Decreasing your risk of being infected with Covid: Non pharmacological interventions

Profile Picture of Evonne T CurranAs mentioned in our blog published yesterday, along with other Long Covid charities we remain aghast are how little is being done to improve indoor air quality in the UK. In this blog, our infection prevention and control advocate Dr Evonne Curran provides more information about non-pharmaceutical interventions that can be used to reduce the risk of catching covid.

The term non-pharmaceutical intervention (NPI) is used to describe any non-drug or vaccine action deployed to prevent or reduce personal risk of acquisition.  Collectively, NPIs straddle several different sections of the Hierarchy of Controls (HoC) (Figure 1).

Figure 1: Hierarchy of controls

 

Box 1: Additional information about the HOC

  • The HoC was devised for workplace safety but one early Covid-19 lesson was that we needed to consider using control measures outwith outbreak areas and places of work, i.e., as we go about our daily lives.
  • Administrative Controls are about changing the ways of working and so not applicable to non-work environments.
  • The Substitution category is nonsensical for Covid-19 as one cannot replace the virus with a safer one.

For personal risk reduction in the non-healthcare environment an equivalent term would be Risk Reducing Behaviours (RRB).

Despite being devised for workplace safety, the HoC for Covid-19 outwith a care setting is still a useful framework for personal safety incorporating four categories:

  • Elimination
  • Engineering Controls
  • Risk Reducing Behaviours
  • The use of Personal Protective Equipment (PPE)

Rank is still important here. Elimination is always the most effective intervention. If the risk has been eliminated, e.g., non-attendance at an event, there is no need for further action. But we need to assess Covid-19 risks at various times of the day and unfortunately the risks can’t all be eliminated. Further, although PPE is lowest in the HoC rank ordering, when close to a source, using effective respirators as designed, is the best way to negate inhalation risks.

Thus, the HoC provides ranked categories and options to reduce risk; however, whether we behave safely in taking up these options is best explained using the Behaviour Change Wheel (BCW). This theory posits that our behaviour is dependent on our motivation to act safely (awareness of and desire to avoid the consequences), our capability (knowing what and how to do it) and whether opportunities are available to take safe options – including if we have approval to act. Combining these two tools can help us make safe decisions from available options (Figure 2). Thus, our risk of acquisition is dependent on us being able to recognise the risk from (and hopefully in advance of) a given situation and then behaving to reduce (or preferably eliminate) it.

 

Figure 2: Using the BCW to identify what is needed to behave safely and the HoC to identify safe behaviour opportunities

Motivation to act safely can be summarised as: covid is avoidable and it is worth (personally and societally) avoiding. However, for the non-cautions, a little more on motivation…

Motivation for safe behaviours: The infection can be life-threatening and life-changing

Covid is not just a respiratory infection. Yet as a respiratory infection to those with underlying disease or vulnerability it is still significant. About 3000 hospital beds in England per day are occupied by patients whose primary diagnosis is covid. In addition, COVID can result in significant long term consequences to anyone via damage to the heart, the lungs, the immune system, the pancreas, the reproductive system, the gastrointestinal tract, result in cognitive dysfunction, and blood vessel damage including clotting. Long-covid is quality of life-altering that affects both children and adults. It appears the more often you get infected the greater the risk of long covid and significant ill-health.

Motivation for safe behaviours:  Understand transmission risk

SARS-CoV-2 is spread via the air to be either inhaled close to an infectious person, or when the air quality is poor, at a distance. It is more likely to be transmitted close to the source as this is where the virus laden aerosol particles are densest – ergo, when you are more likely to get a greater dose.

  • The more infectious the person, the greater the risk
  • The more people in a confined space, the greater the risk.
  • The more time in a room with poor air, the greater the risk.
  • Some places, e.g., public transport (planes, trains, and buses) is more often poorly ventilated and often presents a higher risk.

Motivation to safe behaviours: Alertness to unrecognisable risks

There will always be unknowns when assessing current covid risk, e.g., we cannot always know:

  • Who is infectious, but asymptomatic?
  • Are we in the presence of a super-spreader?
  • Are the symptomatic people who say they are negative really negative?
  • Are there people present who know they are infectious but omit to communicate their status/take any precautions?
  • Whether any of the people in the meeting room last, were infectious?

Another motivation for me is an ethical one. Answer the question:

How would I feel if I transmitted the virus to someone else who got long-covid and/or died?

I find it helps with motivation to mask!

Some personal assessment of the community risk (and thus your exposure risk when you are in the community) will also help. Data for individual communities will never be available as it was previously; but what is available is your own eyes and ears, e.g.,:

  • How many people do you personally know in your community who are infected now?
  • Where did they think they got infected?
  • How many children / teachers are off sick at the local school?
  • When you are out and about, how many people do you hear coughing?
  • Does the incidence in your community appear to be going up or down?
  • Are people describing infectious symptoms omitting consideration of covid, e.g., a hundred day cough?
  • The old statement ‘there is a lot of it about’ although unquantifiable is useful?
  • What is the event – will there be singing or other activity which presents a greater risk?
  • How many people do you meet each day and what are the odds at least one of the is infectious?

The above will help with a should I stay, or should I go (or at least a should I mask) decision?

Being symptomatic, infectious, or exposed and possibly infectious should also weigh in to our decision-making. The policy should be you-do-everyone – not you-do-you and we all have a responsibility to prevent harm to others.

Engineering Controls

You don’t need to be an engineer to have or use engineering controls, but you do need expert advice and a lot of expert advice is available on various web sites. So don’t take engineering control advice from a retired nurse (me) consider the following from Joey Fox.

How to Stop Airborne Diseases. Understanding how diseases spread… | by Joey Fox | Feb, 2024 | It’s Airborne (itsairborne.com)

This single link includes pages on CO2 monitoring, airborne transmission, and lots more.

One simple engineering control I will advocate is to avoid recycling the air in the car – use fresh air!

Risk Reducing Behaviours and what they can do…

Table 1 details some risk reducing behaviours you can use. It is important to note that:

If you are not infectious (unless you are sneezed on) normal hand hygiene (after toilet use, and before food preparation) is all that is required. Additional surface cleaning is also not required – covid is spread via the air.

If you are infectious – you should not be shaking hands with anyone. You should, as far as is possible, be isolating with separate facilities. Cleaning surfaces after you touched them may help. But the virus exits via breadth and is transmitted via the air.

If someone is infectious and nearby, cough etiquette and hand hygiene is insufficient to prevent transmission. It will still be in the air.

Table 1: Risk reducing behaviours

BehaviourRationale
Outside rather than insideRisk is reduced by dilution of virus in the air, but always note which way the wind is blowing and sit where the wind is not blowing their breadth in your face.

 

Go when least crowdedReduces any potential level of exposure.
Use a CO2 monitorGives a personal alert when levels are high and when additional measures – like removing oneself from the situation, or opening windows, are needed to further.

 

Advocate for workplace / event safetyIf you are booking a venue (or invited to one) ask about their CO2 levels, or how they plan to ventilate the room. Ask about whether they clean the air, whether the windows open and can be opened for the event.

 

Don’t stand so close to me  Don’t get too close to people you meet unexpectedly
Carry and use a respiratorHave ‘always events’ – always wear a mask when for example on public transport: bus, train, plane, shops, or in hospitals… and the rest as ongoing assessment events. I can be in a shop which isn’t crowded and someone will always come up and cough on me when I least expect it. Ergo, I mask in shops!

I eat inside at restaurants very rarely.

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