In a recent study published in Science, researchers found a low dose of the Moderna vaccine lasts for at least six months, and there is no indicator that vaccinated people will need a booster shot.
In fact, while the Moderna COVID-19 vaccine (mRNA-1273) led to strong CD4+ (helper) T cell, CD8+ (killer) T cell and antibody responses for at least six months after clinical trial participants were fully vaccinated, it is likely that the immune response could last much longer.
The researchers also showed that this strong immune memory lasted in all age groups tested, including in people over age 70, a demographic especially vulnerable to severe COVID-19.
The study is from La Jolla Institute for Immunology. One author is Daniela Weiskopf, Ph.D.
In the study, the team compared recovered COVID-19 patients to vaccine trial participants who received a 25-microgram dose of the Moderna vaccine during the phase 1 clinical trials.
This vaccine dose is a quarter of the 100-microgram Moderna dose given emergency authorization by the Food and Drug Administration (FDA).
While researchers didn’t know whether this smaller dose is as effective as the standard dose, this new study showed that the T cell and antibody response in the smaller dose group is still strong.
In fact, the researchers found that the Moderna vaccine spurs an adaptive immune response to the SARS-CoV-2 spike protein (a key target) nearly identical to the immune system’s response to a natural SARS-CoV-2 infection.
The study does not show that a lower dose of the Moderna vaccine provides the same protection as the standard dose.
The research also showed the power of “cross-reactive” T cells. In a 2020 study, the team showed that T cells in people who had recovered from common cold coronaviruses could respond to the novel coronavirus, SARS-CoV-2.
The researchers found that people with cross-reactive T cells had significantly stronger CD4+ T cell and antibody responses to both doses of the vaccine.
They say if you have this immune reactivity, your immune system may kick in faster against the virus. And multiple studies have shown that how quickly the immune system reacts is key.
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