Monty Python and the Science of Safe Singing

Monty Python and the Science of Safe Singing

Commentary by Tim Fisher

Two powerful ideas are colliding in the COVID world which may shed valuable light on both these crucial matters to society’s benefit. The first relates to the importance of singing and the dangers it may cause in the midst of a pandemic. The second is the value of science and the rampant scepticism that has emerged as to the value of the scientific approach.

To set the scene it is valuable to introduce the seminal work of Monty Python to illustrate how easily our understanding can be waylaid. Click on the video to reveal the classic Python lesson on logical thinking.

Bedevere uses the Law of Syllogism (i.e., the Law of Transitivity) repeatedly in his argument. If one relates to a second, which relates to a third, then the first is related to the third. His findings aren’t peer reviewed. His logic and his method are flawed.
 

Enter community singing, stage right. Singers have been advised that COVID-19 can be transmitted in the air well before the WHO were persuaded of this last month. Since March there have been reports of mass infection events in choir rehearsals in several countries as the world started to go into the first lock-down. A conclusion drawn in these reports is that singing is therefore more dangerous in a COVID-19 world than other activities.  

The line of reasoning presented is that speaking creates more aerosols than breathing, loud speaking creates more aerosols than quiet speaking. Singing is louder than loud speaking. Therefore singing must create more aerosols than loud speaking making it more dangerous as an infection source. Thank you Sir Bedevere.

In fact singing, due to the breath control and occlusion of airflow through the vocal chords, produces very little airflow from the mouth. The method of generating sound in singing through resonance rather than air flow means that the Law of Syllogism does not hold here. The image conjured in the learned articles of “geysers” of aerosols flowing for many metres from every singer is simply incorrect and yet journalists, and occasionally experts in other fields, have been drawn to these conclusions due to a logical error.

This is not to say that singing is without risk.  People vulnerable to complications from COVID-19 should make informed decisions about all activities that they undertake in a pandemic and singing in groups is an activity that may lead to risk of infection in the event of community transmission of the virus.  The concern is that singing is being unreasonably targeted through insufficient knowledge and flawed logic.

Other experts are being more scientific and conducting experiments to measure how many aerosols are generated when people sing. This must be good news because when these results are in we will not be inferring knowledge but instead will have hard facts…..right? Probably not. If our goal is to understand how to mitigate the risks of contracting COVID-19 from singing rehearsals and performances then we need a lot more facts if sensible conclusions are to be drawn. An incomplete picture, how many aerosols are produced by a singer, does not enable a risk mitigation to be devised unless we also know:

  • what is the equivalent risk of conducting other acceptable activities within a pandemic?
  • How many aerosols are produced in a wide range of other activities such that the relative risk can be assessed?
  • How much viral load is required to become infected? How many aerosol particles from an infected person contain viable virus? How many virus containing aerosols must be inhaled or absorbed through the mucous membranes to cause infection?
  • How long is an aerosol particle viable? Is evaporation a significant variable? What is the effectiveness of various barriers, masks and baffles such that mitigations in addition to physical distancing can be quantified?
  • What is the impact of the volume of the room and the type and quality of ventilation? What is the impact of singing outside?

Fundamentally, the initial science being directed at the question of whether singing can be conducted with an acceptable level of risk during a pandemic is unequal to the task. And rightly so. There are much more pressing questions that science could be tackling in a comprehensive manner at this point, like why health workers with approved PPE are able to catch COVID-19 at such high rates in Victoria more than 4 months into a worldwide pandemic where data must be available as to what works and what doesn’t in the healthcare setting.

However, the lack of scientific testing, experimentation and conclusive results around the question of the risks posed by singing should not be seen as an opportunity to exercise “an abundance of caution” and ban this fundamentally human and social activity as has been suggested in a number of opinion pieces since March. If we accept that we must take risks to survive in a pandemic then we must make a judgement as to what risks are worth taking.

Singing is as beneficial as sport and is practiced by roughly as many people as participate in organised community sporting activity. It is probably less aerobically energetic than most sporting activities and much more controlled than a rugby scrum, a football tackle not to mention a trip to the supermarket or the shopping centre.

As expressed by leading British composers, musicians and choral directors in an open letter to the Guardian newspaper last month:

“Singing in a choir is not only about communality, social cohesion and

harmony; for many it is an essential source of emotional wellbeing and

positive mental health. Moreover it is a powerful expression of our culture

and humanity, and it cannot be allowed to fade away.”

