Improving the care of people affected by post-COVID syndrome (LCovB):study protocol of a mixed-methods study - Jennifer Marie Burchardi; Martin Brünger; Helma Freitag; Anna Brock; Carmen Scheibenbogen; Natalie Kohzer; Ellen Kexel; Raphael Kohl; Lea Rückgauer; Eva Schmitz; Andrea Budnick; Johanna Schuster (PLoS ONE, 2026)