Michelle Healy

USA TODAY

Putting alcohol-based hand sanitizers in classrooms in the hopes of reducing school absences due to illness may not be worth the expense in high-income countries where clean water for washing hands is readily available, a study says.

It finds that adding the sanitizers to school-age kids' usual hand hygiene routine — washing with soap and water — did not reduce illness-related absences.

The findings, reported in this week's PLOS Medicine, do not apply to hospitals and health care facilities or in controlling the spread of gastrointestinal illness where hand sanitizers remain a vital component of infection control, says lead study author Patricia Priest of New Zealand's University of Otago, in Dunedin, in an e-mail.

"There are some studies that do show a reduction in school absences due to (some) illnesses with hand sanitizer interventions," she writes. But the research literature "increasingly shows that it is unlikely that interventions that seek to increase hand hygiene over and above what's 'normal' in high-income countries" will reduce person-to-person transmission of respiratory infections, which comprise a high proportion of illnesses causing school absence."

The study looked at 2,443 students, ages 5 to 11, in 68 schools in New Zealand. They each received a 30-minute in-class hand hygiene education lesson that reinforced knowledge about "germs causing sickness, and the need to wash hands well with soap and water after using the toilet, before eating, after touching pets, etc.," says Priest, a public health physician and infectious disease epidemiologist at the university's Dunedin School of Medicine.

In half of the schools, dispensers containing alcohol-based hand sanitizer were installed in classrooms over two winter terms, and students were asked to use them after coughing or sneezing and on the way out of the classroom for morning recess or lunch. The remaining schools served as a control, receiving only the hand hygiene lesson. Parents and caregivers were contacted to explain the reason for any absence.

Researchers found that the rate of absences due to illness was similar in both the intervention schools that received the dispensers and the control schools that washed with soap and water.

In addition, use of a hand sanitizer did not reduce the number of absences due to a specific illness (respiratory or gastrointestinal), the length of illness and length of absence from school, or the number of episodes in which at least one other family member became ill. When using school attendance records from all children in the participating schools, the number of absences for any reason and length of absence did not differ between the intervention and control schools.

The study notes that because it was conducted during the 2009 swine flu pandemic, widespread public health messages from government agencies about hand hygiene, along with other influenza-prevention actions such as covering coughs and sneezes, "may have increased hand hygiene among all children" and obscured any effectiveness of the hand sanitizer intervention.

"Personally, I am not convinced that the extra exhortation to wash hands would have had a major, sustained, impact on primary-school children's hand hygiene practice over 20 weeks, but it has to be considered as a possibility," Priest says.

The study's findings are not very surprising, says Allison Aiello, an epidemiologist at the University of North Carolina's Gillings School of Global Public Health, in an e-mail. She was not involved in the new research.

It is very difficult to identify "an incremental effect" of hand sanitizer against a setting of relatively high rates of hand hygiene, low overall risk of illness in the population and during respiratory illness transmission such as a pandemic, Aiello says, "because both direct and indirect transmission routes likely play a role in transmission."

She adds that alcohol-based sanitizers have shown a large benefit in terms of reductions in infections in hospital settings and have not been associated with antibiotic resistance, as has been reported with triclosan-containing antibacterial soaps.