This is not a bright moment in Canada's fight against the novel coronavirus.

Nationally, the seven-day average of new COVID-19 diagnoses is as high as it's ever been.

On Friday, Ontario announced its highest single-day total of new cases to date. On Saturday, it was Quebec's turn. In Manitoba, nearly two-thirds of all known cases have been logged in the past month.

Even some parts of the country less affected by the pandemic are showing a resurgence in virus activity. Prince Edward Island has recorded 13 cases of COVID-19 in the past 32 days – a worrying number when compared to the 16 cases detected on the island in the previous 127 days.

All of this lends weight to what politicians and public health authorities have been saying since long before the increases began: The virus will not disappear on its own, and Canadians' individual actions may well determine whether the second wave is manageable or uncontrollable.

There's a message of hope buried in that warning. But there's also the reality that many important factors are beyond the control of individual Canadians.

Here are seven reasons why the recent increases in COVID-19 activity in Canada may only be the tip of the iceberg.

HOSPITALIZATIONS ARE RISING

When daily case counts started to trend upward, there was a persistent chorus arguing that it wasn't as bad as it seemed, because hospitalization numbers weren't moving with them.

However, hospitalizations are known to be a lag indicator. When case counts increase, it is a week or more before hospitalizations move in the same direction.

For most of the summer, the number of Canadian COVID-19 patients in hospital was actually decreasing day by day. That's not the case anymore. There hasn't been a single day with a declining hospitalization number since Sept. 16. Over the past two weeks, most days have brought an increase of at least 20 patients.

The number of hospitalizations in Ontario and Quebec has tripled in recent weeks, according to The Canadian Press, while British Columbia's hospitalization number quadrupled in September.

"We certainly are getting a gradual and steady increase in the number of people who are seeking hospital care," Dr. Matthew Oughton, an infectious diseases specialist based at the Jewish General Hospital in Montreal, told CTV News Channel on Sunday.

Many experts believe the rising hospitalization numbers are a sign that the virus is again being spread to seniors and other vulnerable groups, after a summer during which it was most active in young adults – a demographic less likely to suffer severe symptoms.

CASES ARE A LAG INDICATOR TOO

The number of cases announced on any given day does not reflect the virus transmission situation on that day.

Accepted wisdom among epidemiologists is that it takes up to two weeks before changes in societal behaviour are reflected in the daily case counts.

That means that measures taken during the past week in response to the recent high numbers – think of Quebec placing its largest cities into 'red zones' and Ontario reducing the number of people allowed at gatherings – will not be reflected in the daily totals for another week or so.

"We may well see the numbers at least continue, if not climb, for another week before we even begin to see a bit of a slowdown," Oughton said.

If the numbers continue to climb, governments may decide to impose harsher measures – but it will be another two weeks or so before those decisions have any effect on the daily numbers.

THE HEALTH-CARE SYSTEM MAY NOT BE READY

When most provinces enacted lockdown-like measures in the spring, the stated reason was that they were necessary to prevent hospitals from being overwhelmed by sudden influxes of large numbers of COVID-19 patients.

Now, case counts are back where they were at the height of the first wave and hospitalizations are also increasing – but governments clearly do not want to order businesses to close their doors once again.

As a result, concerns have been voiced by the medical community that there could be a fast ramp-up in the number of patients seeking COVID-19 care – and that the health-care sector may not be prepared for this. The Ontario Hospital Association recently wrote the province asking for a return to lockdown in the hardest-hit areas.

"Our health-care system is incredibly precarious at the best of times," Dr. Ilan Schwartz, an assistant professor in infectious diseases as the University of Alberta," said Sunday on CTV News Channel.

Most health-care professionals have stopped short asking for lockdowns to be re-enacted, despite clear worries about what may be ahead. A survey by the Canadian Medical Association found that more than two-thirds of community-based doctors are worried they won't be able to obtain enough personal protective equipment to keep them and their patients safe.

Hard-hit Ontario has attempted to stem these fears, announcing last week that it plans to hire 1,400 nurses to work at hospitals and long-term care homes. However, it is not known how soon all those positions can be filled.

TESTING AND TRACING BACKLOGS

Wearing a mask is a great way to help reduce the spead of COVID-19, while washing your handsand physical distancing is a great way of protecting yourself.

But getting every single person on-board with all of those actions all of the time is virtually impossible. That's where governments need to pick up the slack – and it has become clear through the pandemic that widespread testing, rapid processing of test results, and thorough contact tracing are the best way they can do that.

It may be a problem, then, that several provinces are finding it difficult to pull off effective testing and tracing.

Alberta recently introduced new testing criteria in an attempt to prioritize the most important potential cases. Testing capacity in Manitoba is low enough that some Winnipeggers have reported waiting in line for four hours or more, and others have driven an hour outside the city to get tested.

