6 Feet Apart — How cystic fibrosis research helped establish social distancing rules

As the COVID-19 pandemic continues to challenge our day to day lives, one of the primary causes of disruption has come from the need for social distancing. A term that now causes a stress response in many people around the world, social distancing is better explained as the act of physically distancing oneself from other human beings to prevent the spread of disease.

Because the COVID-19 coronavirus is transmittable through droplets (aka breathing, sneezing, and coughing into the air and onto other people), many health authorities recommend that both healthy and infected people maintain physical distance from others. This is why busy working offices, restaurants, bars, and exercise facilities have been hit the hardest during this time — in many of these locations, social distancing is near impossible to maintain and enforce. And while the partial or complete closure of these spaces has been one of the best ways we have managed to control the spread of COVID-19, these closures have also led to economic losses and increased financial stress.

According to the Center for Disease Control and Prevention (CDC), a minimum of a six-foot buffer exists between any two people to reduce the risk of transmitting COVID-19 (1). But why is it six feet, instead of four or ten? Is there a particular reason why six feet is the chosen distance? The answer lies within the tight-knit (but not closely gathering) community of people living with cystic fibrosis.

As it turns out, a population of patients have been living by social distancing rules long before the emergence of this pandemic. Children and young adults living with a genetic condition called cystic fibrosis (also known as CF for short) must socially distance themselves from each other in order to reduce the risk of transmitting life-threatening bacteria from one patient to another. Thanks to them, we have been able to learn more about disease transmission and the true success rate of simply staying six feet apart from each other.

What is cystic fibrosis?

Cystic fibrosis is a rare genetic condition that primarily impacts the health and function of the respiratory and digestive systems. Typically diagnosed in young children, CF causes the normal mucus found in healthy lung and intestinal tissue to become thick and sticky (2). This becomes particularly dangerous in lung tissues, where build-ups of this thick mucus can lead to difficulty breathing and respiratory distress.

For people living with cystic fibrosis, they experience a plethora of symptoms on a daily basis. Persistent cough, lung infections, shortness of breath, and difficulty maintaining a healthy weight are all common symptoms for CF patients. People living with cystic fibrosis are also always at risk of developing serious and life-threatening lung infections, just from coming into contact with bacteria that many of us carry with us on a daily basis. Because 75% of people with cystic fibrosis are diagnosed with the condition within the first two years of their life, this disease is truly a lifelong battle to maintain healthy lung function (2).

Caused by a mutation in the CFTR gene, cystic fibrosis can be inherited by a child if both parents are carriers for the condition (2). Based on a simple genetic tree, the risk of developing the disease for a child from two CF carrier parents is as follows (3):

• There is a 25% chance that they inherit cystic fibrosis from their parents. This means they will be a carrier for the disease and experience the active disease.

• There is a 50% chance that they will be carriers of the disease, but have no symptoms of the disease. If they have children with another person who is a carrier, their children will be at risk for having CF.

• There is a 25% chance that they will not be a carrier OR have CF, ending the cycle of the disease for their children.

Without knowledge of the condition, many people do not know that they have a family history of cystic fibrosis and could be carriers of the mutation. It is estimated that over 70,000 people live with cystic fibrosis worldwide, with 1,000 cases being added every single year (2).

Treatment for cystic fibrosis is a life-long commitment. Involving extensive care such as physical therapy to loosen and remove mucus, strict medication regimes, and very careful monitoring, it is very common for CF patients to require hospital care to better manage their condition. Because cystic fibrosis is a progressive disease, the severity of symptoms continues to worsen with age and increased damage to the lungs. As a result, almost all CF patients require a full lung transplant at some point in their lifetime to give them a better quality of life. With limited organ donors and incredibly specific matching requirements, this life-extending surgery is not always feasible for many patients, which unfortunately reduces their lifespan.

Why are some germs particularly dangerous for people with CF?

The thick mucus caused by cystic fibrosis is the perfect environment for harmful bacteria to grow and thrive. Because of this, many patients with CF regularly experience lung infections, which triggers the immune system to release white blood cells. Designed to target bacteria to prevent disease spread, the white blood cells in a person with CF cause inflammation in the lungs, which in turn causes the production of increased thick mucus. Thus begins a vicious cycle of infection, inflammation, mucus production, and lung damage, all of which lead to a rapid decline in lung function and health. 

As the disease progresses, the person’s lung capacity and function steadily decline, with the majority of CF patients over the age of 35 living with 40-69% of their lung function (4). This impairment in their lung health has proven to be fatal, with 95% of patients with cystic fibrosis passing away from respiratory failure caused by chronic pulmonary sepsis (systemic infections starting from the lungs) (5).

While many different bacteria are a threat to the health of a person with cystic fibrosis, there are particular microorganisms that pose additional threats to their lung health. Some of the most dangerous bacteria for patients with CF include (6):

• Multi-drug-resistant Pseudomonas aeruginosa (P. aeruginosa) — This common bacteria is, unfortunately, most commonly transmitted from one CF patient to another. It is incredibly hard to treat with modern antibiotics and treatments, which has resulted in about half of all cystic fibrosis patients hosting colonies of this bacteria in their lungs.

• Burkholderia cepacia complex (B. cepacia) — This highly infectious bacteria thrives in wet environments like the thick mucus of patients with CF. It is very difficult to successfully treat this type of infection.

