When it comes to preventing viral infections — especially those that spread via droplets from coughs and sneezes — washing the hands is always the first-line measure. Now, in the midst of the recent coronavirus outbreak, correctly washing the hands remains public health officials’ top advice when it comes to controlling infection rates.
In their guidelines on how to prevent infection with the novel coronavirus, the World Health Organization (WHO) state that people should “[w]ash [their] hands frequently with soap and water.” Still, people continue to express doubt that something as simple as basic personal hygiene could have any effect in the context of an epidemic.
New research from the Massachusetts Institute of Technology in Cambridge aims to put those doubts to rest by showing just how important washing the hands can be in slowing down the spread of infectious disease. The study, which now appears in the journal Risk Analysis, used epidemiological modeling and data-based simulations to determine if and how better personal hygiene might affect the rate of disease transmission.
30% of people do not wash their hands
The researchers started from existing data indicating that a large number of people do not wash their hands after using the restroom. According to study co-author Prof. Christos Nicolaides,
“70% of […] people who go to the toilet wash their hands afterward. The other 30% don’t [wash their hands]. And of those that do, only 50% do it right.”
The Centers for Disease Control and Prevention (CDC) say that best practices for hand washing include not only rinsing the hands with water, but also applying soap and scrubbing the palms, the back of the hands, between the fingers, and under the fingernails. A person should scrub for at least 20 seconds before rinsing the soap and drying the hands with a clean towel.
However, Prof. Nicolaides notes that of the people who do wash their hands after using the restroom, many never apply soap and spend under 15 seconds on the procedure. “We consider that, at most, 1 in 5 people in an airport have cleaned [their] hands at any given moment in time (i.e., 20% of airport population),” the researchers write in their study paper. The researchers used existing data about global flights. Specifically, they looked at flight duration, flight distance, connections, and estimates of the amount of time travelers spend in airports.
Based on these measures and data from studies into how people interact with others and with their surroundings — as well as what this might mean for the potential of coming into contact with pathogens — the investigators built simulations of contagion patterns. They pinpointed 120 airports that they think play a key role in the spread of contagious agents. However, they also explain that these are not necessarily the airports with the highest traffic.
For example, airports in Tokyo, Japan, and Honolulu, Hawaii, are likely to be key players in the spread of disease due to the fact that they offer direct connections to many of the world’s largest airports. However, these do not have the highest traffic overall. These airports are also points of transit between a significant number of countries in both the Eastern and Western hemispheres. Taken together, these factors make such airports key players in the spread of contagious diseases.
However, the researchers argue that if more people were to wash their hands frequently and correctly, it would significantly slow down the rate at which diseases are likely to spread.
Specifically, if 60% rather than 20% of air travelers maintained clean hands, it could slow down the spread of infections by almost 70%, according to the researchers.