swiss cheese slices with a family and covid 19 virus image
Posted in #covid-19

Swiss Cheese Model for COVID-19

The Swiss Cheese Model for COVID 19 is an excellent mental tool to visualize COVID 19 prevention strategies.

First, about the Swiss Cheese Model. As emphasized by James Reason, the model’s creator, it invites us to look at a human error as a consequence, not as the cause. Therefore, according to this line of thinking, error is not a moral problem but a system problem. I have discussed it in the above post.

Swiss Cheese Model for COVID 19

We can apply the Swiss Cheese Model for COVID 19 to visualize and understand COVID 19 prevention strategies. In fact, academics and healthcare practitioners have already applied the model for this purpose. I will discuss their versions here.

Swiss cheese layers with a family and COVID 19 virus
Apply the model for COVID 19

The above image depicts my version. It features the following characteristics.

1. COVID 19 defense layers arranged in levels

The prevention strategies are categorized into three levels: Micro, Meso, and Macro. I bring this group nomenclature from the sociological literature. The following list clarifies what those terms refer to.

  • Micro-level: Individual-level
  • Meso – level: Group or community level
  • Macro-level: Political/policy level

2. The levels in a hierarchical order

The levels are arranged in a hierarchical order. The macro-level layers yield the highest impact. The meso and micro-level layers follow each other respectively. The slices’ increase in size from micro to macro represents it.

3. Each level includes at least two defense layers (slices).

Each level includes at least two layers or strategies (two cheese slices). This is not comprehensive and requires modifications. These layers carry holes of varying sizes and shapes. The holes shift their positions and hence they are dynamic.

  • Micro-level defense layers: Stay at home, face mask, and physical distancing
  • Meso – level defense layers: Community support and lockdowns
  • Macro-level defense layers: Paid sick leave and border control

4. The lower level is dependent upon the adjacent higher level.

Any level cannot withstand by itself; each layer is dependent on its adjacent one. The image depicts it.

The above list of prevention strategies is not complete, and the model deliberately omitted vaccine and testing because its aim is to highlight the relative importance of standard preventive measures. Those interested can include any other measure.

Previous models

Few Swiss Cheese models for COVID 19 exist. The most popular one is the version of Ian Mackay, a virologist from Brisbane, Australia. The New York Times reported it after his version went viral through Twitter. The following is his version.

Ian Mackay’s Twitter on the model

I found a Sinhala version of the Ian Mackay’s version of the Swiss Cheese Model.

File:SwissCheese ver3 SINHALESE.jpg

A Sinhala version of Ian M. Mackay’s adaptation through Wikimedia Commons under the license of CC BY 4.0.

The New Zealand version

Siouxsie Wiles, Associate Professor at the University of Auckland with Toby Morris introduced the following model. It is a very comprehensive one as you can see it. You can read about it in this post of COVID 19 nad Swiss cheese system.


Swiss cheese model for COVID 19 prevention

Source:; New Zealand’s Swiss Cheese model for COVID 19 under the license of CC BY-SA 4.0

Posted in #covid-19 message framing

Do your part – stay apart; more relevant now

This message becomes more relevant now than before with the growing presence of the COVID 19 variants. The new variants are more transmissible; for example, the UK variant is said to be 56 percent more transmissible than the original COVID 19 virus.

What does that mean?

It means if the original one takes 20 days to double the number of us infected, this variant will do it within 10 days. Some epidemiologists predict the numbers can go up by more than 10 fold if the current lockdown restrictions are removed.

Posted in #covid-19 message framing

Message framing effect on vaccine hesitancy-II

In 2018 I explored the message framing effect on measles vaccine hesitancy among the US population. In that post, I highlighted the Hendrix et al. (2014) finding that more parents were modestly persuaded to vaccinate their children when the benefits to the child were emphasized when compared to the standard CDC information. That is about the measles vaccine. And, they explored parents’ intentions to vaccinate their children.

We do not know whether the same holds true for people living in other cultures and other vaccines.

This post is about a study on the influenza vaccine and 222 patients who attended a tertiary hospital in Turkey. These researchers have explored this personal-benefit versus social-benefit dualism with regard to the perceived risk level of the people. In their field experiment, they found the intentions to get vaccinated were higher among those perceived as high-risk when the personal-benefit was emphasized. On other hand, the intentions were higher among those who perceived low-risk when social-benefits were emphasized. In other words, at least for this population further division of the target audience and customizing the message accordingly is more beneficial.

Posted in #covid-19 Risk communication

Is Covid 19 different from the influenza flu?

Even after a year, some are grappling with the same old question: Is Covid 19 different from the seasonal flu?

