The Covid-19 symptomatic ratio
Age-specific likelihood of developing symptoms and of progressing to critical disease after SARS-CoV-2 infection


A new epidemiological study of the Bruno Kessler Foundation of Trento, published on JAMA Network Open, quantified the age- and sex-specific likelihood of developing respiratory symptoms or fever ≥37.5 °C after SARS-CoV-2 infection. The study – the first author of which is Piero Poletti of the Health Emergencies Center of FBK led by Stefano Merler – also provides estimates of the probability of progressing to critical disease, i.e. of requiring admission to an intensive care unit or resulting in death. The innovative contribution of this study is that the authors, estimated probabilities on infections, not on cases, incluing only subjects from clusters of contacts where all individuals were tested against infection, either via RT-PCR or IgG serological screening.