Awaking to find that you have a cough or runny nose over the last two and a half years, it’s been sensible to assume that SARS-CoV-2 may have caught up with you. However, for many people, both rapid antigen and PCR tests will have stubbornly refused to return a positive result for SARS-CoV-2. Fantastic that you didn’t have COVID-19, but what did you have that left you feeling unwell?
While diagnostic tests are generally used to determine the infecting agent for severe illnesses that require hospitalization, in reality, for most cases with cold and flu symptoms, the virus responsible is never identified. Indeed, despite many decades of research on respiratory viruses, we still have a surprisingly shallow understanding of which viruses are circulating in a community at a given time, when and where they transmit from person to person, why the symptoms they cause are severe in some but mild in others, or how they evolve over time.