In a new study from La Jolla Institute for Immunology, researchers help answer the question: how long does immunity against COVID-19 last in vaccinated people?
They 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.
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 new study does not show that a lower dose of the Moderna vaccine provides the same protection as the standard dose.
The new 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.
The team also filled in an important gap in COVID-19 vaccine research. They show a strong CD8+ T cell response to the low dose Moderna vaccine, similar to the response after a patient fights a natural SARS-CoV-2 infection.
If you care about COVID vaccines, please read studies about this new COVID-19 vaccine can give the body ‘border protection’ and findings of Pfizer vaccine may protect against COVID variants in these people.
For more information about COVID vaccines and your health, please see recent studies about these old vaccines can fight COVID-19 pandemic and results showing that one dose of Pfizer vaccine may effectively protect people who’ve had COVID.
The study is published in Science. One author of the study is Daniela Weiskopf, Ph.D.
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