An epidemiological investigation on bmj.com discusses the first probable case of human to human transmission of novel avian influenza A (H7N9). The author of the accompanying editorial, James Rudge, from the London School of Hygiene and Tropical Medicine, explains what this means for public health.

Also this week, we know that standardised mortality rates are tricky and have to be interpreted carefully. David Spiegelhater, Winton Professor for the Public Understanding of Risk at the university of Cambridge, explains why a figure of 13 000 excess deaths in NHS hospitals is “number abuse”.

Read the articles:http://www.bmj.com/content/347/bmj.f4730http://www.bmj.com/content/347/bmj.f4893