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Zdenek Vrozina Profile picture
Zdenek Vrozina
@ZdenekVrozina
Health Care Consulting
4 subscribers
Aug 5 • 21 tweets • 3 min read
Can COVID-19 cause lasting heart changes in children - even after a mild case?
Yes.
A new peer-reviewed study followed kids after infection.
The shocking part? Just how many still show signs of heart dysfunction years later.🧵 Even in children who had mild COVID, researchers found measurable - and persistent changes in heart function and blood pressure.
These weren’t isolated cases.
Some of the effects were detectable years after infection.
Aug 4 • 8 tweets • 2 min read
What do we really know about COVID-19 vaccines and long COVID?
A meta-analysis from Robert Koch Institute analyzes 65 studies (5.7M people) to answer one critical question:
Do vaccines reduce the risk of long COVID when given before infection?
Short answer: Yes - but two key problems remain.🧵 Post-COVID condition (PCC; symptoms ≥3 months):
Vaccine effectiveness (VE): 41% (95% CI: 27.8–51.7%)
Long COVID (LC; symptoms ≥4 weeks):
VE: 34.1% (95% CI: 25.0–42.2%)
Effectiveness increased with dose count:
1 dose: 19%
2 doses: 43%
3 doses: 70% (based on one study)
Lower VE was observed:
in children (26%)
after Omicron infection: only 21% (CI –10% to +43%) - based on just two studies, but suggests that vaccines may be far less protective against long COVID after Omicron - especially in younger or previously exposed populations.
But two key factors limit how we interpret this data:
Jul 30 • 13 tweets • 3 min read
What if long COVID (and ME/CFS) aren’t just consequences of damage or infection - but symptoms of a survival program that never shut off?
A new review in Cell Reports Medicine, 2025 says:
These conditions might be stuck in an ancient biological response.
Let’s unpack that. 🧵 The idea sounds bold, but it’s well grounded.
Komaroff and Dantzer suggest that many long COVID symptoms reflect a deeply wired program - the same one that makes us rest, isolate, and lose appetite when we’re sick.
In other words: this isn’t dysfunction only. It’s function gone chronic.
Jul 29 • 16 tweets • 3 min read
Pediatric immunity after COVID-19: new evidence of antibody dysfunction and autoimmunity.
A new study from the US shows that even mild SARS-CoV-2 infection in children can leave behind an immune imprint - including the production of autoantibodies and impaired antibody function.🧵 Researchers analyzed 139 children with various clinical presentations - from asymptomatic and mild cases, to severe COVID-19 and MIS-C. They compared them to 28 healthy controls.
More than half of the infected children had detectable autoantibodies. In healthy kids? Just 14%! That’s a strong signal.
Jul 29 • 12 tweets • 3 min read
New study confirms a key Long COVID immune signature:
shift toward Th2 and Th17 T cell responses
immune imbalance
thymus reactivation
The title says “recovery” - but 1 in 3 had persistent symptoms.
And they showed the clearest immune disruption.🧵 Researchers analyzed blood samples from people with:
acute COVID
past COVID
Long COVID
healthy controls
They profiled T cell subsets (CD4, CD8, memory states)
And crucially - they measured TREC, a marker of thymic activity.
Jul 27 • 13 tweets • 2 min read
Tired months after COVID?
A study found that even 11 months later, many people still show impaired mitochondrial function in their immune cells - a possible driver of long COVID symptoms.
And yes, even after mild infections.🧵 Researchers measured mitochondrial membrane potential (ΔΨm) - a key indicator of cellular energy - in blood immune cells (PBMCs) from:
healthy controls
people with active COVID
recovered after 40 days (R1)
recovered after 11 months (R2)
Jul 24 • 12 tweets • 2 min read
A massive new study in Nature Communications (2025) looked at over 1.2 million kids and teens to answer a key question:
Does COVID-19 infection itself increase the risk of mental health problems in young people?
Short answer: Yes - slightly, but measurably.
Let’s break it down.🧵 The study followed children (5–11) and adolescents (12–20) across 25 major hospitals in the U.S., comparing
326,074 COVID+ patients
887,314 COVID− patients
All matched for background risk factors. Outcomes were tracked 1-6 months post-infection.
Jul 24 • 16 tweets • 3 min read
What if mild variants are just better at hiding? SARS-CoV-2, MHC-I suppression, and virus-induced immunodeficiency🧵 SARS-CoV-2 - especially Omicron – suppresses MHC-I presentation in infected cells.
This mechanism qualifies as a form of virus-induced immunodeficiency, with direct implications for antiviral defense, viral persistence, and long-term outcomes.
Jul 23 • 12 tweets • 2 min read
Pediatric long COVID lasts for years - and leaves an immune fingerprint.
A new longitudinal preprint by Brunner-Weinzierl et al. (2025) shows that symptoms persist in some children for up to 3 years, and crucially: biomarkers don't improve over time - some worsen.🧵 Limitations? Yes:
Preprint (not peer-reviewed yet)
Control group = some children with CF
Small subgroup sizes
Still, it’s the detailed immune-metabolic study of pediatric LC.
Jul 22 • 7 tweets • 2 min read
This study brings direct evidence that replication-competent SARS-CoV-2 can persist in the brainstem of living mammals for at least 80 days after infection!
A major milestone in understanding the biology of long COVID.🧵 Researchers infected golden hamsters with Wuhan, Delta, and Omicron/BA.1 variants.
On day 80 - long after symptoms were gone - they sampled the brainstem.
