mRNA Vaccine Stays Active in the Body Longer Than Expected, New Data Shows. Is This Dangerous?


No, vaccine persistence in the lymph nodes may actually aid immunity formation instead.
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Earlier this year, a study published in Cell, a highly esteemed journal, found that the mRNA genetic material and spike protein persist in the lymph nodes of individuals who got the mRNA vaccine for up to two months.

Such findings contradict the concept of the fragile mRNA vaccine, which degrades quickly and doesn’t last long in the body, thus making long-term side effects unlikely.

This contradiction has garnered much traction on Twitter, where people are again questioning the long-term safety of the mRNA vaccine.

Now, how should we interpret this study?

To state the conclusion early, the study showed that the mRNA vaccine stays active for up to two months in the lymph nodes only, not anywhere else, not the brain, heart, ovaries, etc. Lymph nodes are one of the main sites of immunity formation, so it’s not very surprising that vaccine activities persist in the lymph nodes.

What the study did and found?

In this study, Röltgen et al. from Stanford University, U.S., sought to compare immune responses in the lymph node’s germinal center of people who were vaccinated or infected with SARS-CoV-2.

Lymph nodes are small bean-shaped structures found throughout the lymphatic vessels of our body, where immune cells are found. Specifically, T-cells and antibody-secreting B-cells are found in the paracortex and germinal centers, respectively, of lymph nodes (Figure 1):
Wikimedia (left) and Nature 2006 (Right).

Röltgen et al. extracted a portion of:

  • Peribronchial lymph node (near the lungs) from seven patients who died from Covid-19 at 1–3 weeks after symptom onset (via autopsy).
  • Axillary lymph node (near the armpit of the vaccinated arm) from seven individuals vaccinated with mRNA vaccine 1–8 weeks ago (via biopsy).
  • Controls: Thoracic lymph node (near the throat) from patients who died from pneumonia before the Covid-19 pandemic via autopsy, and axillary lymph node from unvaccinated individuals who underwent biopsy for other clinical purposes.

And they found that:

  • Lymph nodes and germinal centers were more deformed in Covid-19 patients, with disrupted T-cell and B-cell responses, compared to mRNA-vaccinated individuals.
  • Likewise, lymph nodes were more developed in mRNA-vaccinated individuals, with fully functioning and robust T-cell and B-cell responses, compared to Covid-19 patients.
  • Vaccine-specific mRNA was detected in the lymph node’s germinal centers collected on days 7, 16, and 37 — with lower signals on day 60 — after vaccination, which was absent in Covid-19 and control samples.
  • Vaccine-specific spike protein was detected in the lymph node’s germinal centers on day 16 — with a lower signal on day 60 — after vaccination, but the amount varied substantially between individuals.
  • Vaccine-specific spike protein was detected in the plasma of vaccinees on days 1–2 (93% of vaccinees, median spike concentration of 47 pg/mL), but the amount dropped rapidly to negative on days 7 (67% of vaccines, 1.7 pg/mL) and 21 (50% of vaccinees, 1.2 pg/mL) (figure 4).

Overall, Röltgen et al. showed that:

  • The lymph nodes of individuals who got the mRNA vaccine are in much better condition, both structurally and functionally, than individuals who got fatal Covid-19.
  • This is despite that vaccine-specific mRNA genetic material and spike protein were found in the lymph nodes of vaccinated individuals (for up to 2 months), indicating that such occurrence poses no harm to the lymph nodes. The authors hypothesize that vaccine persistence in the lymph nodes are supporting the formation of longer-lasting immunity.
  • While vaccine-specific spike protein was detected in the plasma (a blood component) of vaccinated individuals on days 1–2, the spike protein quickly dropped to negligible amounts after that.

What does it mean for the long-term safety of the mRNA vaccine?

In essence, the crux of this study is that the mRNA vaccine’s activities persist in the lymph nodes for up to two months (possibly longer as the study only lasted for two months), but this poses no harm to the lymph nodes and it may, in fact, aid immunity formation instead.

“[We] observed extended presence of vaccine mRNA and spike protein in vaccinee LN GCs [lymph node germinal centers] for up to 2 months after vaccination,” Röltgen et al. wrote. “We hypothesize that the abundant spike antigen in the GCs of mRNA vaccine recipient LNs may contribute to the increased breadth of viral variant RBD [receptor binding domain] binding by IgG [immunoglobulin G, a type of antibody] seen after vaccination.”

The director of this study, Scott D. Boyd, MD, Ph.D., a pathology professor, said in a tweet, “In our study, finding SARS-CoV-2 spike protein in the lymph nodes of vaccine recipients gives some evidence for why the vaccines are working well. Lymph nodes are the desired destination for vaccine antigens, because that is where antibody producing responses are organized.

Finding some vaccine RNA in lymph nodes may help to explain why the viral spike protein is present there for longer times. We don’t have any evidence that this is a harmful event.”

Röltgen et al.’s findings are also in line with what previous mRNA vaccine biodistribution research shows, which I covered here and here.

For example, one of the highly cited mRNA biodistribution studies in rats from the European Medicines Agency (EMA) stated that,

“Low levels of mRNA could be detected in all examined tissues except the kidney. This included heart, lung, testis and also brain tissues, indicating that the mRNA/LNP [lipid nanoparticle] platform crossed the blood/brain barrier, although to very low levels (2–4% of the plasma level)…. The mRNA constructs were not measurable after maximum 3 days in tissues other than the muscle, lymph nodes, and spleen (~25 hours in brain).”

So outside of certain immune-related organs — such as the muscle, spleen, and lymph nodes — the mRNA vaccine no longer persists after three days, at least in rats. The muscle cells, i.e., the injection site, express the spike protein important for immunity formation, whereas the spleen and lymph nodes are part of the lymphatic system that stores immune cells.

Röltgen et al.’s paper is not without limitations. First, sample sizes are small: seven vaccinees (alive) and seven Covid-19 patients (deceased), with the latter group comprising fatal cases of Covid-19. Second, comparing different lymph node sites — axillary (armpit) in vaccinees and peribronchial (lungs) in Covid-19 patients — may not be entirely fair either. Third, organs other than the lymph nodes were not studied for mRNA vaccine persistence.

Despite these limitations, an important finding of this paper still stands — that mRNA vaccine persists, but doesn’t harm the lymph nodes and likely aids immunity formation.

But anti-vaccine supporters will tell you that Röltgen et al.’s paper is evidence that authorities lied about how long the mRNA vaccine lasts in the body, as well as the long-term safety of the mRNA vaccine.

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MSc Biology student | 7x first-author academic papers | 200+ articles on coronavirus | Freelance medical writer


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