COVID and RSV HEADER

COVID and RSV

Cite this article as:
Laura Riddick, Damian Roland and Andrew Tagg. COVID and RSV, Don't Forget the Bubbles, 2021. Available at:
https://doi.org/10.31440/DFTB.33694

There was a time, perhaps a century ago, when the only virus we really worried about was RSV. Children, snot dripping from their noses, would come in coughing, and struggling to breath and, as days grew shorter and nights grew longer we knew that bronchiolitis season was upon us once more.

But things have changed. We worry about a different virus now and there is plenty of evidence to show that the usual seasonal variations in RSV have flattened. It was heartening to see the data showing that the mid-winter peak was no more as we kept ourselves to ourselves. Non-pharmacological interventions – physical distancing, respiratory hygiene and restricted movements – meant that the scourge of the paediatric emergemcy department was held at bay. Until…

Half a world away…

Bronchiolitis presentations peaks in June – July in Australia (remember it is our winter in the Southern hemisphere). Last season there was a 98% reduction in RSV (and a 99.4% reduction in cases of influenza (Yeoh et al., 2020). But let’s take a look at the surveillance data from Western Australia to see what has been going on of late.

Western Australia RSV incidence- Based on Foley et al. 2021

McNab et al. (2021) looked to see what had been going on in Victoria, a state that had much stricter lockdown measures than WA. Whilst there was clear suppression of the winter cases of bronchiolitis, these began to increase by the beginning of the year, coinciding with the return to school after the long Christmas break Normally, in February, the Royal Children’s Hospital would return 5.6% positive RSV swabs. In 2021, they returned 32.8%. More worryingly, this peak is higher than the pre-COVID winter peak (30.4%)

RSV incidence in Victoria
Victorian Australia RSV incidence- Based on McNab et al. 2021

But this snapshot doesn’t give you the whole picture. Let’s just slide the data along a few short weeks…

Victorian Australia RSV incidence- Based on McNab et al. 2021

These data have been echoed all over Australia and New Zealand with a ramping up of out of season RSV positive cases. What is most concerning is that numbers appear to be higher than the usual peak and the patients older (mean 18.2 months compared to 7.3 – 12.5 months). Why could this be? It could be, as Foley et al. (2021) suggests due to an increase in RSV-naïve babies born during that first wave coupled with waning herd immunity.

What does this mean for paediatricians in the Northern hemisphere who are about to face this surge in cases?

Getting started?

Paediatricians at the frontline need to be able to see what is going on and so PERUKI will shortly be launching BronchSTART. The aim of this prospective observational study is to both track the potential surge so that health policy is informed as much as possible but also to describe its epidemiology. As highlighted above the data suggests a potentially wider age range and steeper spike but these are from retrospective studies By reporting potential cases (in children under two years of age) presenting to over 50 Emergency Department across the UK, in real-time, clinicians and researchers will be able to really understand the impact and outcomes of this respiratory disease.

Given the challenges of identifying and managing children who may have RSV, COVID-19, or both, some guidelines have been produced by the RCPCH.

What do the guidelines say?

The RCPCH guidelines focus on THREE key areas:-

  • Reducing hospital attendances with mild cases
  • Pathways and guidance for testing and cohorting
  • Minimising patient time on High flow and reducing the exposures to AGPs

The guidelines are designed to reduce potential unnecessary referrals from primary care to the emergency department. Hopefully, reducing the number of children presenting (and then mixing with each other in the waiting room) will lessen the burden on paediatric emergency departments. It offers a traffic light system for reviewing patients, with suggestions of how to manage some borderline cases in the community with secondary care input.

NHS bronchiolitis pathway

When it comes to testing, the aim is to be able to minimise the spread of COVID-19 and protect clinically vulnerable children.  As with what is happening in most hospitals, the recommendation is to only test patients being admitted to the hospital. Any further testing is then influenced by the patient’s condition and the prevalence of COVID in the hospital, as well as cubicle availability.  

Using Point-of-Care-Testing (POCT)/rapid testing for patients going to PICU and HDU may limit cubicle occupancy, and improve cohorting of patients. Additional COVID testing then should be considered in cases where respiratory panels are negative (or suggest low-risk causative organisms such as bocavirus or rhinovirus). Additional testing should also be considered if aerosol-generating procedures (AGPs) are required or parents are displaying symptoms. 