• Methicillin-resistant Staphylococcus aureus (MSRA) — This better-known bacteria has become a household name because of its high infection rate and strong resistance to modern antibiotics. It is passed on through casual contact or by touching unclean surfaces.

• Nontuberculous mycobacteria (NTM) — This bacteria is most commonly found living in soil, water reservoirs, or swamps. Able to withstand extreme environmental conditions, it is very resistant to disinfectants and is often found in the mucus of people with CF.

Where did the 6 foot rule come from?

The journey to establishing the six-foot rule starts back in the 1980s. During this time, many doctors believed that the common P. aeruginosa was one of the only massively infectious bacteria that was causing fatalities in CF patients. But, during a study conducted on the autopsies of patients with cystic fibrosis, it was found that over 80% of them tested positive for another type of bacteria — Burkholderia cepacia (7).

The CDC conducted further research and found that over 18% of patients with CF had B. cepacia, and this infection caused significant lung damage and progression of the disease (7). In addition to this alarmingly high infection rate, 20% of CF patients with B. cepacia had passed away within 90 days of contracting the infection (7). 

These numbers were very frightening for the CF community, as the majority of the patients originally diagnosed with B. cepacia had a higher FEV1 (the amount of air you can force from your lungs in one second) than those without it. So while these patients started in a healthier spot than those commonly diagnosed with P. aeruginosa infections, cystic fibrosis patients with a B. cepacia infection had a very sharp and fast decline in their lung health which greatly contributed to their risk of mortality (5).

Unfortunately, B. cepacia is a hardy bacteria that is very resistant to antibiotics and modern treatments. Because people living with cystic fibrosis are more likely to get infections than the general population, it was very common for CF patients to pass on diseases amongst themselves when they got together in close gatherings. Passed on through handshakes, hugs, and casual contact, it became clear that close contact between CF patients was putting people at serious risk of becoming profoundly ill.

Armed with this new information, the Cystic Fibrosis Foundation released guidelines in 2003 aimed to provide new standards of care for the CF community. In these guidelines, the idea of the six-foot rule was first introduced as a way to encourage social distancing between CF patients. Avoiding direct contact, cleaning shared surfaces, and meeting outdoors in well-ventilated areas were also recommended. Research has shown that six feet (or 2 meters) is generally considered to be the distance that large infectious droplets will spread from person to person after a cough or sneeze — therefore, CF patients with infectious bacteria could still see their other CF friends without risk of infection so long as they maintained at least six feet of distance (7).

Are these guidelines starting to sound familiar? There is a good reason why the CDC borrowed many of the same recommendations used for CF patients at the start of the COVID-19 pandemic — and that’s because they work!

How well did this policy work?

At the onset of these new guidelines, the CF community had a lot of adjustments to make. Popular summer camps were closed, support groups had to be cancelled, and many friends were no longer able to get together in the ways they used to. And while some thought that these changes were too severe, the distancing proved to be incredibly effective in preventing the spread of infections.

When it was first identified in the 1980s, the infection rate of B. cepacia was 18%. But, after a few years of integrating the six-foot rule, the prevalence of B. cepacia infections was down to 2.4% (8). With the majority of person-to-person contact within the CF community now heavily limited, researchers now suspect that all B. cepacia infections come from the environment, rather than from other infected individuals.

Small sacrifices and a willingness to adapt have helped the CF community come out stronger and healthier than ever before — lessons many of us should carry with us as we continue to self-isolate to prevent the spread of the COVID-19 pandemic.

Cystic fibrosis patients now live longer lives

With modern advances in medical treatments and the now fully adopted practices of social and physical distancing, children diagnosed with cystic fibrosis are significantly more likely to live into adulthood. In fact, babies born with CF today are projected to live well into their 40’s and beyond, which is significantly longer than the expected lifespan even a decade or two ago (9).

While CF is still not a curable condition, improvements in quality and duration of life have made disease management a more feasible task. From the identification of the CFTR protein and gene to improved antibiotic medications and lung transplants, people with cystic fibrosis are finally able to start future planning as they are living full and meaningful lives well into adulthood.

So, as many of us grumble and complain about strict COVID-19 social distancing rules in place, it may be time to take a moment to consider where these restrictions come from in the first place. The commitment and persistence of the CF community have led to the discovery of public health policies that genuinely save lives — all thanks to their continued sacrifices. Working together and treating others with compassion, we too can use the six-foot rule to reduce infection rates and create a healthier world for everyone. 

Sources

1. How to protect yourself & others | Centers for Disease Control and Prevention

2. About cystic fibrosis | Cystic Fibrosis Foundation

3. Cystic fibrosis by the numbers: Facts, statistics, and you | Healthline

4. 2019 Patient registry annual data report | Cystic Fibrosis Foundation

5. Outcome of Burkholderia cepacia colonisation in an adult cystic fibrosis centre (2002)

6. Germs and cystic fibrosis: The facts | Cystic Fibrosis Foundation

7. How cystic fibrosis research helped establish the 6-foot rule for physical distancing | bioMerieux Connection

8. The case for social distancing: Lessons from cystic fibrosis | American Society of Microbiology

9. How long do patients with cystic fibrosis live? | Cystic-Fibrosis.com

The author, Claire Bonneau, is a medical writer and certified trauma operating room nurse.