by Tia Will
The following is a summary of recent information on the transmissibility of the coronavirus and my current thoughts on how best to protect ourselves, both on the individual and community level from viral spread.
Primary means of respiratory viral spread:
- Sneeze –“The largest droplets rapidly settle within 1 to 2 m away from the person. The smaller and evaporating droplets are trapped in a turbulent puff cloud, remain suspended, and, over the course of seconds to a few minutes, can travel the dimensions of a room and land up to 6 to 8 m away.” – New England Journal of Medicine
- Cough – believed to spread droplets up to six meters
- Loud talking/ singing – forceful exhalation of air as in shouting, loud speech, singing tends to send smaller aerosolized particles further than 6 ft – exact distance unknown
- Surface transfer – demonstrated to be significant in studies assessing transfer of substances meant to mimic droplets on objects such as shared serving instruments at buffets, cutlery, napkins, table cloths, door knobs, light switches with implications for subsequent transfer to one’s face. However, this transfer seems to require a significant amount of virus on the surface and is felt to be very unlikely from home deliveries, food packaging and items purchased from grocery stores.
Other important factors:
- Time – brief encounters carry less risk. Encounters such as walking past another person or jogging are not even considered significant encounters by many researchers. Being even socially distanced for extended periods of an hour or more is considered significant.
- Ambient conditions – outside with appropriate distancing is safest due to dispersal of particles by air circulation and distance.
- Enclosed spaces with poor ventilation such as small bars/restaurants/airplane cabins/cruise ships are likely to represent increased risk.
Means of protection:
- Vaccine – not yet available for this coronavirus
- Specific medications either preventative or curative– not yet available
- Isolation – critical for those who are either culture-positive or who have strong clinical indication of COVID-19. A good idea for those at high risk of a serious course of the disease, early thought to only include seniors and those with significant medical problems or undergoing treatment which could affect the immune system. However, more recent information suggests that as many as 20% of individuals hospitalized have been under 50 and approximately 12 % of those have required ICU care. Also, of concern although still rare is the presence of a Kawasaki-like inflammatory disease which has been found in association with coronavirus positivity in children under the age of 16.
- Social distancing – the practice of maintaining a protective distance, usually defined here as 6 feet apart based on early droplet studies.
- Hand washing with soap – useful for removal of virus thus preventing transfer from high-touch surfaces to one’s face or other surfaces.
- Face coverings
Those who have read my previous articles know that while I initially thought face covering was a good idea, I also believed there was not enough evidence to support mandatory face coverings outside a medical setting. Three circumstances have changed my mind.
- The existence of asymptomatic spread. Unlike colds and the seasonal flu, the novel coronavirus is unique in having been demonstrated to have significant asymptomatic spread, meaning that an individual may never show signs of infection and still transfer the virus by any of the above means.
- Pre-symptomatic spread. This is the ability of an individual who is destined to develop classic COVID-19 symptoms to transfer the virus prior to exhibiting any symptoms.
- The existence of atypical presentations of COVID-19 including abdominal pain, vomiting and diarrhea as presenting symptoms.
- Additional studies supporting the efficacy of near universal use of masking in prevention of community spread.
Types of masks:
- N95 masks – named due to their ability to block passage of 95% of viral particles in previously known respiratory illnesses. Capable of protecting both the wearer and contacts from droplet and aerosolized particles. Must be fitted and tested to be effective.
In our current setting, appropriate only for first responders and medical personnel.
- Surgical masks – Intended to be single use and primarily protect contacts from the wearer although they also serve as a physical barrier of protection for the wearer from bodily fluids of patients. Like N95s, due to current conditions, appropriate for medical personnel.
- Cloth face coverings – while not effective in protection of the wearer, have been shown to decrease risk for individuals encountered by the wearer. Most effective when usage is is between 80-100% of the population, and when enacted early in the outbreak. In addition to articles previously linked by Richard McCann and Robert Canning, a recent article sent to me by David Greenwald: Mask Study has led me to agreement with the following recommendations, mostly from the article, in addition to isolation of high risk groups, social distancing, personal hygiene, testing and tracing.
Additional current recommendations:
- Mandatory masking in high risk settings such as public transportation, shops, areas where social distancing cannot be maintained.
- Mandatory masking for workers in essential services.
- National availability of adequate masking for the entire population in times of pandemic
- Cloth face coverings should be encouraged for nonmedical personnel until such time as PPE becomes readily available for first responders and medical personnel.
- Clear messaging from the government should occur early in an outbreak and convey the reason for face covering as the protection of all members of the community, not just the wearer or those deemed most vulnerable.
- These relatively simple measures: isolation when ill, social distancing, alternatives to hand shaking, increased hand washing and facial covering, if considered the new normal, could prevent the spread of the novel coronavirus, & also prevent transmission of viruses responsible for the common cold, seasonal flu & the next, and inevitable, pandemic.