The Nature paper, SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls, states “infection with betacoronaviruses induces multispecific and long-lasting T cell immunity to the structural protein NP.” It also shows that “SARS-recovered patients (n=23) still possess long-lasting memory T cells reactive to SARS-NP 17 years after the 2003 outbreak”
To understand that I needed to lookup what NP or nucleocapsid protein means to Covid-19. “The SARS-CoV-2 genome contains approximately 30 kilobases that encode four structural proteins: spike, envelope, membrane, and nucleocapsid.” NP is that last one.
“The SARS-CoV nucleocapsid protein is integral for viral self-assembly and is involved with regulation of the cell cycle.” So it seams that if you recover from Covid-19 you will be immune for a long time. That is much needed good news.
Sources:
The Polen Report 