As the COVID-19 pandemic enters its third year, researchers are learning more about the long-term effects of the infection and about a collection of symptoms and complications commonly called long COVID. Shortness of breath, fatigue and “brain fog” are among the most common symptoms of long COVID. For some, these symptoms persist after getting infected with coronavirus. For others, new complications arise weeks or months later. There are many unanswered questions, like how common long COVID is, who is more likely to get it and why. And there’s still no consensus in the medical community over the definition, diagnosis and treatment of long COVID. “I think we’re still scratching the surface,” says Dr. Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security, whose research focuses on emerging infectious disease, pandemic preparedness and biosecurity. Below we have addressed some of the key questions about long COVID and …