How do we communicate the risk convincingly to this target audience? Obviously, we need to compare number of deaths due to Covid 19 with the number of deaths due to the seasonal flu. The Centre for Risk and Evidence Communication in the University of Cambridge has done exactly that.

Look at the following graph;

It compares the number of COVID 19 deaths with the deaths from influenza flu and several other common causes. As we can clearly see that the number of Covid deaths sharply increases with age when compared to the deaths from influenza flu. It convincingly debunks the claim that Covid 19 is not different from influenza.

Source: Winton Centre for Risk and Evidence Communication, University of Cambridge

Posted in #covid-19 Risk communication

A face mask is not a substitute for physical distancing

A face mask over your mouth AND nose is not a substitute for physical distancing;

stay at least 6 feet apart from those who don’t live with you.

#WearAMask over youth mouth AND nose in addition to staying at least 6 feet apart from people who don’t live with you and washing your hands often.

Posted in #covid-19 message framing Risk communication

Cover your mouth AND the nose: Massage framing

The CDC has re-framed the face mask message: Cover your mouth AND the nose. This message emphasizes the importance of covering the nose by adding the word, “AND” in-between the mouth and nose.

Posted in #covid-19 Infection control research

Alcohol sanitizers and hand hygiene compliance

Hand hygiene has become nowadays one of the most heard behavioral activities. It is one of the most effective actions we should do to prevent the spread of the COVID 19 virus. Therefore alcohol hand sanitizers are an essential commodity.

The healthcare workers are not an exception.

However, adherence to cleaning hands with 70 percent alcohol hand sanitizers by healthcare workers requires promotion.

Simply, alcohol hand sanitizers should be made accessible at hand whenever necessary, most of the time at bedside of patients in hospitals.

Does alcohol-based hand rub sanitizers, when accessible, improve hand hygiene compliance among healthcare workers?

The answer is yes.

Setting Two ICUs and one general medical ward in a US hospital
Target audienceAll healthcare workers
Study design Six-month observational study
Intervention One sanitizer per 4 bedsides initially and then one per
each bedside was introduced.
Main outcome measure Direct observation of handwashing randomized for the
time of the day and bed location
Findings The compliance rates improved from 19% to 41% with
1 dispenser per 4 beds and from 23% to 48%
with 1 dispenser for each bed.
Conclusion The introduction of sanitizers is associated with higher
rates of handwashing compliance.
Journal referenceApril 10, 2000, JAMA NETWORK;
Accessfree access to the full article

However, the finding is from an observational study.

Posted in #covid-19 Risk communication

How to frame messages in an epidemic – I

Tell the truth; be transparent


The world is now grappling with another global epidemic: the coronavirus, COVID-19.

The risk communication is very critical during epidemics. Its importance is apparent now more than ever.

Providing factually correct messages is necessary but not adequate; the messages need to be framed in ways relevant to the intended audience and persuasive enough to change into the recommended behaviors.

Based on recent past experience with the SARS and Ebola virus types, the World Health Organization (WHO), US CDC, European Union, and almost all countries have developed comprehensive evidence-based guidelines, manuals, training modules, etc.

This post summarizes the relevant sections of these documents while citing those references where relevant.

Steps in framing messages in an epidemic

The US CDC recommends to include the following components when formulating messages with regard to the epidemic irrespective of its mode of delivery, either orally, in writing, or in any other media.

Begin with empathy

  • Acknowledge the target audience’s concerns by saying/writing.
  • Either write or say something similar to this: “we are aware that you are anxious and worried and we care and working to understand their perspective more”.
  • In fact, we need to include contact methods to demonstrate to them that we really care and should promote asking questions.

Identify and explain the threat

  • Mention “what is causing the threat, who is at risk, and what causes someone to be at risk”;
  • “What to do to prevent the harm and to get help if needed”;
  • “Acknowledge uncertainties”;
  • “Do not over-reassure or over-promise”

Explain what is currently known and unknown

  • Provide exact details and timelines
  • Admit what is unknown at the moment saying, “we do not have sufficient information yet and we will inform you as soon as we obtain those details without holding back.
  • Explain what is being done to minimize harm

Explain what actions are being taken and why as well as the actions that are not being taken and why

  • Explain the agencies involved, their roles and responsibilities
  • Share dilemmas, be open with making decisions on imperfect and incomplete information
  • Explain possible undesired consequences, if anticipated
  • Let the media know the assumptions and the possibility of changing recommendations in the future based on new information

Crisis + Emergency Risk Communication (CERC) Wallet Card

The US CDC CERC had produced an extremely useful wallet card that, I believe every professional responsible should carry. Anyone can access to it through this link: