A Columbia University study published Oct. 7 found the memory of COVID-19 infection is primarily stored in T and B cells in the lungs and surrounding lymph nodes.
Researchers studied the tissues of four COVID-19 survivors aged 11-74 who died of unrelated causes, prior to the release of vaccines, and compared them to the tissues of uninfected individuals.
The study found "robust" immune memory of new pathogens can be found in even older adults, despite the lack of T cells the immune system creates to do so after age 40.
"We know the immune system declines with age," said study head Donna Farber, PhD, the George H. Humphreys II Professor of Surgical Sciences and professor of microbiology & immunology at Columbia University Vagelos College of Physicians and Surgeons. "But that someone in their 70s could create a robust and long-lasting immunological memory response shows that parts of the immune system that we associate with younger ages still persists."
Researchers also found evidence that specialized sites, called germinal centers, were present within the lung-associated lymph nodes for up to six months after infection, even in older individuals.
"Our study suggests that to improve protection against the virus, vaccines should target the memory immune cells within the lung and its associated lymph nodes, which can be accomplished with nasal sprays of disabled viruses," Farber said. "We’ve found previously in mice with influenza that memory T cells in the lung are needed for optimal protection against respiratory infections, and this study strongly suggests that the same could be true in people."
Researchers are currently looking at the tissues of vaccinated donors to see if vaccine-induced memory is similar to memory created by natural infection.