Before Daniela Alves caught COVID-19 in March, the 31-year-old Londoner regularly worked overtime to accelerate her career as a mobile app designer. Now, she struggles with client meetings, and says persistent fatigue has halved her productivity.

¡°I was a beast before, but now things are different,¡± Alves says over Zoom, pausing frequently to catch her breath or cough. ¡°I can¡¯t physically do it, and I¡¯m approaching life differently.¡±

Alves said she needed three months off work even after experiencing a ¡°mild¡± infection that didn¡¯t require hospitalization. COVID-19¡¯s lingering effects count her among an expanding population of so-called long-haulers ¡ª survivors left with debilitating conditions who represent another insidious dimension of the pandemic.