We allow science to fall into disrepute when we fail to understand its limitations. We allow our communities to fall into fear and recrimination when we seek absolute safety in the face of a pandemic. We allow our lives to become meaningless if we don’t strive to preserve the cultural and artistic fabric that enriches us.

If data emerges that singing represents an infection risk greater than going to a restaurant, interacting with hundreds of people at a supermarket, sweating next to dozens of people at a gym, socialising at a noisy pub or joining your extended family at a dinner table then let’s find ways for people who have low vulnerability to complications from COVID-19 to do so at a lesser risk rather than opting to ban it outright……unless it is necessary to ban all of these things outright in order to control community transmission. Singing is as important to our wellbeing as any of these things so let’s find a way.

If the data that emerges isn’t sufficient to demonstrate or quantify that risk then let’s not act on it as if it does.

Community Choirs and COVID

WA Community Choirs and COVID

A discussion paper with resources

Colleen Dixon and Tim Fisher

SongFest Inc is a not for profit organisation with the aim of promoting community singing in Western Australia. To date, SongFest’s most visible work has been in organising or facilitating festivals for singing groups.

Suddenly, and quite unexpectedly, the COVID pandemic seriously challenges community singing in WA, as everywhere. The aim of this document is to share information relevant to directors and managers of choirs to assess how they could resume live rehearsals. It also presents ideas that may assist choir managers to decide whether, when and how to resume rehearsals. The discussion will be ongoing as the virus’ spread is managed in WA and as more information comes to light about the virus in general and its relationship to singing.

This document is not intended as scientific or medical advice. We cannot find any studies that are directly related to the spread of COVID by group singing activities. Consequently there is no certainty or assurance of safety that can be given to participants in group singing.  In fact, quite the opposite.  Singing, like most activities, represents a risk of virus spread.

Does that mean that community singing needs to come to a halt in WA until a vaccine is developed? Singers who are vulnerable to complications from COVID infection may well decide so. Others may decide to sing.  Singers can evaluate risks from an informed position and act to maximise their chances of avoiding infection and infecting others when they do rehearse.

 

Higher risk people

Singers who fall within the high-risk categories for complications with COVID need to decide if they should undertake any high-risk contact activities, including singing.  Group rehearsals in any circumstances will entail some level of risk. Details of high-risk people are detailed in the link below for your information.

https://www.health.gov.au/news/health-alerts/novel-coronavirus-2019-ncov-health-alert/advice-for-people-at-risk-of-coronavirus-covid-19/coronavirus-covid-19-advice-for-older-people

 

Risks that may be associated with singing rehearsals and events and the basis for this association

We note the concern regarding group singing based upon a number of clusters identified in several countries where singing groups, rehearsing without precautions or with partial precautions, experienced very high levels of cross-infection attributed to a single rehearsal. The CDC report into the Washington choir cluster can be read here https://www.cdc.gov/mmwr/volumes/69/wr/mm6919e6.htm

This has led health authorities to believe that some aspect of the “normal” singing can make singers “super spreaders”. The exact mechanism is not known. It may be a combination of:

  • greater proportion of droplets and aerosols (which can contain the virus) by singing compared to talking
  • Larger numbers of people generating thermal mixing of the air in the rehearsal space which spread the aerosols throughout the space to a greater extent
  • Aspects of the volume of the rehearsal space, the extent to which singers are facing each other, the amount of natural ventilation, use of air conditioning recirculating air and impact of overhead fans
  • The age of the singers
  • The relatively long period of contact across a rehearsal
  • Socialisation and refreshments associated with tea breaks

The WA Health Department have been approached directly by ANCA regarding the health risks of singing.  The advice received from Dr Revle Bangor-Jones Coordinator – (WA) Public Health Emergency Operation Centre was;

“Phase 3 of the COVID-19 WA roadmap allows for indoor and outdoor gatherings of up to 100 people at any one time, per single undivided space, and applying the revised two square metre per person capacity rule. School choirs in WA have recommenced.

Everyone is encouraged to continue to practice physical distancing and good personal hygiene and minimise the use of any shared equipment. Shared equipment should be cleaned between use.”

This indicates that singing isn’t considered by WA Public Health to be special as an activity at this stage.

Other studies have been conducted into the viability of the virus on various surfaces and environments. The first here: https://www.nejm.org/doi/full/10.1056/NEJMc2004973

The second has not been published but was reported in a govt briefing in April. https://www.nytimes.com/2020/04/24/health/coronavirus-summer-ultraviolet-light.html

Relevant data includes:

Research on the longevity of the virus on surfaces and in the air indicates that dark, cool, dry environments maximise the viability of the virus while exposure to sunlight and humidity dramatically reduces the half-life of the virus. The use of cleaning agents which destroy the fatty layer surrounding the virus are the most effective.

