{Reference Type}: Journal Article
{Title}: Lower Humoral and Cellular Immunity Following Asymptomatic SARS-CoV-2 Infection Compared to Symptomatic Infection in Education (The ACE Cohort).
{Author}: Hopkins G;Gomez N;Tucis D;Bartlett L;Steers G;Burns E;Brown M;Harvey-Cowlishaw T;Santos R;Lauder SN;Scurr M;Capitani L;Burnell S;Rees T;Smart K;Somerville M;Gallimore A;Perera M;Potts M;Metaxaki M;Krishna B;Jackson H;Tighe P;Onion D;Godkin A;Wills M;Fairclough L;
{Journal}: J Clin Immunol
{Volume}: 44
{Issue}: 6
{Year}: 2024 Jun 10
{Factor}: 8.542
{DOI}: 10.1007/s10875-024-01739-0
{Abstract}: <B>OBJECTIVE: </B>Asymptomatic SARS-CoV-2 infections were widely reported during the COVID-19 pandemic, acting as a hidden source of infection. Many existing studies investigating asymptomatic immunity failed to recruit true asymptomatic individuals. Thus, we conducted a longitudinal cohort study to evaluate humoral- and cell-mediated responses to infection and vaccination in well-defined asymptomatic young adults (the Asymptomatic COVID-19 in Education [ACE] cohort).<BR><B>METHODS: </B>Asymptomatic testing services located at three UK universities identified asymptomatic young adults who were subsequently recruited with age- and sex-matched symptomatic and uninfected controls. Blood and saliva samples were collected after SARS-CoV-2 Wuhan infection, and again after vaccination. 51 participant's anti-spike antibody titres, neutralizing antibodies, and spike-specific T-cell responses were measured, against both Wuhan and Omicron B.1.1.529.1.<BR><B>RESULTS: </B>Asymptomatic participants exhibited reduced Wuhan-specific neutralization antibodies pre- and post-vaccination, as well as fewer Omicron-specific neutralization antibodies post-vaccination, compared to symptomatic participants. Lower Wuhan and Omicron-specific IgG titres in asymptomatic individuals were also observed pre- and post-vaccination, compared to symptomatic participants. There were no differences in salivary IgA levels. Conventional flow cytometry analysis and multi-dimensional clustering analysis indicated unvaccinated asymptomatic participants had significantly fewer Wuhan-specific IL-2 secreting CD4+ CD45RA+ T cells and activated CD8+ T cells than symptomatic participants, though these differences dissipated after vaccination.<BR><B>CONCLUSIONS: </B>Asymptomatic infection results in decreased antibody and T cell responses to further exposure to SARS-CoV-2 variants, compared to symptomatic infection. Post-vaccination, antibody responses are still inferior, but T cell immunity increases to match symptomatic subjects, emphasising the importance of vaccination to help protect asymptomatic individuals against future variants.