Last April, we began to see children admitted to hospital with a new inflammatory disease. Paediatric inflammatory multisystem syndrome temporally associated with Sars-CoV-2 infection (abbreviated to PIMS-TS in the UK or MISC-C in the US) can occur two to six weeks after an initial Covid-19 infection. Many of the children will have been asymptomatic, or have had very mild symptoms, and Covid swabs usually come back negative when they present with PIMS-TS. Antibody tests might show evidence of a recent Covid infection, but hospitals are not routinely testing for Covid antibodies. The symptoms were initially attributed to other inflammatory conditions. News began to come in from other parts of the world, however, confirming that what we were seeing was a novel illness. Cases have been rising again over the last two months.