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How to tackle a respiratory virus?

article on prevention measures for respiratory infections
© COG-Train

In week 1 we discussed that respiratory viruses travel from one individual to another through air. When an infected person sneezes, coughs, eats, sings or even whispers, they release air droplets and aerosols that can carry viruses long distances. The table below compares some of the characteristics of droplets with those of aerosols.

Droplet Aerosol
> 5 μm (may be much larger) < 5 μm
Short range (<2 m) Long range – (up to km)
Short dwell time Long dwell time – need air handling
Resistant to environmental damage Readily dry
Can enter upper airway Can enter lower airway

People who are not protected against a particular airborne virus are susceptible to becoming infected and transmitting the disease to new hosts. Preventive measures for most respiratory infections include vaccinations, use of face covering, ventilation and air circulation, and hand hygiene.

Vaccination: stimulates the immune system to produce antibodies and trigger immune responses against its target when an individual encounters the virus. Not all vaccines prevent infection, but all of them are designed to mitigate severe disease and death.

Face covering: a physical barrier that prevents the spread of infective droplets and aerosols. Their efficiency depends on their filtration capacity. Cloth face coverings, although mitigating the spread of the virus, allow the dissemination of small infective particles, whereas filtering facepiece masks (FFP2 or N95) can filter up to 95% of droplets (Figure 1).

A dot-plot showing the protection of different face coverings from highest to lowest protection: fitted N95, surgical, cotton+polypropylene+cotton, 2 layer polypropylene, swath 2 layer cotton pleated, valved N95, 2 layer cotton Olson style, one layer cotton, knitted, bandana, none, neck gaiter

Figure 1 – Droplet transmission through face masks. Each data point represents the relative droplet count (RDC) compared with no mask. The lower the RDC, the more droplets are blocked by the mask, and increased the filtration efficiency. Source Science Advances.

Ventilation: open windows increase the circulation and renewal of the air in a room. The viral particles in the air are carried outside the room, significantly reducing the number of virus particles in suspension and the spread of the infection.

Hand hygiene: we can touch contaminated surfaces and bring the pathogens to our mouth and nose, where the viruses can infect the mucosa cells. Although this is not the main route of COVID-19 spread, hands washing is a preventive measure for most infectious diseases.

Which mitigations have dominated in your context? What do you think is the best set of preventive measures? Share your thoughts in the comments section

© COG-Train
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