UPDATE Sept. 18, 2020: The location of a primary government data source used by CBC Montreal for the majority of charts covering Quebec has recently changed. We're working to adjust our charts, but there may be a few days before they are updated.

The summer months in Quebec saw far fewer COVID-19 cases and deaths than in the spring, but as the days grow shorter the threat of a second wave looms.

The Quebec government, which loosened many restrictions over the past months, has turned its focus to maintaining a stable curve in the face of a number of complicating factors, including the return to school, colder weather and increased indoor activity, as well as the coming flu season.

In early September, public health officials introduced a four-tier alert system and Health Minister Christian Dubé said that if infections rise, further public health measures or tighter restrictions will be applied at a regional level.

In light of these developments, we've reviewed and enhanced our set of indicators, most of which will be updated daily, to help you keep track of how the province is coping with the ongoing threat of COVID-19.

Thresholds and effective reproduction

Not long after taking over as health minister in June, Dubé established a numerical line in the sand for new COVID-19 cases: the province should stay below 20 new cases per million inhabitants, averaged over seven days.

That translates to a threshold of 170 new cases per day for Quebec's population of roughly 8.4 million — and the seven-day average crept over that limit in early September. Here's where things stand now:

In late August, Quebec's public health institute, the INSPQ, began publishing a measurement called the effective reproduction number, or Rt, which tracks the number of other people a single infected person is likely to infect.

A value higher than one means infections are increasing; lower than one means they're decreasing. Some experts have said Quebec's data is not comprehensive enough for Rt to be useful, but the chart can be a helpful tool for visualizing whether the disease's spread is getting better or worse. The INSPQ updates these numbers weekly. We explain Rt in more detail here.

Cases, hospitalizations, death: 3 key curves

These are the main figures that Premier François Legault's government has been releasing every day since the start of the pandemic.

Each offers a slightly different perspective of how the outbreak is evolving.

Epidemiologists believe it can take as long as two weeks for symptoms to appear after exposure, so case counts offer a portrait of transmission levels that could be up to two weeks old. Here's a snapshot of where we're at.

Hospitalization and deaths occur well after the onset of symptoms, so these indicators refer to transmission events that are even older.

The hospitalization figures provided by the government are mainly indicators of the provincial health-care system's overall capacity.

At the end of the summer, with hospitalization numbers down considerably from their peak, the Health Ministry says it has 3,000 beds ready if needed — about half as many as were available in the spring, when experiences elsewhere in the world raised fears of hospitals overburdened with patients.

A ministry spokesperson said the government is planning for a second wave and hopes to maintain hospital services like surgery, endoscopy and medical imaging.

Beginning on May 19, Quebec stopped counting certain COVID-19 patients as hospitalized, if they were well enough to be released but still waiting to be transferred to safe institutional care. That caused a sudden artificial decrease in the overall figure.

When looking at deaths, here are two things to keep in mind: Quebec doesn't require a test to declare a death related to COVID-19. It has determined an epidemiological link is sufficient.

Also, the number of deaths announced by the government each day doesn't necessarily refer to deaths over the previous 24 hours.

The chart below shows COVID-19 deaths on the day they occurred, giving a more accurate picture of past trends.

It helps illustrate how devastating the virus was for elderly people in care, be they in the long-term care institutions known by their French initials as CHSLDs, or in private seniors' residences for more autonomous people, known by their French initials as RPAs.

The situation in the regions

Over the summer, a number of restrictions were relaxed, with the size of permitted gatherings increased, and bars, spas and casinos allowed to reopen, joining retail establishments that had been given the green light to resume business in May.

On July 18, a new rule requiring masks be worn in indoor public spaces came into effect.

Over the following weeks, overall cases remained far down from their peak. In late August, a karaoke night at a Quebec City bar led to dozens of infections in the region, and several other regions have seen increases that worry public health officials.

When the regional alert system came online on Sept. 8, four regions — Quebec City, the Eastern Townships, the Outaouais and Laval — were at the yellow, or early warning level. The rest of the province's regions, including Montreal, were at the green, lowest-risk level.

Most public health experts agree that one important tool for keeping the pandemic under control while allowing social and economic activities to take place is testing widely for COVID-19.

Not only does testing make it easier to track the spread of the disease, it results in the isolation of people who are contagious, which helps break chains of transmission.

Since Aug. 1, Quebec has conducted an average of more than 14,000 tests per day.

Another statistic to consider alongside the overall number of tests is the positivity rate, a measure of how many tests out of every 100 conducted come back positive.

If the positivity rate is trending upward, it's an indication there may be a growing number of cases not being detected. It's a sign that more testing is required.

The positivity rate is also an indication of the overall risk of contacting the virus. The World Health Organization recommends positivity rates be five per cent or lower for at least 14 days before authorities lift a public-health restriction.