Youth test positivity rate five times higher than seniors'The first study, published today on the Imperial College London preprint server, involved testing a random sample of people from across England for COVID-19 as part of the ongoing Real-Time Assessment of Community Transmission (React 1) study.The researchers showed that COVID-19 infections in England surged from May 20 to Jun 7, with a doubling time of 11 days and an estimated R (reproductive) number of 1.44.  Doubling time is the number of days before coronavirus cases, hospitalizations, or deaths doubled, and R indicates how many people, on average, catch the virus from an infected person.In total, 135 of 108,911 swabs tested positive for COVID-19, for a weighted prevalence of 0.15%, up from 0.10% of swabs collected from Apr 15 to May 3. Northwest England had the highest prevalence (0.26%), while the country's southwest region had the lowest (0.05%). Residents of socioeconomically disadvantaged areas were at nearly double the risk of testing positive, compared with those in less-deprived areas.Young people are behind the surge, with a 5-fold higher rate of COVID-19 test positivity among children 5 to 12 years (0.35% prevalence) and adults 18 to 24 (0.36% prevalence) than in those 65 or older. People younger than 50 were 2.5 times more likely to be infected than older people (prevalence, 0.20% vs 0.08%), although the researchers noted that infections seem to be growing at a comparable rate in both age-groups.