NIH: Moderna COVID-19 vaccine generates long-lasting immune memory cells

LOS ANGELES - The Moderna COVID-19 vaccine represented strong immune memories of the novel coronavirus six months after receiving a second dose, according to a recent report from the National Institutes of Health. 

When NIH researchers discuss immune memories, they are referring to immune cells called T cells that retain viral data and linger in the body helping fight off against unwanted illnesses like COVID-19. 

The report was published on Oct. 5 and sheds light on how lasting immunity against COVID-19 develops after vaccination. 

A team of researchers analyzed data from 35 participants enrolled in phase 1 clinical trial of the Moderna vaccine and followed up six months after their final dose. 

RELATED: Moderna: Vaccine 93% effective up to 6 months but booster likely needed before winter

Measuring the participant's T cell levels, researchers found a strong presence even among participants over 70 years of age. 

These memory cells were present in every participant well over six months after their second dose of the vaccine.

Research lead Shane Crotty called the findings impressive. 

"The immune memory was stable, and that was impressive," Crotty says. "That’s a good indicator of the durability of mRNA vaccines."

In August, Moderna said their own research found that their vaccine remained 93% effective against symptomatic illness six months after the second dose, but amid the ongoing spread of the highly contagious delta variant, the company said it believes a booster dose will be necessary prior to the winter season.

Moderna said it believes the ongoing spread of the delta strain combined with more people gathering indoors as it gets colder will "lead to an increase of breakthrough infections in vaccinated individuals."

"While we see durable Phase 3 efficacy through 6 months, we expect neutralizing titers will continue to wane and eventually impact vaccine efficacy," the company said. "Given this intersection, we believe dose 3 booster will likely be necessary prior to the winter season."