Covid vaccine: Study shows why second dose of jab shouldn’t be skipped

This Morning: Eamonn Holmes discusses Covid vaccine

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The second dose of a COVID-19 vaccine induces a powerful boost to the part of the the immune system that provides widespread antiviral protection, according to a study. A team of researchers at the Stanford University School Medicine set out to find out exactly what affects the vaccine has on the numerous component of the immune response.

The study, published in Nature, looked blood samples from individuals inoculated with the vaccine.

Blood was drawn from 56 healthy volunteers at multiple time points preceding and following the first and second shots.

Researchers observed that the first shot increases COVID-19 specific antibody levels, but not nearly as much as the second does.

Bali Pulendran, PhD, professor of pathology and of microbiology and immunology said: “The second shot has powerful beneficial effects that far exceed those of the first shot.

“It stimulated a manifold increase in antibody levels, a terrific T-cell response that was absent after the first shot alone, and a strikingly enhanced innate immune response.”

Pulendran and his team assessed activity among the immune cells influenced by the vaccine.

They counted antibodies and measured levels of immune-signalling protein.

The researchers observed that immune cells that don’t attach themselves to viral particles as antibodies but rather probe the body’s tissue for telltale signs of viral infections. On finding them, they tear those cells up.

Pulendran said: “The world attention has recently been fixed on COVID-19 vaccines, particularly on the new RNA vaccines.

“This is the first time RNA vaccine have ever been given to humans, and we have no clue as to how they do what they do: offer 95% protection against COVID-19.

“Despite our outstanding efficacy, little is known about how exactly RNA vaccines work.”

The immunological basis for approval of vaccines is their ability to induce neutralising antibodies that can tack themselves to a virus and block it from infecting cells.

Pulendran stressed the importance of the innate immune system in combatting infection.

He explains that the ‘body’s sixth sense’ is now understood to be of immense importance.

He added: “Antibodies are easy to measure, but the immune system is much more complicated than that. Antibodies alone don’t come close to fully reflecting its complexity and potential range of protection.”

During the week or so it takes for the adaptive immune system to rev up, innate immune cells perform the mission-critical task of holding infections at bay by gobbling up whatever they may believe to be a pathogen.

The findings come as every adult in the UK has been offered a first dose of a COVID-19 vaccine, hitting the Prime Minister’s target ahead of schedule.

More than 82,413,766 doses have been administered in the UK with 87.9 percent receiving a first dose and 68.5 percent receiving both vaccines.

Data from Public Health England (PHE) show COVID-19 vaccines are highly effective against hospitalisation from the Delta variant.

The analysis shows the Pfizer-BioNTech is 96 percent effect and the Oxford-AstraZeneca vaccine is 92 percent effective against hospitalisations after two doses.

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