Skip to main content
The Globe and Mail
Support Quality Journalism.
The Globe and Mail
First Access to Latest
Investment News
Collection of curated
e-books and guides
Inform your decisions via
Globe Investor Tools
Just$1.99
per week
for first 24 weeks

Enjoy unlimited digital access
Cancel Anytime
Enjoy Unlimited Digital Access
Get full access to globeandmail.com
Just $1.99per week for the first 24weeks
Just $1.99per week for the first 24weeks
var select={root:".js-sub-pencil",control:".js-sub-pencil-control",open:"o-sub-pencil--open",closed:"o-sub-pencil--closed"},dom={},allowExpand=!0;function pencilInit(o){var e=arguments.length>1&&void 0!==arguments[1]&&arguments[1];select.root=o,dom.root=document.querySelector(select.root),dom.root&&(dom.control=document.querySelector(select.control),dom.control.addEventListener("click",onToggleClicked),setPanelState(e),window.addEventListener("scroll",onWindowScroll),dom.root.removeAttribute("hidden"))}function isPanelOpen(){return dom.root.classList.contains(select.open)}function setPanelState(o){dom.root.classList[o?"add":"remove"](select.open),dom.root.classList[o?"remove":"add"](select.closed),dom.control.setAttribute("aria-expanded",o)}function onToggleClicked(){var l=!isPanelOpen();setPanelState(l)}function onWindowScroll(){window.requestAnimationFrame(function() {var l=isPanelOpen(),n=0===(document.body.scrollTop||document.documentElement.scrollTop);n||l||!allowExpand?n&&l&&(allowExpand=!0,setPanelState(!1)):(allowExpand=!1,setPanelState(!0))});}pencilInit(".js-sub-pencil",!1); // via darwin-bg var slideIndex = 0; carousel(); function carousel() { var i; var x = document.getElementsByClassName("subs_valueprop"); for (i = 0; i < x.length; i++) { x[i].style.display = "none"; } slideIndex++; if (slideIndex> x.length) { slideIndex = 1; } x[slideIndex - 1].style.display = "block"; setTimeout(carousel, 2500); } //

Residents 18 years of age and older who live in COVID-19 hot spots line up for a special vaccination clinic run by Humber River Hospital's mobile team at Downsview Arena in Toronto, April 21, 2021.

CHRIS HELGREN/Reuters

Tom Koch is a medical geographer at the University of British Columbia and the author of Cartographies of Disease and Disease Maps: Epidemics on the Ground.

Thinking of the current surge of COVID-related cases as a new wave of ongoing viral epidemic activity makes it seem like the current increase in cases is just more of the same. The problem is that epidemics are not waves and the new cases are quite different.

What we are experiencing instead is a new epidemic caused by “variants of concern” whose different demographics (younger persons), greater transmissibility and increased virulence mark it as distinct. Understanding that explains a great deal about the surge in hospital admissions and the burden they place on intensive care units in hospitals across the country.

Story continues below advertisement

The pandemic that began in December, 2019, was the great-grandchild of the 2003 SARS virus. That is why it was labelled SARS-CoV-2. It has been proven to be a more robust version of its ancestor. Today’s variants of concern are its offspring – and again more infectious and deadly than the parent.

Think of any movie about Mafia dons who get more conservative as they get older. Their younger lieutenants want to try to expand into new domains and activities. The previous generation is tired and the new, impatient generation takes over. Like those fictional characters, this microbial family acts similarly as it evolves.

India’s COVID-19 variant of interest vs. variant of concern: What does it mean?

In praise of COVID-19 vaccine selfies: Why you should celebrate your shot with a shot

Canada boasts of strong borders while allowing flights from COVID-19 hotspots to land daily

Waves progress, one after another, in a predictable pattern defined by gravity and physics. Epidemics are non-constant events that advance outbreak by outbreak in one population or another. In 2020, the epidemic’s focus was primarily congregate settings of vulnerable adults living in assisted-care facilities. Cruise ships and large gatherings were the perfect medium for epidemic expansion.

In 2021, the new variants have targeted younger people and those working in congregate settings, including factories, warehouses and similar sites. And because it is primarily airborne, the likelihood of contagion in more general public settings is greater. The “kids” are exploring the venues the previous generation tended to overlook.

