Progressive and parallel decline of humoral and T cell immunity in convalescent health care workers with asymptomatic or mild-moderate SARS-CoV-2 infection.

We investigated the duration of humoral and T-cell immune response in paired samples among 22 convalescent health care workers (HCWs). A median of 1.8 months after diagnosis, T-cell response was significantly lower in HCWs with early loss of antibodies (6 cases, 27%). After 5.1 months, antibodies decline was observed in 77% of cases (41% seroreverted; p<0.01), and 36% have lost T-cell response (75% lost response to spike protein). Persistence of immune response was observed in those who developed a greater adaptative immune response. Our data point to the initial immune response as the relevant player in COVID-19 duration of protection.