In the mid-1800s, British obstetrician Sir James Young Simpson argued that infections after surgical procedures were closely related to deficiencies in hospital design, ventilation, and management. Simpson observed the negative effects of overcrowding in hospitals and studied the correlation between poor hospital conditions and mortality rates. He used the term hospitalism to describe “the hygienic evils which the system of huge and colossal hospital edifices has hitherto been made to involve.” John Aiken, another eighteenth-century physician, suggested that hospitals might be “gateways to death.”
Today, we benefit from healthtech innovations, advances in identifying the causes and treatments of infectious diseases, and widespread adoption of antiseptics and antibiosis practices. Nevertheless, about one in 31 hospital patients develops a healthcare-associated infection (HAI) in the United States on any given day. Worse still, 99,000 patients die of HAIs each year.1,2
HAIs (also known as nosocomial infections) are infectious diseases not present or incubating at admission and contracted within a healthcare environment. They are caused by viral, bacterial, and fungal pathogens, and transmission usually occurs via medical interventions, hospital equipment, and healthcare worker and patient exposure. The most common sites of infection are the bloodstream (central line-associated bloodstream infections or CLABSI), lungs (ventilator-associated pneumonia or VAP), urinary tract (catheter-associated urinary tract infections or CAUTI), and surgical wounds (surgical site infections or SSI).
Though any bacteria may cause HAIs, there is an alarming rate of multidrug-resistant organisms (MDRO) causing HAIs. This increase is due to the misuse and overuse of antibiotics as well as poor hygiene measures and compliance. Commonly seen HAI-causing pathogens include methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and Clostridioides difficile (C. difficile). 3
A C. difficile infection (CDI) is of great concern because people with other illnesses, people taking antibiotics, or the elderly are at a greater risk of experiencing adverse health outcomes after contracting it. C. difficile is a bacterium that causes an infection of the large intestine, leading to severe diarrhea and colitis. It also forms highly resistant spores that easily persist in the affected person and disseminate through fecal-oral routes despite routine and terminal cleaning of hospital settings. Antibiotics that fight bacterial infections by killing bad microorganisms can disturb the balance of good microorganisms that populate the large intestine and would normally protect the body against harmful infections like CDI. This conundrum allows C. difficile to grow and release toxins that cause colon inflammation. The longer a patient is on antibiotics (which affects the levels of good microorganisms), the greater the risk of developing CDI.
Although the epidemiology of CDI has evolved over time, age has emerged as one of the most important risk factors for CDI in healthcare settings in recent years. The reasons for this correlation are multifaceted and include factors such as lower immune response, comorbidities, and antibiotic exposure. It has been suggested that the incidence of CDI in persons > 65 years of age contributed to over 80% of all deaths from CDI in recent years – an alarming and disproportionally high figure. 4,5
Emerging HAI-causing pathogens are also of concern. Candida auris (C. auris) is a multidrug-resistant (also called superbug) fungus that can lead to invasive infections and is associated with high mortality. C. auris can only be identified in highly specialized laboratories and is difficult to eliminate and treat. Patients often remain colonized with this potentially deadly pathogen for extended periods, sometimes indefinitely, while shedding the fungus and contaminating their immediate environment. Since C. auris was first reported in 2016, there were 3,270 clinical cases (in which infection is present) and 7,413 colonization cases where individuals carry the organism somewhere on their bodies without signs of active infection. Clinical cases have increased each year, with the most rapid rise occurring during 2020-2021. COVID-19 may have contributed to these numbers, as some patients required intubation and other invasive procedures that put them at higher risk of infection. This month, the CDC acknowledged C. auris as an urgent threat. 6,7,8
HAIs contribute significantly to the overall burden of disease in the United States, but if their impact wasn’t enough, as of March 2023, there have been over 103 million confirmed COVID-19 cases and more than 1.1 million deaths related to COVID-19 in the country. Additionally, it is estimated that up to 30% of COVID-19 survivors experience post-acute sequelae of SARS-CoV-2 infection (PASC), which can persist for months after the initial infection and severely impact the quality of life for those affected. These staggering numbers highlight the devastating consequences of the pandemic on our society. Economically, businesses faced severe challenges, with many small and medium-sized enterprises forced to shut their doors permanently. In the education sector, schools have faced challenges with staff shortages due to illness, high rates of absenteeism, school closures, and a sizable drop in math and reading scores. The digital divide further widened, as not all students had equal access to technology and resources to attend online classes. It is clear that the pandemic’s long-lasting effects on our society will continue to be felt in the years to come. 9, 10, 11
Enhanced Pathogen Mitigation Strategies Are Here to Stay
In hospitals and public settings, infections can be limited through adherence to infection prevention and control protocols, and surveillance. The Centers for Disease Control and Prevention (CDC) advises hospitals and community buildings on how to disinfect facilities. The use of chemical disinfectants, including alcohols, chlorine and chlorine compounds, formaldehyde, glutaraldehyde, ortho-phthalaldehyde, hydrogen peroxide, iodophors, peracetic acid, phenolics, and quaternary ammonium compounds, remains an essential control measure in hospitals. In community settings and most non-healthcare buildings, room ventilation along with installing air purifiers and updating heating, ventilation, and air conditioning (HVAC) systems are considered critical layers of defense against airborne pathogens to complement less astringent chemical disinfection protocols. However, there are far too many situations where chemicals and traditional ventilation/filtration are inadequate to prevent infection transmission:
- Excessive use of chemical disinfectants represents a potential health hazard to building occupants.