Given that AGPs provide a high risk for transmission, the recommendation is for rapid but weaning of high-flow with guidance provided by north and south Thames retrieval service protocol used.

For those of us in clinical practice, the guidelines remain largely unchanged. Non-pharmacological measures- physical distancing, good respiratory hygiene and use of appropriate PPE are key. Cohorting patients into red and blue, hot and cold or low/high-risk zones may add some value unless physical distancing can be maintained.

As case numbers rise, and cubicle capacity becomes an issue then departments need to come up with a risk mitigation strategy to protect the vulnerable.

  • Weekly testing for all prolonged stays 
  • Test if there are new symptoms 
  • More emphasis on risk assessment for use of RPEs (respiratory protective equipment) 
  • If single room capacity is exceeded, patient may be risk assessed for cohorting 
  • If respiratory virus +ve and COVID –ve patients can be cohorted even if requiring an AGP  
  • We still need to advise those DC’d from CAT/ED with respiratory symptoms of the need for COVID testing via track and trace
  • Parents should not be in hospital if symptomatic. Do not test asymptomatic parents
COVID and RSV flow chart

Bottom line

  • Support community services to reduce strain on hospital services
  • Use testing to help cohort and plan patient care
  • Wean or reduce AGPs where safe to do so
Infographic depicting RSV and COVID guidelines

Selected references

Foley, D.A., Yeoh, D.K., Minney-Smith, C.A., Martin, A.C., Mace, A.O., Sikazwe, C.T., Le, H., Levy, A., Moore, H.C. and Blyth, C.C., 2021. The Interseasonal Resurgence of Respiratory Syncytial Virus in Australian Children Following the Reduction of Coronavirus Disease 2019–Related Public Health Measures. Clinical infectious diseases: an official publication of the Infectious Diseases Society of America.

Huang QS, Wood T, Jelley L, et al. Impact of the COVID-19 nonpharmaceutical interventions on influenza and other respiratory viral infections in New Zealand. Nat Commun. 2021;12:1001. https://doi.org/10.1038/s41467-021-21157-9

McNab, S., Do, L.A.H., Clifford, V., Crawford, N.W., Daley, A., Mulholland, K., Cheng, D., South, M., Waller, G., Barr, I. and Wurzel, D., 2021. Changing Epidemiology of Respiratory Syncytial Virus in Australia-delayed re-emergence in Victoria compared to WA/NSW after prolonged lock-down for COVID-19. Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America.

Oh, D.Y., Buda, S., Biere, B., Reiche, J., Schlosser, F., Duwe, S., Wedde, M., von Kleist, M., Mielke, M., Wolff, T. and Dürrwald, R., 2021. Trends in respiratory virus circulation following COVID-19-targeted nonpharmaceutical interventions in Germany, January-September 2020: Analysis of national surveillance data. The Lancet Regional Health-Europe6, p.100112.

Public Health England. Weekly national Influenza and COVID19 surveillance report: Week 49 report (up to week 48 data) 3 December 2020. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/940878/Weekly_Flu_and_COVID-19_report_w49.pdf. Accessed July 20, 2021.

Tang, J.W., Bialasiewicz, S., Dwyer, D.E., Dilcher, M., Tellier, R., Taylor, J., Hua, H., Jennings, L., Kok, J., Levy, A. and Smith, D., 2021. Where have all the viruses gone? Disappearance of seasonal respiratory viruses during the COVID-19 pandemic. _Journal of Medical Virology

Waterlow, N.R., Flasche, S., Minter, A. and Eggo, R.M., 2021. Competition between RSV and influenza: Limits of modelling inference from surveillance data. Epidemics35, p.100460.

Williams, T.C., Lyttle, M.D., Cunningham, S., Sinha, I., Swann, O.V., Maxwell-Hodkinson, A. and Roland, D., 2021. Study Pre-protocol for “BronchStart-The Impact of the COVID-19 Pandemic on the Timing, Age and Severity of Respiratory Syncytial Virus (RSV) Emergency Presentations; a Multi-Centre Prospective Observational Cohort Study”. Wellcome Open Research, 6(120), p.120.

Yeoh DK, Foley DA, Minney-Smith CA, et al. The impact of COVID-19 public health measures on detections of influenza and respiratory syncytial virus in children during the 2020 Australian winter. Clin Infect Dis 2020.

