London, Jan 21 : Mild symptoms, poor knowledge of nearby testing sites, and certain demographic factors have been identified as barriers to Covid-19 testing, claims a new study. According to a new study of more than 4 million adults in the UK, published in the journal PLOS Global Public Health, these findings have international public health implications, too. "Knowing when and where to get a test is crucial to curbing Covid-19 transmission, yet one in four people with the UK test-qualifying symptoms of fever, cough, or loss of smell did not get tested," said the authors, including Christina M. Astley of Boston Children's Hospital, US, and colleagues from King's College London. "Over a third of these individuals did not recognise the three symptoms that would qualify them for a test, and about a third of those who wanted testing did not know where to go, indicating that more effective education is needed to close the testing gap," they added. Testing is a crucial component of the Covid-19 public health response, even as countries roll out vaccination campaigns. In the UK, free PCR Covid-19 tests are offered to people with any of three symptoms -- a high temperature, a new, continuous cough, or a change in their sense of smell or taste. However, more than a quarter of people in the UK reporting these symptoms don't get tested. In the new study, the team analysed data on 4.3 million people enrolled in the UK Zoe Covid Symptom Study, who use a smartphone app to self-report Covid symptoms and test results. They sent follow-up surveys at the end of 2020 to nearly 5,000 people who reported Covid-19 symptoms but no test. The researchers also studied more than 700,000 responses, received between April 2020 and February 2021, from UK participants of the University of Maryland Global Covid-19 Trends and Impact Survey (UMD-CTIS), an ongoing survey partially carried out on Facebook. The proportion of Zoe participants reporting Covid-19 testing among those reporting symptoms has increased over time, the study found, from less than 20 per cent in April 2020 to more than 70 per cent in January 2021. The odds of a symptomatic person not testing were higher for those with just one symptom compared to more symptoms (27.1 per cent versus 14.6 per cent), and for those with symptoms lasting two or fewer days compared to those with longer-lasting symptoms (30.1 per cent vs 14.6 per cent). /IANS