Many factors make the isolation precautions for diseases like COVID-19 more complex than typical droplet or airborne definitions.
Standard precautions have a long history in healthcare, being practiced in some form since the Middle Ages. The Centers for Disease Control and Prevention (CDC) formalized these precautions into what was then called universal precautions in response to the HIV epidemic in the late 1980s. Universal precautions were focused on protecting healthcare workers from blood borne pathogens, focusing on the use of personal protective equipment (PPE) such as gowns and gloves. The concept treats all blood and body fluids as potentially infectious. Universal precautions were revised and became standard precautions in 1996 and became more inclusive of an overall infection prevention aspect when engaging in patient care. Respiratory hygiene was added to standard precautions in 2007, in recognition of the increasing risk of respiratory spread of illnesses such as pandemic influenza.
Transmission based precautions were developed in the 1970s, and were revised to be a next higher level of precautions for those infectious diseases that were spread through contact, droplet and airborne transmission. The emergence of antimicrobial resistant pathogens drove the need to update standard precautions so that healthcare environments could prevent transmission as well as keep providers safe. Just as the need for transmission-based precautions was driven by emergence of pathogen resistance, it is now time to look again at the concept of standard and transmission-based precautions and determine if additions or changes are needed in the wake of the COVID-19 pandemic.
Recent outbreaks and epidemics have shown that infection prevention needs to become more sophisticated with standard precautions, travel history and general awareness of national and international epidemiology and diseases of public health concern. Over the last two decades, the majority of the significant outbreaks was due to viral respiratory illnesses (severe acute respiratory syndrome (SARS), middle eastern respiratory syndrome (MERS), avian influenza). The SARS epidemic in part prompted the CDC to update the standard precautions to include respiratory etiquette.
In these recent outbreaks, and the current pandemic, healthcare workers (HCWs) are at increased risk for acquiring the infections purely as a result of doing their jobs. Data has shown that HCWs made up roughly 20% of cases in the SARs outbreak and 18% in the MERS outbreak.1 It is still unknown how many HCWs have become infected in the COVID-19 pandemic, but current estimates as of this writing are greater than 65,000 cases.1 Many factors can contribute to HCW infections, but often early in outbreaks and pandemics, lapses in infection control practices play a major role. Not having the appropriate type or amount of PPE, lack of isolation of infectious patients, and lack of awareness of epidemiological risk factors, such as recent travel or congregate living status, all play a part. With any type of outbreak, there is always an initial gap in awareness and understanding of the pathogen, transmission factors, and virulence. At this time is when HCWs can be most vulnerable and the outbreak has the potential to grow from a local or regional level. It is during this time when traditional application of standard precautions may not be enough.
Recent articles in the press have been debating the role of airborne transmission in COVID-19 spread.2 While there is not a clear consensus, what does appear to be clear is the need to develop more nuanced definitions of droplet and airborne transmission. The desire to have a very mutually exclusive and clear separation of the types of transmission makes it easier to educate, implement, and monitor. However, science shows that it is more of a continuum that is impacted by many variables, which leaves much up to the bedside practitioner to evaluate and assess risk levels.
Environmental factors, such as humidity level, air exchanges, pressure differentials, can all impact the amount of aerosolization that can occur with respiratory droplets.3 Patients themselves impact, with activity levels, cough etiquette and other host factors that can potentially impact communicability of the virus. The strain of the virus can be more infectious than others, which is not known at the time of admission to the healthcare facility. Manipulations and treatments that are done to the patients also impact the ability of aerosolization, such as oxygenation modalities, endotracheal intubation, bronchoscopies or nebulizing medication treatments.4 All of these factors make the isolation precautions for diseases like COVID-19 more complex than typical droplet or airborne definitions.
With the knowledge that respiratory illnesses have been the greatest international impact on recent outbreaks, it is time to again review the items included in standard and transmission-based precautions and potentially include some variation of universal masking for patient encounters. In particular, this may be most essential in frontline areas, such as emergency departments, urgent care centers, ambulances and first responders, where there is no known history for the patient and unknown exposure risks. Also, in areas where many aerosol generating procedures are occurring, such as intensive care units, procedural areas, respiratory care units and dental clinics.
Another difficult lesson learned from the COVID-19 pandemic is the inadequate supply of respirator options that are available across the healthcare continuum for staff. Traditional N95 masks that require fit testing were in short supply as the pandemic ratcheted up. In even shorter supply were other types of respirators that did not require fit testing, such as PAPRS, CAPRS and other full-face respirator options.
And with almost all of these types of respirators, there are still contraindications for use, such as facial hair, eyeglasses, severe asthma, or other health conditions of the worker. This has revealed a long feared weak link in the ability of a facility to provide adequate protection to all its healthcare workers at the most crucial time it is needed. Efforts to increase not only the availability of current respirators, but also develop new technologies that offer the same level of protection, but have more universal fit and application to a wide variety of users, should be a push from manufacturers and vendors for healthcare and other essential workers.
More research is needed in the field of disease transmission, and in particular for respiratory illnesses. Many studies are based on animal models, which have limitations with human physiology, or are lab-based, which have limitations in real-world scenarios. Understanding of how effective the airborne or aerosol spread is for various respiratory diseases would provide much needed information on how best to develop transmission-based precautions that are effective. A review of the current recommendations of airborne precautions would also elucidate which components are most effective in breaking the chain of disease spread.
And based on these types of data, precautions for specific viral illness could be more specific and also more customizable based on transmission factors. However, until that time comes, and with the continued threat of emerging viral respiratory pathogens, consideration of universal masking guidelines as part of standard precautions may be the beginning of another evolution of how we approach infection prevention practices in healthcare organizations.
REBECCA LEACH, RN, BSN, MPH, CIC, has been an infection preventionist since 2010, with a background in nursing and epidemiology. Leach, a member of Infection Control Today®’s Editorial Advisory Board, currently works at a healthcare system in Phoenix that includes 5 hospitals and more than 100 outpatient treatment centers.