In most animals, they isolated live, infectious virus capable of replication in cell culture.
Jul 22 • 25 tweets • 5 min read
What connects the lungs and blood vessels two years after COVID-19?
A new Brazilian study followed patients with persistent symptoms more than two years post-infection. What they found was striking: measurable damage in both lungs and vessels – and a clear link between the two.🧵 The study looked at 32 individuals with long COVID symptoms, about 32 months after their initial infection.
They tested:
Lung function (FEV1/FVC, KCO)
Endothelial function (via flow-mediated dilation - FMD)
Post-COVID functional status (PCFS scale)
Jul 20 • 9 tweets • 2 min read
Late but finally.
Top researchers (NIH, Yale, Karolinska, UCSF…) are now calling for a shift in how we run acute COVID-19 trials:
We must start measuring viral persistence as a biological outcome - even during the initial infection phase🧵 The logic draws from decades of experience with HIV, HCV, and precision oncology:
Chronic viral reservoirs are real
They’re hard to detect
And they require tailored, often combined therapies to target
Sound familiar?
Jul 19 • 16 tweets • 3 min read
ASHRAE 241: What to do when a virus spreads through the air.
This standard defines how much clean air per person is needed to reduce infection risk - but only during outbreaks.
It doesn’t apply all the time.
Here’s what it says and why it matter🧵 ASHRAE 241-2023 was created for times when viruses are spreading in the community.
It activates a special mode called IRMM - Infection Risk Management Mode.
That means
This is for outbreaks, not everyday conditions.
Jul 18 • 18 tweets • 3 min read
Viruses like HIV and CMV don’t just evade immunity - they reshape the host from within.
One way they do it? By targeting the cell’s ability to make proteins.
SARS-CoV-2 belongs in this group. It interferes with how ribosomes are made and used.
What that means - and why it matters 🧵 Viruses like HIV are known to:
block protein translation
rewire cell signaling
change cellular behavior without altering DNA
SARS-CoV-2 does the same.
Its Nsp1 protein hijacks ribosomes - the core machinery that turns RNA into protein.
Jul 17 • 14 tweets • 3 min read
This new Nature Immunology study is wild.
Turns out, CD8+T cells can go into an exhausted-like state without any chronic infection.
No persistent virus. No repeated antigen.
Just broken mitochondria.
Complex III.🧵 Quick recap: Complex III is part of the mitochondrial electron transport chain.
It pumps protons (ATP), passes electrons (metabolism), and makes ROS (signaling).
The authors knocked it out in T cells. What happened?
Jul 16 • 20 tweets • 5 min read
SARS-CoV-2 targets mitochondria. That’s not collateral damage - that’s a strategy.
A July 2025 review in Redox Biology brings together striking evidence of viral mitochondriopathy in COVID-19 and Long COVID.🧵 It shows how SARS-CoV-2 reprograms host cells by attacking their energetic and immunologic core: the mitochondria.
Here’s what that means:
Jul 15 • 15 tweets • 3 min read
What if the brain doesn’t just suffer from what “leaks in” - but from what no longer gets in?
A 2025 Nature Medicine study reframes brain barriers as dynamic gates - and may help explain post-COVID cognitive symptoms.🧵 Brain barriers are not passive walls.
They’re regulated, selective gates - deciding which proteins from blood enter cerebrospinal fluid (CSF), and under what conditions.
This study profiled 2,304 proteins in paired CSF/plasma samples from over 2,000 individuals!
Jul 15 • 13 tweets • 3 min read
Long COVID can injure the brain - and persistent autoimmunity could be a major driver.
A study links persistent AT1 receptor autoantibodies (AT1-AA) with neuroaxonal injury and cognitive symptoms.
Here’s what it means🧵 The study focused on post-COVID patients with neurological symptoms like brain fog, memory issues, or fatigue.
They found:
Elevated AT1-AA in serum and cerebrospinal fluid (CSF)
Correlation with neurofilament light chain (NfL), a marker of axonal damage
Signs of a compensatory immune response - often insufficient
Jul 14 • 12 tweets • 2 min read
SARS-CoV-2 is not just another respiratory virus.
It has evolutionarily selected features that actively manipulate innate immunity - similar to viruses like HIV, EBV, or CMV.
A new study in iScience shows how.🧵 What are formyl peptide receptors (FPRs)?
They’re innate immune sensors on neutrophils and other immune cells.
They detect signs of infection or damage.
Key types
FPR1: strongly pro-inflammatory
FPR2: dual, context-dependent
FPR3: poorly understood, but active in viral immunity
Jul 12 • 11 tweets • 2 min read
New study identifies 3 cognitive phenotypes in Long COVID - and raises a troubling question about insight and impairment.
123 adults
21 months post-COVID
All with some persistent cognitive complaints🧵 Participants:
Lab-confirmed SARS-CoV-2 infection
At least 3 months post-infection (median: 21 months)
Clinically significant cognitive complaints (eg attention, memory, planning)
No prior neurological or psychiatric diagnoses
Inclusion based on validated questionnaires: BRIEF-A & MMQ
Jul 11 • 12 tweets • 2 min read
A new prospective cohort study (Nature Communications, 2025) followed 74,000 adults in Southern China and found - elevated EBV activity (measured by VCA-IgA) significantly increases the risk of several cancers.
First - limitations.🧵 Conducted in an NPC-endemic region with unique viral and population genetics
VCA-IgA was measured only once - no longitudinal antibody data
Lymphomas and other cancers were grouped, not stratified by subtype