Aerosol Generating Procedures

Cite this article as:
Tagg, A. Aerosol Generating Procedures, Don't Forget the Bubbles, 2020. Available at:
https://dontforgetthebubbles.com/aerosol-generating-procedures/

As more cases of Covid19 present to health care facilities across the world, there seems to be some confusion as to what is an aerosol-generating procedure. Turning up to work is not without risk with a large number of healthcare workers in Italy and Ireland. diagnosed with COVID19. There is a case report of asymptomatic carriage lasting up to 16 days so we need to be careful whether the child in front of us has been diagnosed with COVID19 or not.

A lot of the data we have comes from the 2003 SARS epidemic and the H5N1 influenza outbreaks. There are always going to be a number of confounding variables when looking at these reports – whether the HCW was wearing appropriate PPE (or had access to it), how good their hand-washing was, how close together patients are – but nosocomial infections do occur.

First off,  we are going to take a look at what an aerosol is, then how aerosols and droplets relate to some common, and uncommon, things we do in paediatrics.

 

Aerosol or droplet?

Let’s define some terms before we get started – not as easy as it sounds, it turns out.

A  respiratory droplet is a fluid bundle of infectious particles that travels from the respiratory tract of the infected individual onto the mucosal surface of another, rather than floating down the respiratory tract. Small droplets are between 5-20μm and tend to hang up around the glottis. Large droplets are > 20μm and are probably too big to follow airflow. They tend to obey the laws of gravity and so settle on nearby surfaces when you sneeze. If you inadvertently touch the same surface then touch your face you can potentially transmit the infection. This is why we wash our hands. In healthcare, droplet precautions include a surgical mask, eyewear, disposable gown, and gloves. The surgical mask acts as a physical barrier to droplets that are too large to be inhaled.

A droplet nucleus is what is left once the liquid rapidly evaporates from a droplet. They are in the order of 10μm in diameter and are in the respirable range. This is generally defined as any particle less than 10μm. The inspirable range is defined as anything between 10 – 100μm in size.

An aerosol is a liquid (or solid) suspended in the air – think mist and fog. These small particles are less than 5μm and so are in the respirable range (rather than the inspirable range like droplets) and can enter the lower respiratory tract. They are affected by diffusion rather than gravity so tend to hang around for a while.  Measles is one such airborne disease. A recent letter in the NEJM suggests that SARS-CoV-2 can remain viable in aerosols for at least 3 hours, though the WHO’s guidance is clear that it should be managed with droplet and contact precautions UNLESS you are performing an aerosolising procedure.

Consider them on the continuum of aerosol -> small droplets -> large droplets -> puddles. Aerosols and small droplets have the ability to travel fair distances, especially if powered by a blast of oxygen or expired air. Larger droplets tend to obey the laws of gravity and settle on surfaces.

 

Just breathing, coughing and sneezing

But even putting an oxygen mask on the patient may not protect you. Hui et al. (2006) used fancy laser beams and smoke to detect just how far a single breath might travel.  With a standard oxygen mask on the patient and a flow rate of 4l/min, a tidal volume of 500mls, and 12 breaths a minute the smoke plume traveled approximately 0.45m. In most experiments, scientists use smoke as a stand-in for the more nebulous breath of air. Non-biological aerosols will behave differently depending on the airflow and ventilation in the room and have a constant density. Mathematical modelling would suggest that the further from the source a sample is taken then the lower the potential infectivity until a state of equilibrium is reached. Fortunately, the air is exchanged in most hospital rooms on a regular basis.

A patient that is coughing and sneezing can produce large, short-range droplets and small, long-range aerosols. The aerosols produced by coughing are heavier than the smoke used in experiments so hopefully, they may not be able to travel as far. Experimental data will tend to over-estimate the spread of droplets.

Thompson et al (2013) took 99 air samples around presumptive AGPs. 26.1% of them contained viral RNA. But the baseline level of contamination, when no AGPs (as defined by WHO 2009) were performed was 10.5%. Just because a procedure might generate an aerosol, it does not hold true that the aerosol can cause an infection.

Most of the data we have comes from the fast SARS-CoV epidemic in 2002-2003. Tran et al. tried to find all of the papers related to HCW infection and aerosol-generating procedures. They found 10 – 5 non-randomized cohort studies and 5 retrospective cohort studies. They then created pooled estimates of odds ratios.

