Beforehand, the authors believed a 20 per cent reduction in absences due to illness would be important enough to merit schools considering making hand sanitiser available, so designed the study to detect such a difference.
"Some previous studies suggested that there could be a bigger effect than that, but we wanted to be sure of detecting an effect of that size if it was there," Dr Priest told the Herald.
"We thought that this intervention might help schools reduce the rate of children's absence due to illness, and so this wasn't the finding we had hypothesised."
However, Dr Priest emphasises that the study's findings were not relevant to the importance of hand hygiene in general, nor did it change the message of cleaning hands before eating or after using the toilet, coughing or touching pets.
While the findings suggested that providing hand sanitiser in classrooms may not be an effective way to reduce child-to-child transmission of infectious diseases in high income countries, there were some limitations to the study.
For example, the trial was undertaken during an influenza epidemic, and therefore influenza-related public-health messages about good hand hygiene may have increased hand hygiene among all the children in the study and obscured any effectiveness of the intervention.