In my last blog I talked about individual measures that each and everyone can take to stay safe and healthy. Here I will touch on collective measures. Collective measures are those that need to be done together to protect everybody or a specific group of people, such as the elderly and sick. Typically collective measures need the definition of rules within a larger collective, such as a company or by a government. 

Collective measures follow the principle written in the cupola of the Federal Parliament of Switzerland: Unus pro omnibus, omnes pro uno. One for all, all for one. Collective measures work best if they are respected and followed by everybody concerned, and if they take into account both, the needs of the individual and of the community. To achieve maximal compliance, measures need to be well understood, the implementation needs to be discussed and adapted to the circumstances, and the target audience needs to understand that it is necessary and be enabled to follow the rules.

All for one, one for all” written in the central part of the dome of the Federal Palace, the home to the Swiss legislature and executive.

Who should define collective measures?

Typically, associations, companies and governments play an important role in this part of fighting the pandemic. They can issue recommendations, encourage and define measures, and make hard rules.

An association can issue recommendations to its members. These soft rules are important because the members can refer to an agreed-on rule and those not following the rule may even be held liable. For example, a sports-association can recommend minimal measures for players and stadium visitors (e.g. SHV, SFV), a ventilation society can recommend filters and air exchange rates (e.g. REHVA, ASHRAE), or an industrial health and safety society can recommend strategies to keep workplaces safe and healthy (e.g. BOHS, AIHA, IOSH). This list can be extended to all fields of society from retail to culture and arts.

A company should assess the possibility that some of their staff may have contracted the virus, how likely that person is to transfer the virus, and what this can mean for the company. The company must set up rules to protect frail staff, and is well-advised to take measures to ensure business-continuity. In a future blog I will present a tool that can help with these tasks.

A government has a slightly different perspective. Virus-carriers are a certainty in most populations and some of these carriers are super-emitters. So the government must set up rules to reduce the chances that these super-emitters can become super-spreaders, e.g. by limiting the number of people one can meet in an unprotected fashion.

Masks are a key measure (often indoors, in small rooms)

Masks are very effective whenever safe distances cannot be respected, and indoors if the rooms are small and the time together with other people prolonged. Unfortunately, experience shows that only few people wear masks when they are given the choice. Thus, companies and governments should make wearing masks mandatory for all indoor environments with an elevated risk of transfer.

Mask wearing rules that apply only to gatherings of large groups are risky. Every day, a very large number of small groups meet in small rooms, the places with highest risk of airborne transfer. Here, the question is in addition how often do people meet others that come from different groups (e.g. at work the number of meetings involving members from different departments).

Mandating masks is not sufficient. You have to explain why the mask is needed, show how to correctly wear a mask (USE that nose clip! Make it TIGHT AND SNUG on chin and cheeks!), and develop rules that consider the reality of daily life, for example that at one moment or another, people need to eat, drink and socialise.

Amongst all indoor places, the highest risk of airborne transfer is in small rooms. How can this be translated into practice? 

A) Shall we mandate masks in all small rooms? In principle yes, but not always. Let’s look at two examples: 

  1. A small company has a telephone operator in a single office. The operator spends the entire shift alone. If this person is getting sick, not much else will happen. No mask is needed, just a warning on the door, e.g. „maximal 1 person in this room, ventilate room well when changing shift“.
  2. The same person, the same office but this time, the person is also administering the office inventory. Suddenly, the person has become a key social contact.If this person is a super-emitter, all other departments of the company may get infected (mostly because of large „sprayed“ droplets, airborne transfer of viruses is likely only a problem for those staying for a chat). Wearing a mask will be very important and additional measures such as elevated ventilation may be needed.

B) Can we refrain from using masks in large rooms? Not always, but sometimes. Let’s look at two examples:

  1. You run a fine tooling company. The factory floor is a huge hall with many tooling machines, each with only one operator and all several meters apart. Here, masks do not seem necessary, though I would recommend checking the air currents in the room.
  2. The same company, the same floor, but this time, the workers frequently hand over parts to the next worker. As it is too challenging to (control that the workers) always put on a mask before a hand-over, it may be easiest to make masks mandatory (or to change the workflow).

Restaurants remain a tricky situation. While distances can be respected, masks cannot be worn by guests while they are consuming their beverages and food. To control the aerosol risk, the rooms need to be large (probably well > 250 m3), well-ventilated (air exchange rate > 1) and the guest must remain calm (no loud talking, surely no singing) and stay not very long (< 30 minutes). Furthermore, all the staff must wear masks because they stay long time in the room. For other situations, innovative solutions are needed, such as outdoor dining in large tents with roof-openings and walls that leave a gap at the base to create a displacement ventilation. Clearly, too cold temperatures will put limits to such solutions.

