Air filters don’t stop you catching infectious respiratory diseases, landmark study indicates - The Conversation

What the report says

The Conversation Africa reports that a large UK trial found no evidence that portable Hepa air filters lowered respiratory infection rates in care homes, questioning a pandemic-era assumption that such devices could help control viral spread in communal settings. The study, funded by the National Institute for Health and Care Research, involved 91 care homes for older people: 47 received Hepa filters for shared areas, while 44 did not.

Researchers monitored respiratory infections among residents and staff, as well as staff sickness and absence. According to the article, infection rates were similar in homes with filters and those without them, and there was no measurable difference in staff illness or absenteeism. The study was not blinded, meaning staff and residents knew whether filters were present, but the article notes that this type of design would usually be more likely to make an intervention appear beneficial rather than obscure a real benefit.

The Conversation Africa places the trial in the context of earlier evidence. It says a 2023 review found air-treatment technologies may reduce viruses in air samples, but did not show clear reductions in real-world respiratory or gastrointestinal infections. It also cites studies from Australia, Germany, Switzerland and the United States that did not show consistent infection-control benefits from Hepa filtration in care homes, classrooms or other settings.

The article argues that filters may fail because many respiratory infections are passed at close range before room air can be filtered, and because people move between spaces. It says filtration remains useful in some specialist contexts, such as reducing fungal infection risks for immunocompromised patients, but should not be treated as a proven way to prevent viral respiratory infections in care homes or schools.