What we can learn from the evolution of guidance during the COVID-19 pandemic

To be impactful, public health policy must be dynamic and iterative. While public health professionals understand the need to continuously update measures based on evidence and context, this nuance is often lost on a general public that tends to see it as being fickle and backtracking.

Historically, public health measures have often arisen during disasters such as outbreaks, pandemics and wars when critical concepts developed and evolved as the scientific and social information available expanded.

Public health policies often have been viewed as controversial when first introduced. We have seen this occur for a variety of issues, whether it be curbing the spread of infectious diseases or the evolution of concepts of hygiene and sanitation. In addition, public health is also intricately tangled with political complexities and ideologies. Indeed, the implementation of almost every public health measure requires political decision-making, use of government infrastructure and funds from taxation. As Rudolf Virchow, the founder of social medicine astutely stated: “Medicine is a social science, and politics is nothing but medicine at a larger scale.” It is therefore unsurprising that the introduction of any public health measures frequently results in significant pushback.

The only absolute in science is that there are no absolutes. Throughout the pandemic, recommendations have changed based on new data. For the public, this may come across as flip-flopping, but in actuality, it is simply that we are making the best decisions possible in the current context. As said by Ross Upshur:

“Research evidence is neither eternal truth nor a constant (outside of certain basic biologic laws). This is a major barrier to both the public and professional dissemination of research evidence as there seems to be a dissonance between the actual evolution of scientific knowledge and the public’s preconceptions about what medical science can provide.

The scientific uncertainty was not incorporated into these recommendations.

Masking is a great example of how public health guidance can evolve significantly. In the early days of the COVID-19 pandemic, masking by the general public was not recommended due to various reasons –  a limited stock of medical-grade masks for health-care providers; concern that masking would make people take risks such as participating in large indoor gatherings; worries they might not mask properly and/or put themselves at a higher risk of infection by continuously fidgeting with the mask; and that SARS-CoV-2 was thought to be predominantly transmitted via fomites and big droplets. While the scientific rationale was inconclusive or weak, the recommendation was clear – masks should not be worn by those not working in health care. The uncertainty due to limited scientific evidence was not incorporated into these recommendations. In addition, there was considerable variation within the scientific community as not all moved at the same pace with emerging data nor did they interpret the data in the same manner. 

Over time, additional information became available, particularly around virus transmission via smaller droplets and aerosols through expiratory activities such as coughing or sneezing. Data on the effectiveness of masks significantly improved and public health guidance shifted from no masking to cloth or fabric masks to recommending the use of N95 respirators or similar masks with proper filtration and fit. From the public’s point of view, this seemed like a complete reversal in recommendations, and without adequate communication explaining the rationale behind these changes. Unsurprisingly, the swinging of the pendulum caused confusion; we still have opponents to masking measures.

Take another situation. When AstraZeneca, a viral vector vaccine, was approved, the National Advisory Committee on Immunizations (NACI) recommended it be used only for adults aged 64 and younger. This was because the original clinical trial had a smaller number of participants in the 65+ age group and a reliable estimate of vaccine efficacy was not possible Within a few weeks, rare blood clots were identified in Europe. While the risk of these blood clots – Vaccine Induced Immune Thrombotic Thrombocytopenia (VIIT) – was small, the blood clots themselves were severe and associated with high rates of mortality, prompting NACI to recommend suspending the use of AstraZeneca for those under 55. Within mere weeks, we went from AstraZeneca not being recommended in the 65+ age group to it being recommended for use only in the 55+ age group.

Simultaneously, Health Canada released a contradictory statement saying that the health agency conducted an analysis, and they consider the vaccine safe to be used for anyone above the age of 18. The message to the public unequivocally was to get vaccinated with the first vaccine available to them. Many physicians were upset with NACI’s recommendations and spoke in favour of using AstraZeneca despite the small but real risk of VITT. However, they erroneously compared these risks to those from blood clots via hormonal contraption, which is a very different and much easier to treat than VITT, making it an inaccurate comparison.

Understandably, these incidents caused mass confusion and destroyed confidence and trust. Throughout, there was a dearth of communication explaining the rationale behind these changes that were, in fact, based on evolving evidence.

For any vaccine or medication, benefits must outweigh risks. There is no such thing as zero risk; we all take calculated risks daily. Early reports of VITT from Europe had pegged incidence at extremely low at around one in 250,000 doses. Over time, additional information was available since VITT can take a few weeks to manifest and be diagnosed. Eventually, Ontario Science Table data showed risk as high as one in 26,000 depending on the jurisdiction and the demographics of the population receiving this vaccine.

The evidence was not clearly shared with the public and much of the information was politicized with clear partisan divides.

However, when AstraZeneca was first rolled out, we were heading into a period in which the Delta variant was soaring and availability of mRNA vaccines was severely limited and/or delayed. This necessitated the recommendation of being vaccinated as soon as possible. As the information around VITT began to unfold and our Delta wave began to recede, our mRNA vaccine availability improved drastically with many millions of doses making their way into the country.

Given that the wait for an mRNA vaccine was now negligible and that the risk of VITT, while low, was much higher than originally anticipated, NACI subsequently preferentially recommended mRNA vaccines. The provinces followed suit and the use of AstraZeneca for first doses was suspended.

But where did this leave people who had done the right thing and received the first vaccine available to them, which happened to be AstraZeneca? We did not at that time have sufficient information on heterologous prime-boost regimens, thereby leaving those who received AstraZeneca as their first dose uncertain on what to do for their second dose. Unfortunately, the evidence was not clearly shared with the public and much of the information was politicized with clear partisan divides. It was a complete failure of public health communication once again, resulting in chaos, panic and dwindling trust in health institutions and governments.

What was missing during this period was clear communication that was transparent about the uncertainty while building confidence and offering explicit advice. The mixed, ambiguous messaging further fuelled vaccine hesitancy, resulting in the public turning to non-credible sources. NACI’s role – to provide recommendations to the provinces – is done on a fully volunteer basis. It is not designed to provide communication to the public, and in its quest to fill the communication gap, it made matters worse.

Communication of a public health policy is as important as the actual policy. How messages are framed has a significant impact on the public, and policy only works if there is public buy-in. There is data to show that conflicting and contradictory guidance erodes trust over time; that ineffective communication of uncertainty damages credibility; and that uncertainty is politicized to impact public attitude. A sure way to undermine public trust in science and public health institutions is the combination of mixed messaging, misinformation and political interference. Indeed, even during the 1918 Influenza pandemic, there was considerable pushback on public health measures such as masking, lockdowns and vaccination due to a combination of similar factors.

A key lesson from the COVID-19 pandemic must be the importance of effective, transparent and reliable communication that builds uncertainty into its guidance such that when it evolves, it does not breed distrust. The future of public health depends on it.

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1 Comment
  • rickk says:

    All the experts were wrong – wrong about locking down, masks, ‘vaccinating’ (more like inoculating) everyone instead of those at high risk of bad outcomes. All the experts are wrong about the total safety of the inoculations, wrong about ‘if you get the inoculation, you won’t get covid’, wrong about ‘if you get the inoculation and get covid, you won’t spread covid’, wrong about ‘no real lasting protection’ despite recovering from covid, wrong about boosting 1x, 2x, 3x in that it will protect you. But when the NIH/CDC changed the definition of vaccine and vaccination to fit the narrative – then those not afflicted with cognitive dissonance understood that the reactions to this pandemic have been a grand ruse.


Sabina Vohra-Miller


Sabina Vohra-Miller is the co-founder of the Toronto-based Vohra Miller Foundation, which aims to improve the health of the planet and its people.

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