Moral Directions

This cryptic clue

Right, second right, then a left.  (5)

was set by 'Punk' inThe Independent (a daily UK newspaper), The solution depends on a frequently-used abbreviation of the synonym 'moment' for 'second'.

Covid-19: Who passes it on?

In tracking the course of an epidemic, the R-number - the average number of infections caused by an infectious individual - is a crucial parameter in understanding the spread of a disease. Although less talked about, the dispersion rate is important too. The following cumulative frequency chart, which is taken from a large-scale study of covid-19 track-and-trace data in India, shows that 71% of infected individuals did not pass their infection on to anyone else; a further 19% accounted for 40% of the directly-transmitted infections, while the remaining 10%, the so-called 'superspreaders', were responsible for a full 60% of the transmitted cases.

Small proportion responsible for most infections

The above diagram, published in The Economist, uses data from a paper by Ramanan Laxminarayan of Princeton University and eight co-authors that analyses information from test-and-trace records in Andhra Pradesh & Tamil Nadu between March and August 2020. Their data involved 84,965 infected individuals and 575,071 of their known contacts who subsequently tested positive for covid-19.