The worst situation of all may well be in Ontario, where the testing backlog routinely numbers in the tens of thousands, leaving some unable to get results for up to a week.

That creates another problem. The longer it takes for a positive test result to be known, the less effective contact tracing is.

Toronto Public Health, the province's largest public health unit, announced Friday that it is now only performing contact tracing for the highest-risk scenarios – a far cry from the testing of all cases that helped some countries in other parts of the world beat back the virus.

"Ontario has lost control of COVID. I say that because we're no longer able to do contact tracing. We're no longer able to do testing in a reasonable period of time," Colin Furness, an infection control epidemiologist at the University of Toronto, said Sunday on CTV News Channel.

Oughton said he would not be surprised if other jurisdictions followed Toronto's lead in the near future, reducing their contact-tracing efforts because there are too many cases coming in for them to stay on top of each one.

THE VIRUS IS SPREADING INTO NEW AREAS

The northern half of Manitoba is an isolated place.

Many communities are an hour's drive, or more, from their closest neighbours. Most of the rest are even less accessible than that, because they don't have all-season roads. Anyone wanting to enter or leave the community has limited options: an ice road if the water has frozen over, a boat or canoe if it hasn't, or shelling out for airfare.

In other words, northern Manitoba is a very difficult place for a virus to thrive.

There were three cases of COVID-19 detected in Manitoba's northern health region in a nine-day span early in the pandemic. Then, for more than four months, there was nothing. Not a single case. The province even put a travel ban in place, restricting non-essential travel from Winnipeg and other southern communities because of fears visitors could reintroduce the virus.

All was going well. Then came the past week.

There have been 13 cases of COVID-19 in northern Manitoba since Sept. 27. Seven of them have been traced to one family in York Factory First Nation. There is an eighth case in York Factory and three other Indigenous communities have also reported active cases.

This is the most extreme example of a new phenomenon: COVID-19 showing up in remote parts of Canada where it had not been a problem before.

Nunavut has been hailed as a success story, making it to this point in the pandemic without recording a single case of COVID-19. But that could be changing. Two presumptive positive cases of the virus were detected two weeks ago at the Hope Bay gold mine, and seven more were reported last week.

Although the initial case is believed to have stemmed from an exposure outside Nunavut, the latest outbreak suggests that the virus has finally made its way to Canada's most isolated territory.

THE GLOBAL PICTURE

Nunavut was able to avoid COVID-19 until recently by almost completely sealing itself off from the rest of the world.

Canada hasn't done that, and that leaves it susceptible to COVID-19 arriving from abroad.

Despite a pervasive belief that the border is closed, there are a wide variety of exemptions that allow essential workers, Canadian citizens and permanent residents and their families, international students and others into the country.

More than 49,000 travellers entered Canada by air during the week of Sept. 21 to 27, according to the Canada Border Service Agency, including more than 16,000 passengers who are not Canadian citizens or permanent residents. Another 187,500 entries were recorded at the U.S. land border.

Everyone who enters the country for non-essential purposes must quarantine for 14 days. Not all travellers are following this rule, however, as news of various Quarantine Act violations makes clear.

This is particularly concerning because Canada is not the only country grappling with renewed COVID-19 activity – and some nations are reporting numbers that dwarf what's happening here. France and Poland both reported record high daily case counts on Saturday, while Italy and Germany hit their highest marks since April.

To this point, arrivals from abroad have not been a major driver of COVID-19 spread in Canada. Public Safety Minister Bill Blair said Friday that between two and three per cent of cases have been tied to international travel.

WINTER IS COMING

Evidence is mounting that it is easier for COVID-19 to spread indoors – especially in places where people are eating or loudly talking without wearing masks and without distancing properly.

That could be a problem as fall-like weather sets in across Canada, with colder temperatures making the idea of spending substantial time outside less appealing.

Warnings of a "long winter" have led to a surge in demand for patio heaters and other outdoor equipment, but many Canadians may find it difficult to brave the elements more than they normally would.

Pair that with indications that "pandemic fatigue" is setting in, and some experts are concerned that some Canadians may adopt risky behaviours this winter – potentially easing the path of COVID-19.

"I am concerned that there's going to be more mingling than there should be," Furness said. He would like to see hard-hit regions shut all bars, restaurants and gyms until the virus is better brought under control.

Dr. Brian Conway, president and medical director of the Vancouver Infectious Diseases Centre, said Saturday on CTV News Channel, that Canadians need to brace themselves for extended isolation, even if a full lockdown never happens.

"Many people are not accepting that the old normal is gone for a long time, that we have to embrace a new normal," he said.

"We need to get messaging out there so that people feel good about making the right decision, and the numbers go down."