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...
I've just been sitting with a family wrestling with a serious new onset health condition that came out of nowhere, and, of course, it's one that's made more likely by Covid infection.
And then one of them says,
"everyone has more health problems now, don't they..."
"... I'm not imagining it, am I? So many people seem to have problems like this. I know so many families with serious things going wrong. Is it just that we're hearing more about it now? Or are people having more health problems?"
And I could just hear that information vacuum that is begging to be filled.
*Authorised* illness absence:
still 37% up in Primary Schools
still 50% up in Secondary Schools
and 🚨 an astonishing 74% up in Schools for Children with Special Educational Needs and Disabilities.
The most vulnerable children, the children most in need of protection from infectious disease, and our government is just throwing them under the bus.
🤬
A penny has been trying to drop in my mind for a while, but it hasn't quite fallen yet. It's about how some of these simple-minded folk who have clawed their way in charge of public health organisations don't seem to be able to get their heads around complexity.
The reality of the situation with infectious disease is that different diseases transmit in different ways.
And different diseases have different short term and long term impacts.
Trump is a locked in Russian asset, run by Putin himself.
But just think for a moment how phenomenally hard that is to maintain - Trump is one of the most public people in the world.
Consider this for a moment...
Putin has to be constantly hyper-careful about communications with Trump.
Digital comms are dangerous due to *anyone* who might listen in.
Western intelligence agencies are no longer allies in this sense, but even then we've known that even allies listen in on each other's communications, especially when those communications are with Russia.
I see it year after year after year.
I first saw it in Spring 2020.
I see it over and over again now, in 2025:
People who catch Covid catch secondary infections far more often than they do after any other common virus.
And do you know what?
The governments see it too.
🧵
Let me show you.
Using some government data.
This handy chart comes at the end of the weekly 'flu and covid surveillance graphs' report published each week by the UKHSA - the UK Health Security Agency.
It's dancing at the edge of my ability to express it, but I have an intuitive sort of feeling that the current destruction of public health in America isn't a turnaround from the policies under Biden, but a natural next step of the progression.
I've been banging on for five years about the foolishness of ignoring the science of what Covid and other infections do to you.
And ignoring the harm caused by repeat covid infections always seemed to me a first step in ignoring the danger of all infections.