A half-hour into his presentation, Dr. Peter Donnelly reached slide 13.

"I want to turn now to perhaps what might be the most disturbing slide in this deck," the president of Public Health Ontario said, speaking evenly. "I think it's important that we all are robustly realistic about the scale of the challenge that we face."

Slide 13 was a simple bar graph indicating that between 3,000 and 15,000 Ontarians might die as a result of the novel coronavirus pandemic over the next 18 to 24 months — a death toll and a time frame that had not previously been publicized.

In the short term, 1,600 Ontarians could be dead by the end of this month. Eighty thousand people may have contracted COVID-19 by then.

Everyone knew (or should have known) before Friday that lives are at stake and that this could be a long, hard struggle. But Canada's most populous province has now provided an official projection of just how tragic and difficult this could be.

Knowledge is safer than ignorance

These numbers are undeniably grim. But knowledge is supposed to be power. And it's possible for Ontarians — and all Canadians — to come away feeling empowered by what Premier Doug Ford's government laid out for them on Friday.

There may be some haggling now over the specifics of the model that Ontario has used, the assumptions that underpin it and the accuracy of the projections it produced. Those projections also will fluctuate as the days go on and new data are added, and special attention will be paid to a projection of how many ICU beds might be needed.

Other provinces are likely to release their own projections in the days ahead. Those projections might show significantly different situations from one province to the next.

There have been demands in recent days for these projections, but there is a case for at least some caution on the part of governments. There is, for instance, already a dispute over the accuracy of the data released by President Donald Trump's administration in the United States.

Keeping trust alive in a climate of fear

The public might lose trust in their elected officials if governments seem not to be transparent. But deeply flawed or confusing projections run the risk of diminishing trust in governments, health officials and experts to an even greater degree — at a moment when maintaining that trust is more important than ever.

As Zeynep Tufekci, the Turkish writer and academic, wrote recently for the Atlantic, there is also a risk of getting bogged down in a debate over whether any given model is "right."

More important is what these projections might tell us about the impact of our own actions.

"The most important function of epidemiological models is as a simulation," Tufekci wrote, "a way to see our potential futures ahead of time, and how that interacts with the choices we make today."

In that respect, the most significant numbers released by Ontario were not the currently projected mortality or infection rates. Beyond those possible outcomes, the Ontario projection looked at two alternative scenarios.

Taking our neighbours' lives in our hands

In one scenario, no measures to reduce the spread of COVID-19 were taken. In that case, Ontario's model projects that 300,000 people would be infected by the end of April and 6,000 people would die.

In other words, by taking action and continuing those actions through the next four weeks — closing schools and businesses, telling people to stay home and practise physical distancing — 4,400 lives might be saved and 220,000 fewer people might be infected.

Ontario Premier Doug Ford pauses during a press briefing at the Ontario Legislature on the pandemic. (Chris Young/The Canadian Press)

If anyone was tempted to believe that the events of the last few weeks were an overreaction to a small threat, they should be thoroughly chastened by such numbers.

Ontario's model also projects what could happen if further measures — stricter closures, more testing — are implemented. In that scenario, the death toll might be reduced to 200 people, saving the lives of another 1,400.

"These numbers tell a story of Ontario's fight against COVID-19," Premier Ford said shortly after the presentation by the province's top medical experts. "But what matters is the ending of our story is still up to us."

What's a life worth? What about 4,000 lives?

The actions of individuals and governments, Ford said, can change these forecasts.

"Over 1,600 people could be dead by the end of April," Ford continued. "Each one could be your brother, your sister, your mother, your father, your grandparents or your friend …

"And we all have to ask ourselves, what is the cost of a life? Is a life worth a picnic in the park? Is a life worth going to the beach? Is a life worth having a few cold ones with your buddies in the basement? The answer is no. None of those things is worth as much as a life. So to everyone in Ontario, we need to listen — we need to listen to what the data tells us."

The greatest value in any set of numbers is in the story they can tell. And the story told on Friday was one of how lives are being saved and how even more lives might be saved in the weeks ahead — and that every resident of Ontario has a part to play in that.

There's still a conversation to be had about how long and how hard this struggle might be. But the stakes, at least, are much harder to ignore now.

"There are 1,600 people out there who need us to do everything we can in the next 30 days to help save them," Ford said.

We hear a lot of war imagery when people talk about the pandemic. But rarely, if ever, have wars come with a clear sense of the number of lives that might be lost, the number of people who might be harmed, or by how much we — citizens, civilians — might lessen that loss and that hurt.

If numbers can reinforce the seriousness of this crisis and persuade us to take action to limit its damage, they will have served their purpose.