"A more targeted screening is necessary", researchers say

Mass screening for corona will not allow for reopening of society

To limit the social and economic costs of the lockdown measures, it was recently proposed that from March 2021 onwards, each Dutch person would be able to have themselves tested once a month on average, even if they are asymptomatic. However, that strategy does not appear to be a feasible solution for the reopening of society. This conclusion is drawn in a new modeling study by epidemiologists from UMC Utrecht and Utrecht University, including mathematician Martin Bootsma.

Research leader Marc Bonten (UMC Utrecht) interprets the results of the modelling study as follows: “Regular mass screening, followed by isolation of infectious persons does not seem a realistic strategy to fully reopen society after the current corona wave. A more targeted screening will therefore be necessary in order to be able to use these rapid tests in a meaningful way as a supplement to other control measures. For example, we can think of mass screening in parts of the country where the infection level is high or in sub-populations where virus spread is high.”

Not feasible

Assuming a natural reproduction number (R0) of 2.5 (meaning that without measures, each infected individual will on average infect 2.5 people), this study shows that the complete elimination of control measures for tested subjects with a negative test result would require that the full population should have a rapid test more often than every three days to keep the R0 below 1. If social distancing measures are maintained, 60 percent of the population would still have to have themselves tested every week to prevent the spread of the corona virus from getting out of hand.

Mathematical model

The researchers developed a mathematical model to investigate if mass testing of the population, including people without symptoms, can stop the spread of the coronavirus. The idea behind this is that massive and regular screening can also identify and isolate asymptomatic spreaders of the virus.

In developing their model, they used variables such as R0, test sensitivity, test frequency, virus spread after a false negative test, virus spread by individuals who do not get tested, the effectiveness of self-isolation after a positive test and the proportion of the population that is tested. They then calculated the required test interval and coverage to keep R0 below 1 during repeated mass screening.

More information
News article by UMC Utrecht