As the Covid-19 pandemic continues to spread around the world, testing remains the most important way to monitor its reach. Testing provides necessary information for countries to act on in order to slow and reduce the spread and impact of Covid-19. This begs the question: Are countries testing enough to monitor their outbreaks?
One metric to gauge the spread of Covid-19 is the percentage of positive test results that are being returned. It is important to note that this differs from a country’s number of positive cases, as the positive test percentage takes into account the total number of tests performed, which also reflects the total number of tests that return a negative test result. This allows for a better understanding of the severity of the spread.
Countries where Covid-19 is currently widespread include Mexico, Argentina, Bolivia, Colombia, and South Africa, where percentages of positive tests range from 24–80%. For example, in Mexico, eight out of ten tests performed for Covid-19 are returning with a positive test result. Countries exhibiting very low levels of Covid-19 include New Zealand, Canada, Australia, the UK, and Germany, with percentages of positive test results ranging from 0.1–1%. For example, in the UK, out of 1,000 tests performed for Covid-19, only five tests return a positive result.
It should be noted that countries with a very high positive test rate are unlikely to be testing widely enough to find all cases. The WHO has suggested a positive test rate of around 3–12% as a general benchmark of adequate testing.