The use of masks or other PPE to prevent spread may also play a part in a mitigation strategy. The WHO advice can be viewed here https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks

The effectiveness of masks is impaired by the duration of use (30 minutes is considered an upper bound beyond which the buildup of moisture on the mask enables aerosols to be generated through the mask), touching the mask with hands, incorrect removal and application (by the straps, not the fabric) and by the volume of air generated by the user.

 

Risk Mitigation

Groups with singers who are prepared to accept the level of risk associated with group singing will want to act to maximise the protection of their close contacts should their singing activity ultimately result in an infection.

A key tool to mitigating the risk of infection of close contacts of singers is to utilise the COVID Safe App or for choirs to keep a record of all rehearsal attendees. In Australia we have bought time through our national lockdown to enable us to prepare and boost our testing and contact tracing capability. Our ability to gather together with reduced social distancing and open our community to the rest of the country and to the world, depends on rapid identification and isolation of new infections and isolation of all close contacts. This process will be greatly enhanced by the adoption of the app and singers can lead the way to assist widespread acceptance of our “high-risk” activity.

Factors which may help reduce infection risk during rehearsal may include:

  • Higher spacing between singers.
  • Participant numbers – other mitigation strategies can be enhanced as numbers increase. For instance, making some rehearsals sectional only would limit the number of times the whole group comes together.
  • Outdoor rehearsals — these offer the benefits of natural ventilation and sunshine, which has been shown to reduce the viral load.
  • Shorter Singing aspects of the rehearsal could be focused.
  • Separate singing and socialising: Non-singing aspects of the rehearsal could be conducted in a different space. Groups can avoid conducting refreshments in the rehearsal space. Practice high levels of personal hygiene around all sharing of food, drink and utensils.
  • Practice hand hygiene before and after singing phases of the rehearsal.
  • Chairs can be set out, stacked and cleaned by a small number of people practicing social distancing rather than having everybody congregating and milling around.
  • Singers who are at high risk of serious outcomes with COVID face a difficult period in terms of live singing.  Consider streaming the group’s rehearsals and having high risk members participate on a screen in the rehearsal space.

Some final thoughts: Western Australian conditions

At the time of writing there is little risk in live rehearsals because in WA we have almost no COVID community transmission. However, this is a marathon, not a sprint. The virus may represent a health risk for years to come.  A plan to keep singing when modest levels of community transmission are identified is a key goal that choirs should consider. Do you stop as soon as community transmission is detected or does your group bring in some additional mitigation measures and keep singing together?

Other choir organisations around the world are still seeing significant community transmission and may still be some way from getting back to live rehearsals. Can we develop approaches here which will help choirs in other countries get back to singing together?

Aerosol Impact studies

Aerosol Impact Studies

 

“RISK ASSESSMENT OF A CORONAVIRUS INFECTION IN THE FIELD OF MUSIC”             Spahn/Richter

The most relevant and comprehensive report we have seen so far comes from German researchers who are explicitly seeking to develop risk mitigation approaches for singing and instrument players of all types. While it is clear that key elements of the puzzle are still unknown this report gives a lot of considered proposals which may resonate with your choir members.

Generally, large numbers of people in small, indoor spaces are correlated with significant infection risk. These authors strongly favour outdoor musical activity. Provided the system is utilising 100% fresh air these authors consider ducted air conditioning systems to be the next best option.

 

“Cluster of Coronavirus Disease Associated with Fitness Dance Classes, South Korea”    Sukbin Jang, Si Hyun Han, and Ji-Young Rhee

Research into a cluster of cases in South Korea relating to dance aerobic exercise sessions generates some interesting data that may be relevant to higher aerobic activities compared to talking. Researchers concluded that factors that may have contributed to the high levels of transmission between the infected instructors and their class members was relatively large numbers of people (classes of 20 had much higher infection rates while classes of 5 had none) in a relatively small room (60m2) undertaking high intensity activity. An infected instructor who taught Pilates and yoga in the same room (with a class size of 8) spread the virus to none of the class. The moist, warm environment of a sports complex coupled with turbulent air flow was also hypothesised as a contributing factor.