- Current HVAC systems cannot deliver increased ventilation without system upgrades that may be too expensive, time-intensive, energy-consuming, or disruptive to occupants.
- Maintenance needs (e.g., replacing HEPA/MERV filters, inspecting HVAC systems) are too demanding or too expensive.
- Increased energy consumption and greenhouse gas emissions that are expensive and counter to most organization’s sustainability and decarbonization goals.
- The overall chemical and filtration/ventilation efficacy in high-risk environments can be limited by contact time, filtration efficacy, and HVAC settings.
The incorporation of germicidal ultraviolet-C light (UVGI) in building operations is a new reality and an essential step to prevent the spread of infectious diseases. UVGI is a disinfection technology that has received renewed interest during the COVID-19 pandemic after decades of use in advanced water disinfection systems across the globe. UVGI is a region of the ultraviolet-C (UV-C) spectrum that has been known to inactivate microorganisms by damaging their deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). When UVGI is absorbed by DNA/RNA, the resulting photodamage renders the target microorganism incapable of replicating and harmless. UVGI light can be used to disinfect air, water, and surfaces.
In a randomized, controlled clinical investigation funded by the CDC, researchers observed a significant reduction in the relative risk of colonization and infection when UVGI was paired with standard disinfection protocols for terminal room disinfection. The incidence of MRSA, VRE, CDI, and multidrug-resistant Acinetobacter was over 30% lower among exposed patients after adding UVGI to standard cleaning strategies. Controlled studies starting in the 1960s have also demonstrated that upper-room UVGI devices can be used effectively against airborne pathogens, including to prevent the epidemic spread of measles and SARS-CoV-2 in schools. Measles is one of the most contagious of all infectious diseases; up to 9 out of 10 susceptible persons with close contact to a measles patient will develop measles. Upper-room UVGI fixtures are installed above people in rooms to create a disinfection zone of UV-C energy that inactivates airborne pathogens released in the room without exposing the people below the disinfection zone to UV-C. The effectiveness of upper-room UVGI increases as air mixes between the upper and lower room. The CDC has long endorsed upper-room UVGI use for Mycobacterium tuberculosis control and recommends the use of upper-room UVGI to help control SARS-CoV-2 and other infections. 12, 13, 14, 15
- Safe: UVGI devices adhere to threshold Limit Values (TLVs) published by the American Conference of Governmental Industrial Hygienists (ACGIH). This means that UVGI devices are commissioned to comply with safe levels of UV-C exposure. Modern UVGI devices are also equipped with motion sensors for added safety to eliminate the risk of accidental exposure and are certified for zero ozone emission.16, 17
- Evidence based: Danish doctor Niels Finsen, pioneer of phototherapy, won the 1903 Nobel Prize in medicine for his work using ultraviolet radiation to heal tuberculosis lesions. Since then, numerous studies have demonstrated the efficacy of UVGI to inactivate contact and airborne pathogens, and to prevent the spread of infection. UVGI devices are commonly used for point-in-time disinfection in high-risk settings (i.e., patient rooms, classrooms) and continuous disinfection in occupied spaces (i.e., cafeterias, waiting rooms, restrooms). The effectiveness of these devices can be measured in equivalent air changes per hour (eACH) to provide a familiar comparison with the traditional ventilation approach and can easily achieve 6+ eACH in most spaces.18, 19
- Regulated: UVGI devices are federally regulated by the US Environmental Protection Agency (EPA) under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Federal regulations require devices to be produced in an EPA-registered establishment and there are production reporting and label requirements. All claims in connection with the sale or distribution of a UVGI device must be supported with efficacy data. 20
- Intelligent and Affordable: Expensive UVGI towers and upper-room devices are a thing of the past. With the increased demand for this technology during the pandemic, new UVGI devices are incredibly affordable and also IoT enabled for actionable insights and compliance. 21
Healthy Indoor Spaces are the New Normal
Implementation of effective and sustainable infection prevention programs remains an ongoing priority for building operators and is the new normal for building occupants. The COVID-19 crisis has challenged institutions to rethink their approaches to infection prevention and control. Traditional preventive measures to reduce infection include hand hygiene, antibiotic stewardship, contact precautions, appropriate antimicrobial prophylaxis, and enhanced filtration and ventilation. Monitoring the local determinants of infectious disease burden, global trends, and promoting education and accountability are also key means of managing infectious diseases. Despite these measures, the human cost of preventable infections remains too high, and we must do and expect more. As we evolve into a society where indoor pathogen mitigation standards are poised to become code enforceable over the next 12 months, it is crucial to embrace enhanced prevention measures, such as UVGI. By doing so, we can strive to reduce the burden of preventable infections and improve health outcomes for all.22
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