The expression of the fog of war attributed to Carl von Clausewitz in his treatise on military strategy Of the war refers to the uncertainty cloud related to lack of information. The military does not fully understand the threat of the enemy and its ability to fight it. Actions must to a certain extent be planned with a certain shadow area which, like the effect of a fog, gives things exaggerated and unnatural dimensions.
When the SARS-CoV-2 virus first appeared on radar, a thick fog surrounded the COVID-19 disease. In just a few months, the coronavirus had spread like wildfire across the planet, leaving countries to fight a dreaded infection that was causing atypical pneumonia in many.
Many experts agreed with the consensus at the time that viral particles were spread by droplets when people breathed, spoke, coughed and sneezed. And that these droplets fell to the ground for a certain distance. This leads to the two-meter physical distance rule. Nevertheless, not all scientists agreed with this premise. While large droplets can fall to the ground, smaller aerosols containing the virus can travel long distances for longer, like second-hand smoke.
Linsey Marr, an environmental engineer at Virginia Tech, said in an interview that before COVID-19, scientists had difficulty collecting living viruses in the air and measuring what was left in the air. For Marr, the smoking gun is the study where researchers were able to isolate the virus in the air of a hospital room at distances of 2.1 to 4.8 meters, breaking the myth of the two-meter safe. .
With the numerous events of superpropagation and transmission via asymptomatic people, it has become evident that the virus is not transmitted only by droplets, but also by aerosols which remain suspended in confined spaces with little ventilation.
Breaking the siege
In normal times, patients infected with any pathogen are treated in specialized wings for contagious infections. Proper personal protective equipment helps limit the spread of COVID-19 inside hospital walls. And individual rooms with proper ventilation prevent the build-up of the virus and its transmission.
However, the number of hospital patients with COVID-19 has completely overloaded the capacity of some isolation units. During the pandemic, many healthcare workers contracted the virus and patients were infected while in hospital.
The very large amount of hospitalizations of people with COVID-19 has led hospital administrations to redevelop units to treat patients.
To reduce the risk of transmission of the virus in hospital wards, researchers at the University of Cambridge conducted research on the presence of aerosols in certain care units. The team wanted to know if simple portable air filtration units using HEPA 13 filters and UV light were able to reduce airborne transmission of the coronavirus.
To do this, two rooms of the hospital were requisitioned. A first room has been redesigned to accommodate patients with COVID-19 and a second room for intensive care for patients who may or may not need invasive respiratory support. The machines were placed in fixed positions and turned on continuously filtering the volume of air in each room 5 to 10 times per hour.
In the COVID-19 room, before the filter was activated, the researchers were able to collect samples of the virus without any problem. But as soon as the air filter was on, the team were unable to find samples of the virus during the device’s five days of operation.
When the filter was stopped, the air quality had almost returned to the starting condition.
In the other intensive care unit, researchers were surprised to find little coronavirus in the air at the start of the experiment. Some speculate that, despite their poor condition, the patients were at a stage of infection where they were exhaling less virus.
The study has limitations and further similar research would be desirable. However, it is already demonstrating the importance of improving ventilation so that wards are safer for hospitalized patients.
The lessons of Florence
In the XIXe century, Britain was regularly plagued by epidemics, and death rates in hospitals were very high. It took someone like nurse Florence Nightingale to change that. Florence Nightingale witnessed the military hospitals where many soldiers wounded in combat during the Crimean War were crammed. Soldiers who died not from their wounds, but from the infections they had contracted in these highly contaminated places.
On Nightingale’s recommendation, hospitals were to pay more attention to sanitary conditions, ventilation and air flow.
Pavilions designed with windows that had to remain open at all times to promote air circulation. Of course, not all pathogens are spread via aerosols, but in the XIXe century, this strategy to dispel the fog made sense.
As Joseph G. Allen, professor in the School of Public Health at Harvard University, mentions in a text by Washington post, a lot of things should be done to improve indoor air quality. Initiatives combining the ventilation of outdoor air and the recirculation of filtered air.
By improving the air indoors, we reduce the risk of coronavirus infection in hospitals, we make workplaces a little more secure and we get closer to a return to normalcy.
My little finger told me that Florence Nightingale would remind us.