The Statistical Society organised an online meeting of statisticians and epidemiologists to discuss the statistical issues concerning how Australia is battling COVID-19. Below are the five recommendations that resulted from the meeting.

HOW CAN STATISTICIANS ASSIST IN THE FIGHT AGAINST COVID-19

IN THE SHORT TERM (i.e. over the next month)

1.        The tests to date have been on a ‘self-selected’ basis. They will not be representative of the population at large and so care needs to be taken on what inferences can be made about the population at large. For example, NSW and Victoria are encouraging testing to anyone who wants it. This will have a bias towards those people who have the time and capacity to drive to a site. Young adults and children are less likely to be tested. The better educated are more likely to be tested. Statisticians could provide advice on how get the best possible population inferences from the active virological (self-selected) testing regime (by geo-demographic reweighting?) and the likely limitations (biases). They could explain what the estimates mean (e.g. possible upper bound rather than actual ratio of infected persons). The extent of advice depends on the amount of geo-demographic information that is associated with individual test results.

2.     At first glance, the self-selected sample might seem to produce an upward bias because people who are symptomatic are more likely to be tested. However, it is also likely that the self-selected sample will under-represent children and young adults especially males. These may be more likely to be asymptomatic or mildly symptomatic although not tested and, if so, this would provide a bias in the opposite direction. Statisticians could provide advice on how to best supplement the active testing sample with populations that will be under-represented.

3.      Statisticians could review procedures for estimating R₀ (the basic reproduction number). This is a crucial statistic for future planning but the statistical science behind it might be able to be improved (Methodology available on the Doherty web site). Also, there are a number of assumptions in the calculations such as all asymptomatic cases actually being pre-symptomatic. It would be importance to know the extent of uncertainty created by these assumptions through tools such as sensitivity analysis.

IN THE MEDIUM TERM (Until the virus is under control but should start work in the short term)

4.     As soon as feasible, a national survey be conducted jointly by the ABS and health authorities to estimate the number of infections after restrictions start being released. This information is very important for monitoring the potential for a second wave that is difficult to contain. It is may become more important in the winter months when there will be more overlap between COVID-19 symptoms and other winter ailments. Also, the number of asymptotic infections is unknown. International studies show the percentage is much higher than what health experts believe is the case in Australia. Statisticians might be able to assist the ABS with the analysis of the data. The survey should be repeated until there is confidence the virus is under control.

5.      Assist with the design, calibration and analysis of sewage testing. It could be combined with the national survey in the first instance to provide a ‘calibration experiment’. This would allow calibration with what we see in the population, reducing the need for large scale surveys in the future.

Dennis Trewin