Droplets vs Aerosol spread, COVID19

 

I spoke to a friend who was the Public Health Officer for Sacramento County for many years. She still consults on infectious disease and public health.

There is an important distinction between DROPLET spread and AEROSOL spread.

TB and measles are examples of AEROSOL spread. If someone coughs or sneezes in a room the particles can remain suspended in the air for long periods of time. So if you walk into the room after someone coughs or sneezes you can get the disease. This transmission requires “negative pressure” rooms in a hospital for isolation.

Corona virus and flu are different. They are spread by droplets which do not remain suspended in the air. The infected person must sneeze or cough droplets in your face or you must get the droplets from a contaminated surface (example: door knob) and then touch your face. In hospitals this requires only closing the door of the hospital room, not a negative pressure room (the negative pressure does not allow the aerosol to leave the room and it filters the room air).

The CDC originally issued guidelines for COVID19 that would imply aerosol transmission. But that was not consistent with WHO guidelines and it was not consistent with past recommendations for flu virus and other corona viruses. The rest of the world and the WHO recognized that it was droplet spread, not aerosol spread. The CDC updated its guidelines March 10 to be consistent with WHO and the rest of the world. (SO FAR IT APPEARS THAT COVID19 ACTS LIKE OTHER CORONA VIRUSES AND FLU VIRUSES WHICH ARE DROPLET SPREAD)

CDC recommendations are here

So with COVID19 and the flu, surfaces like doorknobs are important. If someone is sick OR infected but not symptomatic with COVID19, the virus can be transmitted by contact with a surface like a doorknob. These surfaces can be cleaned with Clorox type cleaners which are effective against COVID19, flu, and similar viruses.

Frequent handwashing (at least 20 seconds) and keeping your hands away from your face are important.

Important: PUBLIC HEALTH RECOMMENDATIONS FOR INDIVIDUALS OVER AGE 65 AND THOSE WITH CHRONIC DISEASE INCLUDE VACCINATION FOR PNEUMOCCOUS. Contracting pneumococcal pneumonia before or after COVID19 would be very dangerous.

It is unlikely that there will be an effective COVID19 vaccine for a long time, if ever. Why? Because corona viruses MUTATE QUICKLY (LIKE THE COLD VIRUSES)

Tomorrow I will discuss the need to “flatten the curve” of COVID19 spread, which can minimize the risk that our  health care system will be not be able to care for the very sick. If we do not flatten the curve and instead allow  a high peak of infections, more people will die as a result of infection because not everyone can be treated at once. Our capacity is limited. (The number of ICU beds and ventilators is finite) The concept of “social distancing” will also be discussed.

THIS WEBSITE PROVIDES INFORMATION FOR EDUCATIONAL PURPOSES ONLY. CONSULT YOUR HEALTH CARE PROVIDER FOR MEDICAL ADVICE.

Eat clean, drink filtered water, love, laugh, exercise outdoors in a greenspace, get some morning sunlight, block the blue light before bed, engage in meaningful work, find a sense of purpose, spend time with those you love, AND sleep well tonight.

 Doctor Bob

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