Judson and Munster usefully categorized AGPs into those that mechanically create and disperse aerosols and those that make the patient wriggle and cough. Or you could think of them, as suggested by Brewster et al. (2020) as those procedures that require gas flow and those that require no extrinsic gas flow.

 

 

Bag-valve-mask ventilation and CPR

High risk 

A paediatric cardiac arrest is uncommon. When it occurs your first move* should be to open the airway and provide rescue breaths. In this time of COVID19, I doubt anyone is going to be doing mouth-to-mouth/nose ventilation. They are going to reach for an appropriately sized bag-valve-mask. Just like when placing a standard oxygen mask, there is a transverse movement of droplets even with a reasonable seal. The addition of an HME filter does appear to attenuate some of this, as demonstrated by Chan et al.(2018).

Adapted from Chan MT, Chow BK, Lo T, Ko FW, Ng SS, Gin T, Hui DS. Exhaled air dispersion during bag-mask ventilation and sputum suctioning-Implications for infection control. Scientific reports. 2018 Jan 9;8(1):1-8.

 

Adult CPR guidelines are advocating for chest compression-only CPR in the community and rapid intubation pre-compressions if circumstances allow. There has been little guidance on paediatric CPR from the ALSG but a number of enterprising teams are looking at it.

Possible cases of SARS transmission by CPR have been reported (Christian et al. 2004) but BVM ventilation took place during the cases and this may be the most important factor for possible viral transmission.

 

Intubation

High risk 

Anything, where the clinician is inches away from the respiratory tract of the patient, is going to be a high-risk procedure. There have been huge collaborative efforts worldwide creating COVID intubation algorithms. They share a lot of commonalities.

  • The most experienced operator performs the procedure – this is not a time for learning
  • No bag-valve-mask ventilation prior to intubation
  • Use of videolaryngoscopy to maximize the distance between intubator and patient
  • Minimum number of staff present

This is my favourite paediatric intubation resource from Queensland Children’s Hospital.

 

Nebulizing a medication

High risk / Unclear evidence

There are few indications for nebulizing medication. Bronchodilators are best delivered by MDI and spacer when possible but in cases of severe asthma or perhaps, more commonly, in croup, a nebulizer chamber may be the way to go. The UK guidelines do not consider the delivery of nebulized medications as an AGP. The rationale behind this is that the aerosol is derived from a non-patient source. Even if they do have the disease the medication sticks to the mucus membranes and so will not get released into the general environs. There seems to be a lack of global consensus on this.

Nebulizers generate small particles, between 1-5microns in diameter, in order to get down into the bronchioles and not just be deposited in the oropharynx. Viable COVID19 viral RNA has been detected in aerosol form 3 hours after delivery by nebulizer in experimental conditions but this does not prove infectivity, just infectious potential.

In 2009 O’Neill et al. performed air sampling studies for common patient activities, including making the bed and providing nebulized therapy, as well as some more invasive treatments (bronchoscopy and suctioning). Although small numbers they found an increase in influenza particle numbers (from baseline) of up to 70,000/cm³.

 

High Flow Nasal Cannula

High risk 

In adult practice, high flow oxygen delivery is anything over 6l/min. In paediatrics, it is 2l/kg/min up to the adult maximum of 60l/min. In one of my favourite studies to date (and certainly in keeping with the DFTB ethos) five anaesthetists gargled 10mls of red food dye, inhaled to their vital capacity and then coughed. They then repeated the experiment using blue food dye and HFNC at 60l/min and compared the distance traveled. They showed a baseline cough distance of 2.48m increasing up to 2.91m with high flow. Of course, children have a much smaller vital capacity.

This is in contradiction to the data from Hui et al. (2019). They used a human-patient-simulator (as opposed to humans in the above study), smoke and lasers. With a properly fitted mask flow forward flow was increased to ~26 cm with 5cm of CPAP and to around 33cm with 20cm of CPAP. With HFNC the exhalation distance increased from 6.5cm (10l/min) to ~17cm (60l/min). When the mask became loose or disconnected smoke was detected up to ~62cm laterally.  So why the big difference in the studies? It is the cough that causes the problem.

This video from Sick Kids in Toronto says more than any words ever could.

