Asymptomatic COVID-19 patients are mounting robust immune responses that differ from responses in those who become ill, according to a study that appears to contradict previous thinking by health experts. For the study, researchers compared quantities and function of SARS-CoV-2-specific T cells in 76 symptomatic COVID-19 patients and 85 infected individuals without symptoms. In a paper posted on bioRxiv ahead of peer review, they reported, "Frequencies of T cells specific for the different SARS-CoV-2 proteins in the early phases of recovery were similar" in the two groups. However, the asymptomatic group had increased production of interferon-gamma and interleukin-2 after activation of SARS-CoV-2-specific T cells in blood. "This was associated with a proportional secretion of IL-10 and pro-inflammatory cytokines (IL-6, TNF-alpha and IL-1beta) only in asymptomatic infection, while a disproportionate secretion of inflammatory cytokines was triggered by SARS-CoV-2-specific T cell activation in symptomatic individuals," the researchers wrote. "What we still need to understand is whether those T cells can persist over time and offer long-term immunity," coauthor Antonio Bertoletti of Duke-NUS Medical School, Singapore told Reuters. —Reuters Staff Source
