Propylene glycol inactivates respiratory viruses and prevents airborne transmission

Abstract

Viruses are vulnerable as they transmit between hosts, and we aimed to exploit this critical window. We found that the ubiquitous, safe, inexpensive and biodegradable small molecule propylene glycol (PG) has robust virucidal activity. Propylene glycol rapidly inactivates a broad range of viruses including influenza A, SARS‐CoV‐2 and rotavirus and reduces disease burden in mice when administered intranasally at concentrations commonly found in nasal sprays. Most critically, vaporised PG efficiently abolishes influenza A virus and SARS‐CoV‐2 infectivity within airborne droplets, potently preventing infection at levels well below those tolerated by mammals. We present PG vapour as a first‐in‐class non‐toxic airborne virucide that can prevent transmission of existing and emergent viral pathogens, with clear and immediate implications for public health. image Existing and emerging viruses pose a great threat to the human population. We show the non‐toxic small molecule propylene glycol (PG) rapidly inactivates airborne and surface virus particles, including SARS‐CoV‐2 and influenza A virus (IAV). PG can therefore limit infection transmission. Incubation with PG significantly reduces the infectivity of SARS‐CoV‐2, IAV, Epstein–Barr virus and pseudoviruses expressing a large range of different viral glycoproteins. The magnitude of this broad‐spectrum virucidal activity depends on PG concentration, temperature and incubation time. Hygroscopic PG is attracted into respiratory droplets, so safe levels of PG vapour efficiently prevent airborne virus transmission, reducing SARS‐CoV‐2 and IAV infection > 10,000‐fold within 60 cm of droplet source. In mouse models of infection, inhalation of 20% (v/v) PG solution alongside IAV increases survival and significantly reduces clinical symptoms compared to IAV alone. PG can permeabilise viral lipid envelopes, but it can also directly disrupt viral protein conformations as it additionally inactivates non‐enveloped rotavirus.