As people begin to emerge from house arrest, there’s much fear about a resurgence of cases of COVID-19. People wonder how to protect themselves, and some are going to a lot of trouble to disinfect packages and groceries. Here are some facts:
- This is a respiratory virus. It gets into your body through the airway, or from your eyes as tears flush it into your nose.
- People generate aerosols by speaking or breathing, not just by coughing or sneezing.
- Viral particles are much smaller than the holes in your mask, which only filters out the larger particles the virus may be riding on.
- SARS-CoV-2 can be recovered from the air for hours and from surfaces for days. There is no evidence of transmission through skin, but if you touch a contaminated object and then your face, you might you might infect or possibly inoculate yourself yourself. There is evidence that frequent handwashing reduces influenza transmission.
- Although SARS-CoV-2 is not known to be transmitted in food, once in your blood it can attack the GI tract—many patients have digestive symptoms. It can be recovered from feces.
- SARS-CoV-2 seems to be most transmissible at the onset of symptoms, but transmission may occur, perhaps in 25 percent of cases, before symptoms are noticed.
- Viruses are bundles of complex chemicals, which must be configured or folded just right to do any damage. They immediately begin to deteriorate in the environment, at a rate determined by temperature, humidity, and other factors, and are destroyed by ultraviolet light, soap, and many chemicals.
These are some sources of known or suspected outbreaks:
- At choir practice, 40 of 60 choir members got infected. Singing is a great aerosol generator.
- At an exclusive meeting of executives in a small closed room in December, attended by a person who had recently traveled to China, everyone got sick, and one transmitted the illness to his girlfriend. Coronavirus was not considered at that time.
- During the 2004 SARS coronavirus epidemic in Hong Kong, more than 300 people in an apartment building apparently got infected from an aerosol generated by a toilet flush, which entered the shared ventilation system.