Typhi: 8, 18, 29, 32
Human T-cell Leukemia Virus (HTLV-1): 1, 4, 6, 7, 22, 29
Rubella Virus: 4, 6, 14, 27, 28, 29

Plasmodium falciparum (Malaria): 1, 8, 11, 16, 29, 32
Aspergillus fumigatus (Aspergillosis): 11, 18, 22, 33, 36
Mumps Virus: 4, 14, 15, 28, 29
Klebsiella pneumoniae: 2, 10, 12, 13, 20, 21, 33

Borrelia burgdorferi (Lyme Disease): 1, 3, 5, 8, 15, 16, 21, 22, 24, 29, 35
Cryptococcus neoformans: 4, 6, 7, 8, 22, 29, 36

Respiratory Syncytial Virus (RSV): 1, 2, 3, 10, 12, 21, 27, 33
Zika Virus: 4, 9, 15, 27, 28, 29, 35
Candida albicans: 18, 29, 32, 36

There's one pathogen for each effect that I've listed Covid as being able to cause.

And some of these viruses can do things that Covid *can't* do... we know that too.

But which virus can do everything from 1 to 36?

Covid.

And every Covid infection doesn't need to be able to do all of these to you to make you more vulnerable to infection.

And we don't know how long Covid infection can or will leave you with these effects.

And we don't know what the effects of multiple infections are.

But if you're going to deny that Covid infections can make you more vulnerable to other infections, then you're battling reality.

And it's not that there aren't other factors involved in the rise of other pathogens like these:

But if you deny that Covid infections are a factor, then again... you're just not living in reality.

Covid infections are making us *weaker* and *sicker*.

And multiple covid infections aren't going to stop that process.

The evidence is mounting that multiple covid infections make the effects... WORSE.

Reading this thread back this morning, and I feel like I oversimplified every point from 1 to 36.

Each one could be ten tweets.
😥

Well.
Feel free to use a search engine that you can ask "how does covid infection cause ________".