COVID-19: What to Know About Transmission and Prevention
COVID-19, caused by the RNA retrovirus, SARS-CoV-2, is a highly contagious pathogen affecting both humans and animals. Retro viruses also include the HIV virus, SARS-1 (Bird Flu), SARS-2 (CoVid 19) and MERS (Middle East Respiratory Syndrome). The SARS-2 / CoVid 19 virus is by far the most contagious. To date, there are no successful vaccines for any retrovirus, making prevention and treatment the most viable options to mitigate the devastating effects of an outbreak.
The most common symptoms of COVID-19 are fever, fatigue, and a dry cough. However, many people that have contracted the virus may not experience any symptoms at all.
It is important to understand how COVID-19 is transmitted from one person to another in order to implement the best practices for it’s prevention.
The Current Understanding of COVID-19 Transmission
The Centers of Disease Control and Prevention (CDC) has indicated that the virus can spread in the following ways:
- Between two people who are within 6 feet of each other
- By respiratory droplets produced when an infected person coughs, sneezes, or talks
- When these droplets come in contact with the mouth or nose of a nearby person
Many doctors suspect that the most common way people contract COVID-19 is by touching a surface that has been contaminated by infected droplets and then touching their mouth, nose, or eyes.
It has been observed that COVID-19 can remain on certain surfaces for anywhere from a few hours to several days. This timeline depends on different conditions such as the type of surface as well as temperature and humidity levels.
Does Talking Lead to the Spread of COVID-19?
A new study published by the New England Journal of Medicine and led by scientists at the National Institutes of Health has indicated that speaking at a normal volume produces tiny liquid droplets that can remain suspended in the air and enter the airways of other people, potentially exposing them to viruses such as COVID-19.
Matthew Meselson, a Harvard University biologist, wrote that:
“Aerosols from infected persons may therefore pose an inhalation threat even at considerable distances and in enclosed spaces, particularly if there is poor ventilation. Large particles such as those expelled in a sneeze or cough remain airborne only briefly before settling because of gravity…[but] breathing and talking also produce smaller and much more numerous particles that are too small to settle”.
These droplets are carried by air currents such as those caused by drafts and vents, but also those that are as mild as someone walking around a room.
Previous studies that were unrelated to COVID-19 have found that the droplets emitted during speech are much smaller than those that come from coughing or sneezing. This makes them more likely to remain suspended in the air. However, in still air, a particle with a diameter of 10 microns (roughly one-seventh the width of a human hair) would remain there for approximately 9 minutes.
With aerosols listed as a potential source for COVID-19 infections, Meselson has advised, “wearing a suitable mask whenever it is thought that infected persons may be nearby and of providing adequate ventilation of enclosed spaces where such persons are known to be or may recently have been.”
Unfortunately, determining who is infected and who is not is often impossible to know. A recent study published in Nature Medicine has found that people with COVID-19 infections take two to three days to begin showing symptoms and are most infectious before any symptoms appear.
Asymptomatic Transmission
Symptoms for COVID-19 have varied widely. However, these symptoms have been classified into three categories: typical (fever, cough, loss of smell/ taste, and shortness of breath), atypical, and none.
Among 76 people that participated in a point-prevalence survey, 48 of them (63%) showed positive rRT-PCR results and the remaining 27 people (56%) were essentially asymptomatic. However, symptoms eventually developed in 24 of the participants within an average of 4 days, leading to them being reclassified as presymptomatic.
It should be noted that 17 of the 24 presymptomatic participants (71%) had the virus anywhere from 1-6 days before the development of symptoms.
In conclusion, the report found that more than half of the participants, 27 out of 48, had positive tests and were asymptomatic at testing.
This leads to a re-evaluation in our approach to the prevention of the virus. The transmission from asymptomatic persons and the eventual need to relax current social distancing measures argue for broadened testing to include the prioritization of searching for asymptomatic persons.
The large number of asymptomatic persons that have tested positive for the virus support the use of face masks when in crowded outdoor or indoor spaces.
Protecting Yourself and Others
It is widely agreed that the best way to prevent the illness is to avoid being exposed to the virus.
However, when leaving your home and coming into contact with other people, the following steps are recommended to aid in the prevention of developing the virus:
- Wash your hands often. Using soap or an alcohol-based hand rub, wash your hands for at least 20 seconds and disinfect any surfaces that you may have come into contact with prior to washing your hands.
- Avoid close contact with other people by following social distancing measures and remaining 6 feet away from other individuals at all times.
- Cover your coughs and sneezes with a tissue. Dispose of the tissue immediately and wash your hands following disposal.
There is currently no vaccine available to prevent COVID-19.
This unprecedented pandemic calls for unprecedented measures to be taken if the virus is to be defeated.