Since the first COVID "long haulers" were reported in 2020, millions of people have experienced long COVID.
While long COVID has no strict definition, it's generally used to describe an illness following a SARS-CoV-2 infection with symptoms that last at least two to three months.
It can manifest as a whole suite of symptoms ranging from body aches and pains to brain fog, and these can substantially vary between people, says Lou Irving, respiratory physician and head of the Royal Melbourne Hospital's post-COVID clinic.