Small canteens and coffee break rooms are even trickier. Often, these are small rooms where all the staff of a department gathers for a brief moment of socialisation. They can be key for a good working culture and depriving the staff of this opportunity can be negative for the commitment of the staff to the company. But giving an exception from the mask rule is a recipe for a super-spreading event. A solution could be to still allow these gatherings, but only with masks and to give a few extra minutes of break to go outdoors for drinking the coffee or tea. For lunch breaks, finally, eating in such a small room should not be allowed. Instead, a solution can be to ask staff so eat in shifts in a large hall with a few single tables, if the weather does not allow outdoor eating.

Define priority rules for the novel rapid virus tests 

In the last few weeks, rapid tests that give results within a few minutes and that are very simple to apply got announced, some even approved. These tests work similar to a pregnancy test. Some require only a sputum sample, thus they can be done even by a not medically trained person. Many (but not all) of these tests have a very high specificity and a reasonably good sensitivity. This means that the tests rarely give false positive result (specific), though they may miss those with low viral load (less sensitive). In other words, these tests are likely to identify high emitters, but have some limitations for medical diagnostics.

These new tests are not yet widely available. Shortages can be expected until their production has been ramped up to meet global demands. How can we prioritise and guide the use of these tests?

  1. In my view, priority should be given to situations where the test can decide about life or death. For example to decide about a preventive treatment in a high-risk patient for whom the treatment itself is a risk.
  2. Next, we should consider a contact tracing perspective. Did the person have unprotected encounters with many other people during the last few days? If yes, we need to know if this could be a super-emitter so that all the potential contacts can be put in quarantine asap, before they can further spread the virus.
  3. Next in line should be routine-testing of all those professions where wearing a masks is not an option, such as deaf interpreters, speech therapists, musicians and actors. 

Improve contact tracing and apps 

Contact tracing aims to identify the contacts of a person who got tested positive so that they can go into quarantine. The faster these people are identified, the quicker they can no longer contribute to the spread of the disease. Also, if the contacts are members of a high-risk population, preventive therapies can be started if indicated. So, contact tracing needs to be fast, and it should cover as much of the infective period before the test as possible. There are many situations where either a case does not remember what he or she did two days ago, or where the contacts are people whom the case does not know (e.g. other people in a train).

Contact tracing apps such as the Swiss COVID App alert you when you spent a certain time near a positively tested person while infectious. In which cases is this useful, when not?

  • If you are at a place where no masks are worn (e.g. an outdoor gathering) and you discuss with several people, it can happen that you forget to keep distance. Here, you clearly have an elevated risk of spray transfer. The app will record this encounter.
  • If you travel by train, you will be wearing a mask. I personally always wear an FFP2-mask without valve, and I go to another carriage if a person without mask decides to sit near me, especially if the person talks loudly. So for me, sitting next to an infected person is only a small risk. However, if you like to „drink“ a coffee for an entire train ride (as an excuse for not wearing a mask), your risk can be very high, especially if the positively tested person also wears no mask. In both cases, the app will record the encounter.
  • If you share all day a small office with an infected person with the tables several meters apart, your airborne transfer risk is elevated to very high, depending on whether both wear a mask or not and the viral load of the infected one. Unfortunately, the app will NOT record this encounter.
  • If you eat in a small restaurant with all tables at recommended distances and the infected guest at another table talks vividly, you can have a very high airborne transfer risk because you are not wearing a mask. But the app will NOT record this encounter.

These examples show that to make a reasonable risk appraisal, we need the context and not just information about the fact that we were near an infected person; and we need to improve the app to sound the alarm also when aerosols are likely a problem.

The app is designed for maximal personal data protection. It saves only the randomly generated ID of each „close contact“. This is very unfortunate because we also need the contextual information, which we could derive it we knew the date, time and location of the encounter. To make the app truly useful, it is important to allow it to record also time and location and not just a contact code. Another wish would be to record also prolonged presence in the „far-field“ (e.g. longer than 30 minutes at less than 10 meters distance), such as time in a shared office or in a (small) restaurant. All this data can stay encrypted on the device to respect data protection concerns. There will be occasions where you will be able to tell who was the infected person. But this, in my view, is an acceptable breach of personal data protection as it serves to protect the life of many people. Finally, the app should also alarm you when you were near an infected person who had a very high viral load (=a potential super-spreader). This could be an optional information to be transmitted via the contact tracing app servers if a positively tested person agreed to share this data.

SCOEH researchers also have many other ideas related to contact-tracing. For example how to support contact tracing by better identifying super-spreaders. Or how to develop a questionnaire, to be filled out by every person showing up for a Corona-test, to better help understand the circumstances of infection. We currently try to find collaborators and funding.


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