Whether you believe in the benefits of high-flow or not, pushing oxygen through the nose at 2l/kg/min and out through the mouth can create an aerosol spread of snot and virus. We would advise that it is only be used in cases where low flow oxygen therapy has failed. It also makes sense then, that it should only be started in the place where the patient is going to end up. It would not be wise to start a patient on HFNCO2 then wheel them through the hospital leaving a cloud of viral particles in their wake like some overactive Bisto Kid. And if you are going to do it with a coughing patient then it would be sensible to put a standard face mask on first.

 

Non-invasive ventilation (CPAP or BiPAP)

High risk 

High flow nasal cannula seems to have superseded non-invasive ventilation in many cases, though CPAP is regularly used in neonatal practice. There is very little evidence for maternal transmission of COVID19 and one might suppose that full PPE is then not warranted. However, you need to consider where the baby has come from.

Open suctioning and chest physiotherapy

High risk 

Removal of nasal foreign body

Medium to high risk

There are lots of ways to remove a nasal foreign body but all of them will generate snot. The old standby – the mother’s kiss – is, realistically, no more dangerous for the parent than living in close proximity. If your pre-encounter probability of infection with SARS-CoV-2 is low, i.e. there is little community transmission, then the risk to the provider is probably low.

Nitrous oxide

Medium to high risk 

Respiratory illness is a contra-indication to nitrous sedation but given that there is a degree of asymptomatic carriage it is not impossible that we might need to use it. With children not going to school and being told to stay away from their friends, there is going to be a spike in trampoline and bunk-bed related injuries. Again consideration should be made as to the possibility of community transmission. Logically holding a continuous flow mask on an uncooperative toddler would expose a HCW to higher risk than being a room Sith a cooperative patient using a demand system with appropriately attached to suction.

Examining the throat

Medium to high risk 

In normal times, no paediatric examination is complete without looking in the ears, nose, and throat, no matter how hard it might be. You can argue that looking at tonsils might not be overly helpful, given that the inter-rate variability is pretty high but there are other things to look for too – emerging teeth, Koplik spots, ulcers. But does a look in the throat put us at risk?

The Royal College of Paediatric and Child Health concurs, and in a statement put out on the 24th of March suggest that we only look in the throat if it is essential. If we have to do it we should be wearing appropriate protection (glove, gown, surgical face mask). If a child is at particularly high risk then they recommend empiric antibiotics.

Even ENT experts, like Eric Levi, recognize the unique risks that fiddling around near the upper respiratory tract hold.

Inserting a nasogastric tube

Medium to high risk

The combined Colleges of Surgeons of Great Britain and Ireland suggest that insertion of a nasogastric tube in an adult is an AGP, probably as it may induce coughing.

Taking a nasopharyngeal swab

Low to moderate risk 

The CDC state that collecting a nasopharyngeal swab doesn’t need to take place in an isolation room but should at least be performed in a single room with a closed door. The health care practitioner should wear an N95 mask or equivalent, coupled with eye protection, gloves, and gown. Given how far the swab has to travel up the nasopharynx nobody should be surprised that it might make someone sneeze.

The current Australian guidance contains slightly different advice.

 

We can also add things like IV access, suprapubic aspiration and performance of a lumbar puncture to this list of LOW-risk procedures.

And let’s not forget our surgical and dental colleagues

Surgical procedures

Clearly, some surgical procedures are more dangerous than others. Eric Levi. advocates for a risk assessment before any procedure takes place, starting with ‘Does it need to be done now?” Take a look at his post on how he is modifying his operative technique in order to reduce risk to himself and his colleagues.

On the 25th of March, the combined Colleges of Surgeons of Great Britain and Ireland recommended against laparoscopic surgery due to the potential for aerosol formation. Endoscopy, at either end, also has the potential for the creation of fomites and aerosolizing droplets and so should be carried out with extreme caution.

Dental procedures

There are very few dental procedures that need to be performed as an emergency but given that high-speed drills can lead to aerosolization have a care for our dental colleagues that may also be exposed in the course of duty.

The guidance for these procedures is common sense. Don’t perform them if you don’t have to. This is not the time for some minor dental procedures. If they have to be carried out then it should happen in the appropriate space with the appropriate staff. This means in a single room (ideally) with the minimum number of staff wearing appropriate PPE.

