In a new study from Johns Hopkins Medicine, researchers found that immune system cells also known as helper T cells—produced by people who have received mRNA vaccines for COVID-19 also will recognize the mutant variants of the coronavirus.
This suggests that T cell responses elicited or enhanced by the vaccines should be able to control the current SARS-CoV-2 variants without needing to be updated or modified.
They also found that the same T cells may provide some protection from another member of the coronavirus family that is responsible for one type of the common cold.
CD4+ T cells get their “helper” nickname because they assist another type of immune cell, the B lymphocyte (B cell), in responding to surface proteins—antigens—on cells infected by invaders that include viruses such as SARS-CoV-2.
Activated by the CD4+ T cells, immature B cells become either plasma cells that produce antibodies to mark infected cells for disposal from the body or memory cells that “remember” the antigen’s biochemistry for a faster response to future infections.
The mRNA vaccines—known by their manufacturer’s names, Pfizer-BioNTech and Moderna—provide genetic instructions to a vaccinated person’s immune system to recognize the spike protein and start the production of antibodies against SARS-CoV-2.
In the study, the researchers evaluated blood samples from 30 healthy health care workers and laboratory donors who had not previously tested positive for SARS-CoV-2—both before and after two doses of a COVID-19 mRNA vaccine.
The researchers discovered that vaccine recipients—as expected—had broad T cell responses to the original strain SARS-CoV-2 spike peptides.
They identified 23 distinct T cell-targeted peptides, of which only four appear affected by the mutations that created the variant coronaviruses first seen in the United Kingdom and South Africa.
That means the other 19 peptides are the same in the original SARS-CoV-2 and the newer strains, so the mRNA vaccines should induce T cells that respond well to the variants.
The team says the T cells may help prevent the variant viruses from causing severe COVID-19 disease even if antibodies don’t stop them from infecting a person.
In a recent and related study, the team looked at blood from convalescent patients who had recovered from a SARS-CoV-2 infection and identified the unique receptors on memory CD4+ T cell that recognize the spike proteins of both the original strain of SARS-CoV-2 and four common cold coronaviruses.
The team says that characterizing these T cell receptors may be helpful in guiding the development of future vaccines for a variety of coronaviruses.
If you care about the COVID-19 vaccine, please read studies about why it takes 2 shots to make COVID-19 mRNA vaccines do their antibody-creating best and findings of Americans have unrealistic expectations for a COVID-19 vaccine.
For more information about the COVID-19 vaccine and your health, please see recent studies about how the body responds to the COVID-19 vaccine and results showing that one dose of vaccine may be enough for COVID-19 survivors.
The study is published in the Journal of Clinical Investigation. One author of the study is Joel Blankson, M.D., Ph.D.
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