Background
The author - whose professional affiliation is the Academic Unit of Respiratory Medicine, University College London, Royal Free and University College Medical School - notes that "in temperate regions, respiratory disease adds greatly to the workload in general practice facilities and hospitals during the winter," partly because of increases in cases of "bronchiolitis in young children caused by infection with respiratory syncytial virus (RSV)."

What was done
Using weekly data on laboratory reports of RSV isolation by the Health Protection Agency and National Health Service hospital laboratories in England and Wales for 1981-2004, along with meteorological data from four surface stations (Ringway, Squires Gate, Malvern and Rothamsted) that "are representative of a roughly triangular area of the United Kingdom enclosed by Preston, London, and Bristol," Donaldson studied the effect of annual mean daily air temperature on the length of the yearly RSV season.

What was learned
Noting that "climate change may be shortening the RSV season," Donaldson found that "the seasons associated with laboratory isolation of respiratory syncytial virus (for 1981-2004) and RSV-related emergency department admissions (for 1990-2004) ended 3.1 and 2.5 weeks earlier, respectively, per 1°C increase in annual central England temperature (P = 0.002 and 0.043, respectively)." Consequently, since "no relationship was observed between the start of each season and temperature," he reports that "the RSV season has become shorter."

What it means
The implications of Donaldson's results are rather obvious. As he describes them, "these findings imply a health benefit of global warming in England and Wales associated with a reduction in the duration of the RSV season and its consequent impact on the health service."