 

Comparative dynamic aerosol efficiencies of three emergent coronaviruses”    Fears, A.C. et al, Tulane School of Medicine

The ability of the COVID-19 virus to remain viable in aerosol form may be more significant than its SARS and MERS predecessors. In an, as yet non-peer reviewed comparative study, researchers concluded that:

“The comparison of short-term aerosol efficiencies of three emergent coronaviruses showed SARS-CoV-2 is on par with or exceeding the efficiency estimates of SARS-CoV and MERS-CoV. Some efficiency determinations for SARS-CoV-2 ranged to -5.5log10, a full log difference compared to MERS-CoV. The fact that higher efficiencies trended across independent laboratories strengthens this observation. These data suggest that SARS-CoV-2 generally maintains infectivity when airborne over short distances, in contrast to either comparator betacoronavirus. Results of the aerosol suspension experiments suggest that SARS-CoV-2 is persistent over longer periods of time than would be expected when generated as a highly respirable particle (2 μm MMAD). This is remarkable, as there would be an expected decay and loss in the infectious fraction of airborne virus based on prior susceptibility studies with other relatively environmentally hardy viruses like Monkeypox . A recent study , showing only a slight reduction of infectivity in aerosol suspensions with approximately similar particle sizes, were suggestive of the minimal effects on SARS-CoV-2 infectivity observed in these results.

Collectively, this preliminary dataset on the aerosol efficiency and persistence of SARS- CoV-2 suggest that this virus is remarkably resilient in aerosol form, even when aged for over 12 hours, and reinforces the conclusions reached in earlier studies of aerosol fitness by others . Aerosol transmission of SARS-CoV-2, whether through direct respiratory droplet transfer or fomite generation, may in fact be a more important exposure transmission pathway than previously considered . Our approach of quantitative measurement of infectivity of viral airborne efficiency complemented by qualitative assessment of virion morphology leads us to conclude that SARS-CoV-2 is viable as an airborne pathogen. Humans produce aerosols continuously through normal respiration . Production of aerosols increases during respiratory illnesses,and even during louder-than-normal oration . A fraction of naturally-generated aerosols fall within the size distribution used in our experimental studies (<5 μm), thus leading us to the conclusion that individuals infected with SARS-CoV-2 have the capacity to produce viral bioaerosols that may remain infectious over long periods of time after production via human shedding and airborne transport. Accordingly, our study results provide a basis for a broader recognition of the unique aerobiology of SARS-CoV-2, which may ultimately lead to tractable solutions and prevention interventions in the ongoing pandemic.”

 

“Testing the Efficacy of Homemade Masks Would They Protect in an Influenza Pandemic”   A. Davies et al

The use of PPE to interrupt transmission of the virus is also an area with a lot of information but little clear data. The full report must be subscribed to but the abstract on a Cambridge University study into the effectiveness of face masks made from non-medical fabric (t shirt fabric for the most part) can be seen here.

  • They are found to be about a third as effective as medical grade masks but a considerable improvement on nothing at all.
  • Other research found that some readily available fabrics that were more effective than surgical masks but not as effective as N95 masks. An extract from that source summarises results as follows:
  • “To test various masks and fabrics, the team pumped air through both types of face coverings.
  • “Our instruments could read down to 0.3 microns, which is about the size of a big virus,” Segal said.
  • Regular surgical masks filtered out 62 percent to 65 percent of particles. For comparison, N95 masks filter 95 percent of those particles.
  • But the fabrics led to a variety of results. One piece of cloth filtered just 1 percent of particles, rendering it virtually useless, while others were found to perform even better than the surgical masks.
  • “We had some that performed at 79 percent,” Segal told NBC News.
  • The best masks were constructed of two layers of heavyweight “quilters cotton” with a thread count of at least 180, and had thicker and tighter weave.”

Respiratory virus shedding in exhaled breath and efficacy of face masks           Nancy H. L. Leung et al

This paper published in Nature Medicine studied seasonal human coronaviruses, influenza viruses and rhinoviruses in exhaled breath and coughs of children and adults with acute respiratory illness.  Tests were done with and without surgical type masks.   The paper showed much better results for using masks against coronaviruses compared to influenza viruses.  The following is an excerpt from the discussion;

“Our findings indicate that surgical masks can efficaciously reduce the emission of influenza virus particles into the environment in respiratory droplets, but not in aerosols….. We also demonstrated the efficacy of surgical masks to reduce coronavirus detection and viral copies in large respiratory droplets and in aerosols. This has important implications for control of COVID-19, suggesting that surgical face masks could be used by ill people to reduce onward transmission.”