Jack - amatica health

Main paper: doi.org/10.1016/j.ij...

Overall, this paper is a strong signal that immune cell patterns in this tested population stayed shifted for a long time after the big wave, especially T cells, and maybe much more in heart and blood vessel disease. It does not prove every person stayed impaired.

Limits matter. This was a hospital-tested group, not a random sample. Infection was inferred from timing, not confirmed for each person. Repeat infections and new virus versions were not fully tracked. Most patients were Han Chinese. The pre-wave heart group was small.

This study does have strengths. It used a very large sample, 3 hospitals, shared lab methods, and a useful before-during-after setup because China had limited spread before late 2022. That makes the population-level comparison unusually informative.

But this study did not directly test those causes or track symptoms, so it cannot show these blood test changes caused long COVID symptoms. The paper also says older age and male sex may shape slower immune recovery.

The authors think these changes may matter for long COVID. They discuss possible reasons like lingering virus or virus pieces, sleeping viruses turning back on, the immune system attacking the body by mistake, and blood vessel injury.

By Aug 2024 in that group

total T cells were 72.9% below pre-wave levels
CD4 T cells 74.1% below
CD8 T cells 68.6% below
NK cells 46.3% below

The authors suggest immune exhaustion could be involved, meaning the immune system may be worn down.

In the month-by-month heart and blood vessel analysis, Mar to Jul 2023 looked roughly back to pre-wave levels. Then from Aug 2023 onward, several immune cell counts dropped to about one-third of earlier levels and stayed very low through Aug 2024

In the post-wave heart and blood vessel group, typical counts fell sharply versus pre-wave:

total T cells 1087 to 321
CD4 T cells 613 to 177
CD8 T cells 360 to 115
NK cells 214 to 109
B cells 145 to 109.

The most dramatic finding was in people with cardiovascular disease, meaning heart and blood vessel disease. In this group, lung disease looked similar to the overall pattern, but heart and blood vessel disease looked much worse.

B cells and NK cells were less steady month to month, but they were often lower too. So the clearest long-running signal in this paper was persistent lower T-cell levels at the population level.

Looking month by month, the T-cell findings lasted a long time. By Aug 2024, CD8 T cells were still 9.9% below the earlier pre-wave level. Total T cells were 5.2% lower, and CD4 T cells were 4.4% lower.

The typical post-wave values were still lower than pre-wave on the blood test:

CD4 T cells 672 to 607
CD8 T cells 463 to 406
total T cells 1227 to 1113
NK cells 218 to 195

The changes were more obvious in men and in people aged 41 to 80.

After the wave, some values partly improved, but many still had not returned to the earlier pre-wave level.

The actual numbers of CD4 T cells, CD8 T cells, total T cells, and NK cells were still lower than before the wave.

More people also tested below normal during the wave:

B cells 36.4% to 42.6%
CD4 T cells 23.3% to 43.2%
CD8 T cells 4.2% to 14.7%
NK cells 18.4% to 25.4%
total T cells 12.0% to 30.9%.

At the same time, some percentages went up, including B cells, NK cells, and the CD4/CD8 balance, meaning the mix between those 2 T-cell groups.

That is not a contradiction. A group can take up a bigger share even while its number falls, if other groups fall even more.

During the big wave, the actual numbers of major immune cells fell. That included total T cells, CD4 T cells, CD8 T cells, B cells, and NK cells.

So the main picture during acute spread was fewer of these cells circulating in blood.

They checked whether the pre-wave starting point was steady by comparing 2021 with most of 2022, and they did not find major differences. The 3 hospitals used the same lab method and shared standards, and extra checks with same-sized groups still showed the same pattern.

One important caveat is that this was not the same people tested again and again. It compared different groups of hospital patients at different times. So it shows population-level shifts, not that every person stayed different for 20 months.

They split the data into 3 time periods:

before the big wave, during the wave, and after the wave. Before = Jan 2021 to Nov 2022. During = Dec 2022 to Feb 2023. After = Mar 2023 to Aug 2024.

The researchers used records from 3 hospitals in Jinan, China. They included 40,537 adults who had this blood test from Jan 2021 to Aug 2024. They excluded people whose immune tests could be heavily changed by things like ICU care, cancer, pregnancy, or transplant.

The paper looked at lymphocytes, which are white blood cells that help fight infection.

T cells help organize the response and can kill infected cells.
B cells make antibodies.
NK cells are fast-acting white blood cells.
CD4 and CD8 are two main T-cell groups.

A study of 40,537 people found key immune cells that fight infections were still below earlier levels up to 20 months after the major COVID wave. In people with heart and blood vessel disease, some of these cells were about 70% lower than earlier levels.

Sadly I use a few platform that allows me to cross post on X/threads/Bluesky, so the platform specific edits aren’t as possible.

Full paper

link.springer.com/article/10.1...

The authors say larger studies are needed to confirm the findings and test whether this metabolite pattern could become a clinical biomarker for Long COVID.

Replication in independent cohorts is essential.

The metabolomics approach was also targeted, meaning researchers measured predefined molecules rather than scanning the entire metabolome
.
Other important metabolic changes could exist but were not measured.

There are also important limitations.

The study is small.

Only 42 participants.

All were survivors of severe ICU COVID.

Results might not apply to milder cases.

The authors say this metabolic pattern might help explain symptoms like fatigue and reduced physical capacity.

But this study cannot prove cause and effect.

It only shows associations between metabolites and symptoms.

Mitochondria are the structures inside cells that produce energy.

If mitochondria do not work properly, cells may shift toward less efficient energy pathways.

This can lead to changes in metabolites such as lactate and TCA intermediates.