December 9, 2021

National Academies Report Discusses Non-Vaccine Flu Interventions

Drawing on the experiences of the COVID-19 pandemic, a recent report from the National Academies of Sciences, Engineering, and Medicine analyzes the effectiveness of non-vaccine interventions to counter the spread of influenza. A section on controls in indoor environments covers the efficacy and strength of evidence for use of barriers, ventilation and filtration, ultraviolet inactivation, ionization, and surface cleaning.

According to the report, published research indicates that ventilation and air filtration are moderately effective at reducing transmission of respiratory viruses. The report calls for the development of technical recommendations on ventilation in various settings to reduce transmission and the incorporation of these recommendations into building standards.

The installation of barriers is among the least effective interventions for reducing transmission, useful only in the context of short, face-to-face interactions between two people, the report states. In other scenarios, barriers may actually increase risk of transmission due to their effects on airflow patterns in indoor environments.

Surface cleaning, which was an area of emphasis in public health messaging in the early days of the COVID-19 pandemic, was found to have low efficacy for limiting transmission for SARS-CoV-2 because the virus “seems to be mediated primarily by direct contact, droplets, or airborne transmission,” the report states. However, surface cleaning may be more effective for other pathogens such as influenza virus.

Similarly, the report characterizes ionization as an intervention with low efficacy and notes that devices using this technology may introduce harmful byproducts.

While the strength of evidence supporting the use of ultraviolet germicidal irradiation (UVGI) is low, according to the report, research has demonstrated that this technology is moderately effective at inactivating SARS-CoV-2 on surfaces. The report states that design considerations such as the size of the room and the height at which UVGI fixtures are installed are vital to the success and safety of this intervention. Conditions within rooms may lead to inadvertent “hot spots” that could place room occupants at risk of overexposure to UV.

Other sections of the report address the effectiveness of actions that individuals and governments can take to limit transmission of respiratory viruses. Citing laboratory studies, the report states that strong evidence exists that “properly designed, well-fitting face masks with multiple layers of material and strong filtration capacity” are highly effective at limiting transmission.

“Public Health Lessons for Non-Vaccine Influenza Interventions” is available as a free download from the National Academies website. The report is one of four released last month by the National Academies that apply lessons from the COVID-19 pandemic to preparations for a possible influenza pandemic. In a press release announcing the reports, the National Academies states, “Influenza remains the circulating pathogen most likely to cause a pandemic, and the risk for pandemic influenza may be higher during the COVID-19 era due to changes in global and regional conditions affecting humans, animals, and their contact patterns. Each year, there are 3 million to 5 million cases of influenza globally, and up to 650,000 deaths.”