Immunologists are beginning to suspect that T cells are playing a much bigger role in immunity against Covid-19 than previously realised after a string of recent papers.
Scientists have pointed to growing evidence that T cells may be the key to how long patients stay resistant to reinfection with Covid-19 and may be producing broader immunity in the population than antibody studies may suggest.
A paper in Nature by a group of scientists in Singapore found that patients with a history of SARS infection from 2003 still had T cell responses 17 years later and also cross-reactivity with Covid-19 (SARS-Cov-2).
They also detected SARS-Cov-2 specific IFN-γ responses in 19 out of 37 people who had not been exposed to either SARS virus, suggesting some T cell immunity may be conferred by exposure to other coronaviruses.
Another paper, published as a pre-print, found SARS-2-Cov specific T cells in patients who had mild or asymptomatic Covid-19 or whose family members had been infected but they themselves were antibody negative.
Professor Danny Altmann, Professor of Immunology at Imperial College London, said the paper added to the growing body of evidence that antibody testing alone under-estimates immunity.