 

These are our thoughts, based on the current evidence, and we’d love you to persuade us otherwise in the comments below.

*Clearly the first step of the algorithm is D for Danger. That means putting on your PPE.

Selected references

Bourouiba L. Turbulent Gas Clouds and Respiratory Pathogen Emissions: Potential Implications for Reducing Transmission of COVID-19. JAMA. 2020 Mar 26.

Brewster DJ, Chrimes NC, Do TB, Fraser K, Groombridge CJ, Higgs A, Humar MJ, Leeuwenburg TJ, McGloughlin S, Newman FG, Nickson CP. Consensus statement: Safe Airway Society principles of airway management and tracheal intubation specific to the COVID-19 adult patient group.

Brown JS, Gordon T, Price O, Asgharian B. Thoracic and respirable particle definitions for human health risk assessment. Particle and fibre toxicology. 2013 Dec 1;10(1):12.

Davies A, Thompson G, Walker J, Bennett A. A review of the risks and disease transmission associated with aerosol generating medical procedures. J Infect Prev 2009; 10:122–6.

van Doremalen N, Bushmaker T, Morris D, Holbrook M, Gamble A, Williamson B, Tamin A, Harcourt J, Thornburg N, Gerber S, Lloyd-Smith J. Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1. medRxiv. 2020 Jan 1.

Hui DS, Ng SS. Recommended hospital preparations for future cases and outbreaks of novel influenza viruses. Expert Review of Respiratory Medicine. 2020 Jan 2;14(1):41-50.

Hui DS, Ip M, Tang JW, Wong AL, Chan MT, Hall SD, Chan PK, Sung JJ. Airflows around oxygen masks: A potential source of infection. Chest. 2006 Sep 1;130(3):822-6.

Judson SD, Munster VJ. Nosocomial Transmission of Emerging Viruses via Aerosol-Generating Medical Procedures. Viruses. 2019 Oct;11(10):940.

Kam KQ, Yung CF, Cui L, Lin Tzer Pin R, Mak TM, Maiwald M, Li J, Chong CY, Nadua K, Tan NW, Thoon KC. A well infant with coronavirus disease 2019 (COVID-19) with high viral load. Clinical Infectious Diseases. 2020 Feb 28.

Liu Y, Ning Z, Chen Y, Guo M, Liu Y, Gali NK, Sun L, Duan Y, Cai J, Westerdahl D, Liu X. Aerodynamic Characteristics and RNA Concentration of SARS-CoV-2 Aerosol in Wuhan Hospitals during COVID-19 Outbreak. bioRxiv. 2020 Jan 1

Macintyre CR, Seale H, Yang P, Zhang Y, Shi W, Almatroudi A, Moa A, Wang X, Li X, Pang X, Wang Q. Quantifying the risk of respiratory infection in healthcare workers performing high-risk procedures. Epidemiology & Infection. 2014 Sep;142(9):1802-8.

Noti JD, Lindsley WG, Blachere FM, Cao G, Kashon ML, Thewlis RE, McMillen CM, King WP, Szalajda JV, Beezhold DH. Detection of infectious influenza virus in cough aerosols generated in a simulated patient examination room. Clinical Infectious Diseases. 2012 Jun 1;54(11):1569-77.

Seto WH. Airborne transmission and precautions: facts and myths. Journal of Hospital Infection. 2015 Apr 1;89(4):225-8.

Shiu EY, Leung NH, Cowling BJ. Controversy around airborne versus droplet transmission of respiratory viruses: implication for infection prevention. Current opinion in infectious diseases. 2019 Aug 1;32(4):372-9.

Somogyi R, Vesely AE, Azami T, Preiss D, Fisher J, Correia J, Fowler RA. Dispersal of respiratory droplets with open vs closed oxygen delivery masks: implications for the transmission of severe acute respiratory syndrome. Chest. 2004 Mar 1;125(3):1155-7.

Tang JW, Li Y, Eames I, Chan PKS, Ridgway GL. Factors involved in the aerosol transmission of infection and control of ventilation in healthcare premises. J Hosp Infect 2006;64:100-14.

Tellier, R., Li, Y., Cowling, B.J. et al. Recognition of aerosol transmission of infectious agents: a commentary. BMC Infect Dis 19, 101 (2019). https://doi.org/10.1186/s12879-019-3707-y

Thompson KAPappachan JVBennett AM, et al. EASE study consortium. Influenza aerosols in UK hospitals during the H1N1 (2009) pandemic–the risk of aerosol generation during medical procedures. PLoS One. 2013;8:e56278.

