Sometimes professionals use words in very specific ways that aren’t obvious. Just the other day I realized that is what happened with those two words. My Facebook friends have seen me very carefully point out articles like these, which suggest than COVID-19 is airborne, rather than droplet. I did this carefully because before yesterday, the WHO and CDC staunchly denied any such thing and today the WHO merely confirms that there is “emerging evidence.” Today I want to explain why it’s different, and a really big deal, in fairly simple terms.
I work in a hospital, as an Infection Preventionist. Just as the name suggests, I help keep people from getting sicker in the hospital. We used to be called “Infection Control Nurses,” and it’s a tradition that literally goes all the way back to Florence Nightingale. Hospitals use different kinds of precautions — safety measures — to prevent the spread of disease. These measures are based on how the disease itself can move from person to person.
Standard precautions are what we do to protect everybody at all times. This includes keeping your hands clean, using disposable gloves, and changing those gloves between patients. Hand washing is still the most important thing you can do to keep from getting or transmitting any disease. It’s so important the CDC has an entire section on it.
When we know a person has certain infections that could spread, we use Contact precautions. This is for fairly heavy organisms that can survive for a while on surfaces, and that we can inadvertently transport to a new victim on our hands or clothing. One such organism you may have heard of is MRSA, Methicillin Resistant Staphlycoccus Aureus. We also use Contact for more mundane bugs like head lice. For Contact, we make sure to use gloves, treatment gowns to cover our clothing, and we are extra sure to wash our hands after taking our gear off.
Now for the meat of this discussion. Droplet precautions are for organisms that can move in droplets we create when we talk, cough, or sneeze. These droplets can go maybe 6 feet or so (that’s where the 6 feet apart for social distancing comes from) before they go SPLUT! onto a surface. Droplet precautions always includes Contact precautions. That surface can be somebody else’s face, which is why the protective gear for Droplet precautions includes a facemask and ideally eye protection, in addition to gloves and gown. The most common organism for which we use Droplet is the Flu. Remember, up until yesterday, the WHO insisted this was all we needed to protect ourselves from COVID-19. And as of this moment — subject to change without notice — the CDC still does.
By contrast, Airborne precautions are for organisms that can float in the air a long ways and a long time. Much farther than 6 feet. And to do this, they are very small and very lightweight. Examples include Measles, Tuberculosis, and Ebola. These bugs are small enough to get through and around normal surgical masks. These patients should be cared for in a special “negative pressure” hospital room — the HVAC system is designed to create lower air pressure than in surrounding areas while still having fresh air move in and out, so germs aren’t likely to go into the rest of the hospital. To care for these patients, you need special masks, such as N95 or a powered respirator, and they need to fit correctly to prevent germs getting around the edges. That’s over any above gloves, gown, shoe covers, hair covers, and eye/face protection.
As you can see, there’s actually a huge difference between droplet and airborne transmission. And although many experts have privately held that COVID-19 is airborne, its a huge step for the WHO to admit that. I hope the CDC joins them shortly.