Low-dose Moderna COVID-19 vaccine can trigger a long-lasting immune response

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CLow-dose Moderna Covid-19 vaccine can trigger a long-lasting immune response

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Low-dose Moderna Covid-19 vaccine can trigger a long-lasting immune response.

In a new study, researchers from the La Jolla Institute of Immunology (LJI) in the United States helped answer the question: How long can the vaccinated person’s immunity to COVID-19 last?

They report that the immunity produced by the low-dose Moderna mRNA-1273 COVID-19 vaccine can last at least six months, and there is no sign that vaccinators need booster injections.

The relevant research results were published online in the journal Science on September 14, 2021. The title of the paper is “Low-dose mRNA-1273 COVID-19 vaccine generates durable memory enhanced by cross-reactive T cells”.

Dr. Daniela Weiskopf, the co-corresponding author of the paper and LJI research assistant professor, said, “This time point is critical, because at this time the real immune memory has been formed.” The other two co-corresponding authors of the paper are Professor Alessandro Sette and Professor Shane Crotty of LJI.

In fact, although the Moderna mRNA-1273 COVID-19 vaccine caused a strong CD4+ (helper) T cell, CD8+ (killer) T cell and antibody response at least 6 months after the clinical trial participants were fully vaccinated, this immunity The reaction is likely to last longer. The authors also found that this strong immune memory persisted in all age groups tested, including people over 70 years old, a group that is particularly vulnerable to severe COVID-19.

Crotty added, “Immune memory is very stable, which is impressive. This is a good indicator of the durability of mRNA vaccines.”

Compare Moderna vaccine to natural immunity

The authors compared recovered COVID-19 patients with trial participants who received a dose of 25 micrograms of Moderna’s COVID-19 vaccine during the phase 1 clinical trial. The first author of the paper and LJI postdoctoral researcher Jose Mateus Triviño said, “We want to see if a quarter of the dose can induce any immune response. We have the opportunity to receive samples from the original Moderna/NIH Phase 1 trial participants. They received two injections of 25 micrograms of Moderna vaccine, 28 days apart.”

This vaccine dose is one-fourth of the 100 micrograms Moderna COVID-19 vaccine authorized by the U.S. Food and Drug Administration (FDA). Although these authors do not know whether this smaller dose is as effective as the standard dose, this new study shows that the T cell and antibody response in the smaller dose group is still strong.

Transmission electron microscope images of SARS-CoV-2, a novel coronavirus infection (coronavirus that causes COVID-19) isolated from American patients, showed that virus particles appeared on the surface of cells cultured in the laboratory. The name of the coronavirus is derived from the crown spikes on the outer edge of the virus particle. The picture is from NIAID-RML.

In fact, these authors found that Moderna’s COVID-19 vaccine stimulated an adaptive immune response to the SARS-CoV-2 spike protein (a key target), almost the same as the immune system’s response to SARS-CoV-2 natural infection. Weiskopf said, “This immune response is comparable. It is neither high nor low.”

This new study does not show that the lower dose of Moderna’s COVID-19 vaccine provides the same protection as the standard dose. Crotty said, “This will require a clinical trial to tell how protective the low dose is.”

The common cold coronavirus does prepare the immune system

This new study also shows the power of “cross-reactive” T cells. In a 2020 study published in the journal Science, the LJI team showed that the T cells of people who have recovered from the common cold coronavirus can respond to the new coronavirus SARS-CoV-2 (Science, 2020, doi: 10.1126/science.abd3871). At the time, they didn’t know whether this cross-reactivity could really protect people from COVID-19. Sette said, “It is important to understand the role of cross-reactive T cells because T cells play an important role in controlling and resolving COVID-19 infections.”

For this new study, these authors found that people with cross-reactive T cells had significantly stronger CD4+ T cell and antibody responses to both doses of Moderna’s COVID-19 vaccine. Sette said, “If you have this immune reactivity, your immune system may start to fight the virus faster. There have been multiple studies showing that the immune system’s response speed is the key.”

Moderna’s COVID-19 vaccine activates “killer” T cells

The team also filled an important gap in COVID-19 vaccine research. So far, many studies have shown effective CD4+ T cell responses to Moderna’s COVID-19 vaccine, but data on CD8+ T cell responses are lacking. Mateus Triviño said, “We know that people who are naturally infected and recovered have a good CD8+ T cell response to SARS-CoV-2; however, people are worried about the CD8+ T cells produced by the mRNA vaccine.”
Sette said that the new study showed a strong CD8+ T cell response to the low-dose Moderna Covid-19 vaccine, similar to the response of patients to natural SARS-CoV-2 infection. Weiskopf added, “We have seen a strong CD8+ T cell response — we have proven this with a variety of detection methods.”

Next, Weiskopf and her colleagues are investigating whether this vaccine persistence also applies to other types of COVID-19 vaccines? At the same time, Weiskopf said, real-world data show that immune memory can indeed be sustained. They are also interested in the durability of Moderna’s COVID-19 vaccine compared to other COVID-19 vaccines in use.

Reference: Low-dose Moderna Covid-19 vaccine can trigger a long-lasting immune response
Jose Mateus et al. Low-dose mRNA-1273 COVID-19 vaccine generates durable memory enhanced by cross-reactive T cells. Science, 2021, doi:10.1126/science.abj9853.

(source:internet, reference only)

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