Tuesday marks five years since the World Health Organization (WHO) declared the global outbreak of COVID-19 to be a pandemic.

The novel coronavirus that causes COVID-19 has spread globally, killing hundreds of thousands of people and infecting millions more. The pandemic has upended life around the world, delivering a ...

There remains much we don’t know about long covid, including its origins. It’s a complex condition likely caused by more than one thing, including a dysfunctional immune response to the earliest covid ...