WHO: Virus transmission airborne, not limited to droplets

Editor's Note

In a move one expert calls “a complete U-turn,” the World Health Organization (WHO) has concluded that viruses transmit through primarily the air via inhalation of tiny suspended particles of saliva and mucus, KFF Health News reported on May 1. Until now, health authorities have relied on the notion that the primary route of transmission is via droplets transmitted from surfaces (via the fingers) or by landing directly in the eyes, nose, or mouth.

According to the report, “traditional beliefs on droplet transmission help explain why the WHO and the CDC focused so acutely on hand-washing and surface-cleaning at the beginning of the pandemic. Such advice overwhelmed recommendations for N95 masks that filter out most virus-laden particles suspended in the air.”  The change emphasizes the importance of improving indoor ventilation and ensuring sufficient stockpiles of quality facemasks to mitigate the effects of airborne diseases, including current threats of measles and H5N1 bird flu.

However, The Centers for Disease Control and Prevention (CDC) “appears poised to brush aside the updated science” in draft guidelines for healthcare facilities, according to the report. In contrast to WHO, CDC distinguishes between short and long distances, recommending looser-fitting masks that block fewer particles than N95s for the former.

The full report provides additional context on differences between the CDC and WHO, as well as costs and other barriers to following the updated science.