Exposure to one nasal droplet enough for Covid infection – study

Exposure to a single nasal droplet is sufficient to become infected with Covid-19, according to a landmark trial in which healthy volunteers were intentionally given a dose of the virus. The trial, the first to have monitored people during the entire course of infection, also found that people typically develop symptoms very quickly – on average, within two days of encountering the virus – and are most infectious five days into the infection. The study was carried out using a strain of the virus before the emergence of the Alpha, Delta and Omicron variants. The trial’s chief investigator, Prof Christopher Chiu, of Imperial College London, said: “Our study reveals some very interesting clinical insights, particularly around the short incubation period of the virus, extremely high viral shedding from the nose, as well as the utility of lateral flow tests, with potential implications for public health.”