Mapping the epidemic at the international or national level hides the shotgun-spatter pattern of outbreaks that give an epidemic the appearance of regular spread. It is only when seen at the focussed resolution of the level of a city or local health district that the uneven incidence of infection becomes apparent. There is nothing wave-like here. Each outbreak sparks its own centre of expansion, its own “wave” of bacterial or viral influence.

We’ve used the wave analogy at least since the early 19th century – in early studies of epidemic cholera, for example. While the image worked well at the coarse level of a nationwide lens, it hid the specifics of disease dynamics.

Charts and tables of disease incidence originated in the late 18th-century attempts to correlate disease incidence (yellow fever) with temperature and other climatic variables in both the Caribbean and the United States. Over time, the idea of climatic causation led to increasingly sophisticated charts of weather variables and, for example, cholera cases.

Story continues below advertisement

In looking for a broad pattern of causation, the result gave the impression of a regular expansion and then decline of bacterial events such as cholera. When the charts showed a rising curve that fell and then rose again, the idea of first, second or third waves seemed natural.

As visual tools summarizing long tables of data, these were great and innovative tools. The wave analogy made sense – just as in this pandemic’s charts and maps, COVID-19 cases have looked wave-like, because that’s the way we’ve been taught to summarize this kind of event.

The reality is more complex. For the first time, advances in genomic testing can distinguish between earlier and later epidemics based on different viral generations. Then and now are different. And with data on local outbreaks, the wave image disappears as viral variants address different populations in different cities.

Because the pandemic is not a wave and geographic consistency is not a viral virtue, any given chart, map or table may be misleading. To understand disease incidence requires we see the irregularities. To truly profile these diseases over time, and thus predict their future occurrences, would require an atlas whose maps and data distinguished distinct viral profiles and different at-risk populations over time.

From this perspective, it is easy to understand how health officials appeared to be caught unaware by new viral activity that they should have expected. Were this simply a new wave of the same virus, they might be criticized for their lack of awareness. Given the early stretch of the pandemic, it was easy to assume existing measures would keep the disease under control. Alas, the children of SARS-CoV-2 took a different, unexpected turn.

Analogies are useful tools until they are not. General-population pictures smooth the irregularities that exist at finer resolutions. Seduced by the analogy, we forgot that the regularities of waves do not really serve to describe a disease outbreak – or predict the variants that map distinct health emergencies.

Story continues below advertisement

Keep your Opinions sharp and informed. Get the Opinion newsletter. Sign up today.

Your Globe

Build your personal news feed

  1. Follow topics and authors relevant to your reading interests.
  2. Check your Following feed daily, and never miss an article. Access your Following feed from your account menu at the top right corner of every page.

Follow topics related to this article:

View more suggestions in Following Read more about following topics and authors
Report an error Editorial code of conduct
Due to technical reasons, we have temporarily removed commenting from our articles. We hope to have this fixed soon. Thank you for your patience. If you are looking to give feedback on our new site, please send it along to feedback@globeandmail.com. If you want to write a letter to the editor, please forward to letters@globeandmail.com.

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff. Non-subscribers can read and sort comments but will not be able to engage with them in any way. Click here to subscribe.

If you would like to write a letter to the editor, please forward it to letters@globeandmail.com. Readers can also interact with The Globe on Facebook and Twitter .

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff. Non-subscribers can read and sort comments but will not be able to engage with them in any way. Click here to subscribe.

If you would like to write a letter to the editor, please forward it to letters@globeandmail.com. Readers can also interact with The Globe on Facebook and Twitter .

Welcome to The Globe and Mail’s comment community. This is a space where subscribers can engage with each other and Globe staff.

We aim to create a safe and valuable space for discussion and debate. That means:

  • Treat others as you wish to be treated
  • Criticize ideas, not people
  • Stay on topic
  • Avoid the use of toxic and offensive language
  • Flag bad behaviour

If you do not see your comment posted immediately, it is being reviewed by the moderation team and may appear shortly, generally within an hour.

We aim to have all comments reviewed in a timely manner.

Comments that violate our community guidelines will not be posted.

UPDATED: Read our community guidelines here

Discussion loading ...

To view this site properly, enable cookies in your browser. Read our privacy policy to learn more.
How to enable cookies