Figure 4.

Monitoring of SARS-CoV-2 specific immune response in patients depending on hospital length of stay. Sixteen convalescent critically ill COVID-19 patients were sampled twice at follow-up visits (i.e. after 9 (M9, n = 16, orange symbols and boxes) and 13 months after hospital discharge (M13; n = 15, red symbols and boxes) and stratified according to length of hospital stay. Results obtained in patients with length of hospital stay inferior to 30 days (n = 7 patients, short, symbols = circles) and in patients with length of hospital stay superior to 30 days (n = 9 patients, Long, symbols = squares) are shown. Fifteen healthy donors either non-infected and non-vaccinated (HV, n = 4, light grey symbols), or after full vaccination (Vacc, n = 4, dark grey symbols and boxes) or after resolution of a non-severe SARS-CoV-2 infection (Inf, n = 7, black symbols and boxes) were concomitantly included. The percentages of T lymphocytes that had proliferated in response to 3 SARS-CoV-2 antigens (Nucleocapsid – Panel a, Membrane – Panel b, Spike –Panel c, expressed as percentages of proliferating T cells among total T cells) and the plasmatic concentrations of anti-SARS-CoV-2 IgG (IgG index – Panel d) were monitored. Results in vaccinated patients are identified by an arrow. Results are presented as individual values and as Tukey Box-plots. Comparison between the two groups of patients at each time point were performed using non parametric Mann Whitney test. * p < 0.05 ** p < 0.01.