Tran K, Cimon K, Severn M, Pessoa-Silva CL, Conly J. Aerosol generating procedures and risk of transmission of acute respiratory infections to healthcare workers: a systematic review. PloS one. 2012;7(4).

World Health Organization. Infection prevention and control during health care when novel coronavirus (‎‎‎ nCoV)‎‎‎ infection is suspected: interim guidance, January 2020. World Health Organization; 2020

Intubation

Cheung JC, Ho LT, Cheng JV, Cham EY, Lam KN. Staff safety during emergency airway management for COVID-19 in Hong Kong. The Lancet Respiratory Medicine. 2020 Feb 24.

Nebulizing a medication

O’Neil CA, Li J, Leavey A, Wang Y, Hink M, Wallace M, Biswas P, Burnham CA, Babcock HM. Characterization of aerosols generated during patient care activities. Clinical Infectious Diseases. 2017 Oct 1.

Amirav I, Newhouse MT. RE: Transmission of Corona Virus by Nebulizer-a serious, underappreciated risk!.

High Flow Nasal Cannula

Hui DS, Chow BK, Lo T, Tsang OT, Ko FW, Ng SS, Gin T, Chan MT. Exhaled air dispersion during high-flow nasal cannula therapy versus CPAP via different masks. European Respiratory Journal. 2019 Apr 1;53(4):1802339.

Leung CCJoynt GMGomersall CD, et al. Comparison of high-flow nasal cannula versus oxygen face mask for environmental bacterial contamination in critically ill pneumonia patients: a randomized controlled crossover trial. J Hosp Infect. 2019;101(1):8487.

Loh NH, Tan Y, Taculod J, Gorospe B, Teope AS, Somani J, Tan AY. The impact of high-flow nasal cannula (HFNC) on coughing distance: implications on its use during the novel coronavirus disease outbreak. Canadian Journal of Anesthesia/Journal canadien d’anesthésie. 2020 Mar 18:1-2.

Non-invasive ventilation

Singh A, Sterk PJ. Noninvasive ventilation and the potential risk of transmission of infection. European Respiratory Journal. 2008 Sep 1;32(3):816-.

Bag-Valve-Mask Ventilation

Chan MT, Chow BK, Lo T, Ko FW, Ng SS, Gin T, Hui DS. Exhaled air dispersion during bag-mask ventilation and sputum suctioning-Implications for infection control. Scientific reports. 2018 Jan 9;8(1):1-8.

Christian MD, Loutfy M, McDonald LC, Martinez KF, Ofner M, Wong T, Wallington T, Gold WL, Mederski B, Green K, Low DE. Possible SARS coronavirus transmission during cardiopulmonary resuscitation. Emerging infectious diseases. 2004 Feb;10(2):287.

Suctioning

Inserting a nasogastric tube

Nitrous oxide

Taking a naso-pharyngeal swab

Examining the throat

Lu D, Wang H, Yu R, Zhao Y. Integrated infection control strategy to minimize nosocomial infection of corona virus disease 2019 among ENT healthcare workers. Journal of Hospital Infection. 2020 Feb 27.

Tang JW, Nicolle AD, Klettner CA, Pantelic J, Wang L, Suhaimi AB, Tan AY, Ong GW, Su R, Sekhar C, Cheong DD. Airflow dynamics of human jets: sneezing and breathing-potential sources of infectious aerosols. PLoS One. 2013;8(4).

Removal of foreign bodies

Surgical spread

Ong J, Cross GB, Dan YY. The prevention of nosocomial SARS-CoV2 transmission in endoscopy: a systematic review of recommendations within gastroenterology to identify best practice. medRxiv. 2020 Jan 1.

Dental spread

Divya R, Senthilnathan KP, Kumar MP, Murugan PS. Evaluation of aerosol and splatter contamination during minor oral surgical procedures. Drug Invention Today. 2019 Sep 1;12(9).

Sabino-Silva R, Jardim AC, Siqueira WL. Coronavirus COVID-19 impacts to dentistry and potential salivary diagnosis. Clinical Oral Investigations. 2020 Feb 20:1-3.