June 27, 2020

Test frequency matters more than test sensitivity for stopping outbreaks

By admin

Communities such as universities where COVID-19 cases could quickly spiral out of control should frequently test large numbers of people for the new coronavirus — even if that means using a relatively insensitive test.

Tests that rely on the technique quantitative polymerase chain reaction (qPCR) can detect the merest traces of SARS-CoV-2 genetic material but are expensive and slow to return results. To gauge the importance of test sensitivity, Michael Mina at the Harvard T. H. Chan School of Public Health in Boston, Massachusetts, and his colleagues modelled the effect of widespread testing on viral spread in a large group of people.

The researchers found that weekly surveillance testing, paired with case isolation, would limit an outbreak even if the testing method was less sensitive than qPCR. By contrast, surveillance testing done every 14 days would allow the total number of infections to climb almost as high as if there were no testing at all. The findings have not yet been peer reviewed.

Scientists have created and described more than 3,800 variations of the protein that the new coronavirus uses to latch on to its targets — a feat that reveals which parts of the protein are crucial for binding to human cells.