As businesses and activities are re-opening, many people have decided to relax their precautions to avoid infection with COVID-19. If you are a person who is at high risk for complications from this virus, I believe that you should continue to be on guard. You are at increased risk for complications if you have any defect in your immune system: a history of heart attacks or heart disease, cancers, diabetes, auto-immune disease, kidney disease, obesity, high blood pressure, a chronic infection or any other serious illness. People with an existing lung disease (asthma, bronchitis, COPD, emphysema, and so forth) are at high risk for complications.
The vast majority of COVID-19 infections are caused by breathing respiratory droplets indoors. A study from China found that only two of 1245 cases were acquired outdoors (MedRxiv, published online April 7, 2020). The remainder were transmitted in various indoor environments — homes, public transportation, shopping and so forth. Another study from China showed that family members of an infected person are at very high risk for infection (Lancet Infect Dis, May 2020;20(5):534-535). Coughing, sneezing, and talking can spew infected droplets into the air from people who may have no symptoms whatever. The droplets spread usually for 3-6 feet, but some reports have extended the distance as far as 30 feet.
Contaminated Surfaces in a Hospital
Detailed analysis of contamination in hospitals during the COVID-19 epidemic can teach us a lot about how the virus spreads in other indoor spaces. A study reported in Emerging Infectious Diseases (July, 2020;26(7)) found that:
• The virus was widely distributed on floors, computer mice, trash cans, sickbed handrails and other surfaces, and was detected in the air 12 feet from patients.
• The highest concentration of virus was in the intensive care unit.
• Floors of the entire hospital were loaded with virus, because gravity settles the respiratory droplets there.
• Fifty percent of the shoe soles of medical personnel were covered with virus.
• Masks were loaded with virus — a sign that they are working, but need to be washed or discarded after every use.
Try to Avoid Public Restrooms
Restrooms can be a major source of infection, and the highest concentrations of virus in a hospital were found in toilets (Nature, April 27, 2020;582:557–560). The virus can live in stool and aerosol droplets can rise three feet above a toilet when it is flushed (Physics of Fluids, June 15, 2020). If the toilet has a lid, close it before flushing and get away from the toilet immediately after flushing. If you have to use a public restroom:
• Wear a mask.
• Carry a paper towel or tissue and use it to open doors or touch any handles or anything else.
• Flush with your foot if possible.
• Leave as quickly as you can. This is not the place to comb your hair, fix your make-up, chat with friends or anything else.
Rules to Live By (For Now)
• Wear a face mask any time you expect to be around people who are not members of your household. Masks protect others from your secretions, but they do collect virus droplets, so you have to wash your mask after you use it (or use a disposable mask). See Should You Wear a Mask When You Exercise Outdoors?
• Stay at least six feet away from other people.
• Avoid everyone with respiratory symptoms.
• Use 20-second soap hand washes after you touch anything (if you can), and frequently throughout the day.
• Try not to touch your eyes, nose or mouth, the primary sources of viral entry into your body.
• If you feel sick, stay home.
• If you have to travel, try to go by car. If possible, avoid group travel such as trains, planes, buses and boats.
These are times that will pass when we have a vaccine early next year. For now, realize that you can become infected anywhere an infected person has breathed or coughed out the virus. I am using the good news about low rates of infection outdoors to inspire me to spend lots of time riding my bicycle.