Toronto reported 191 new infections on Thursday, bringing the city's total COVID-19 cases over 18,000.

Of those cases, 41 are currently hospitalized, 1,178 have died, and 15,624 have recovered.

While the second wave has already started, Dr. Eileen de Villa, the city's medical officer of health, urged residents to continue following all public health measures to curb the virus's spread.

"I think the most important part here is that the future actually is in our hands," de Villa said.

"We know how this disease is transmitted from one person to the next, and we know what we can do to mitigate the risk."

De Villa joined CP24 on Thursday afternoon to answer questions about COVID-19 testing and other coronavirus-related queries.

CP24: Who can get tested for COVID-19?

De Villa: We heard from our provincial partners that we needed to take a more strategic approach to testing, and I think this is a good thing. As your situation changes, you need to change your response. And I think that's a very responsible thing to do. What has been announced by the province is that the testing resources through the assessment centers are really meant for those circumstances where we know those tests are likely to provide the most value -- people who have symptoms consistent with a COVID-19 infection, or those who are at high risk, given the nature of their exposure to somebody with the virus. For other people who have some concerns but aren't actually symptomatic, the province has made available another route for testing through certain participating pharmacies.

CP24: Why is the city's waterfront remain one of the COVID-19 hotspots?

De Villa: What we've done on our maps is tried to show people in Toronto, where people who have COVID-19 infections are actually located. What's interesting is that what we have is their home address. That doesn't necessarily tell you where they acquire the infection. For some people, that will be the case. If you live with somebody who has COVID-19, you're at a higher risk of acquiring that infection. But that first infection may not have been acquired in your local neighbourhood. What we know about COVID-19 is that it's transmitted from person to person. And it doesn't just happen at long distances. You actually have to be close enough to somebody to get exposed to the respiratory droplets that come out of their mouths and nose when they speak or sing or shout or frankly, even when they breathe. It's close contact with somebody who has a COVID-19 infection, and its behaviour that actually creates the circumstances that give rise to the virus. That's why we keep talking about watching your distance, wearing your mask and washing your hands, because that's the best way to reduce that transmission.

CP24: Prime Minister Justin Trudeau talked about the second wave already underway in some parts of Canada. What about a third wave? Is there a plan for it?

De Villa: There are a number of different scenarios in which COVID-19 can play out in the future until such time as we get more effective treatments and a vaccine. And certainly, people have talked about a second wave, which gives rise to what about a third or a fourth wave. That's why I prefer not to use the term second wave. I talk about it as increased activity or resurgence of COVID-19 activity, because we don't know whether it's going to come as a single sort of large waveform, and what subsequent waves might look like.

But I think the most important part here is that the future actually is in our hands. We know how this disease is transmitted from one person to the next. And we know what we can do to mitigate the risk. Some people are not going to be able to mitigate the risk. If you work in a healthcare setting, and you're actually taking care of COVID-19 patients, yes, there are good protection measures you can use for yourself, but it might even be difficult. Others work in essential services. And again, it is more difficult to protect yourself in certain circumstances. But for those of us who can choose to avoid activities where you might get into close contact with other people, where you don't really need to be there, this is the best thing that we can do to prevent a huge second, third or fourth waves, whatever the case may be of COVID-19 in the future. I think that's on all of us to actually participate in.

CP24: British Columbia has taken runny nose off their testing criteria. However, in Ontario, some students who have runny nose are not allowed to go back to school until a COVID-19 test has been done. Do you think it will fragment the system and keep parents and other people who experience the same symptom away from work?

De Villa: There is a lot of conversation around this. And we are evolving our processes and you know, as our understanding of COVID-19 and how we can best get schools functional. As you just said, BC has changed its practice. I understand that there are lots of conversations happening, particularly with the Ministry of Education and the Ministry of Health, around how best to manage COVID-19 control measures in the context of schools and school reopening. So, stay tuned on that one. Please know that it is actively being discussed, as I understand it by the relevant parties.

CP24: There are concerns that people will not get tested and lie on their forms to get back to work or school due to long lineups at testing centres. How worried are you that if things don't change when it comes to testing that we could see even more severe cases?

De Villa: I think an increase in cases and the potential for an increase in cases are always of concern to all of us. That's why I think this is a combination as much as possible between what we can do as individuals and what government can do to support individuals in taking on appropriate self-protection measures. We need at an individual level for people as much as possible to limit their contacts to their households or the essential support. The more distance you have with people who might be infectious, the more you reduce your chance of acquiring COVID-19 and then creating a further spread. It's all about watching your distance, wearing your mask and washing your hands at an individual level and staying home when you're sick. From a government perspective, the idea is to provide appropriate policies that allow people to facilitate people's ability to engage in those self-protection measures. There has been a lot of advocacy around how best we can ensure that people have the necessary ability to take time off to follow these self-protection measures to get tested when they should to protect our whole community.

CP24: With these new testing guidelines announced today, who are deemed at higher risk to receive the tests when asymptomatic? And what about families with children in school, families who live and care for with care for elderly parents? Why would pharmacies not be used for reassurance testing?

De Villa: As I understand it from the province's new announcement, what we're looking at here is trying to make sure that we have the assessment centres and the testing provided through those assessment centers to be available to those who most benefit from that test so that as a community, we can all benefit as much as possible from those particular tests. When we're looking at those who are high risk, particularly what's top of mind will be those who significant exposures to those with COVID-19 infections. That would be the top of the list there. The second part of the question had to do with reassurance testing. That sounds to me if I've interpreted it correctly, the kind of testing that someone might do that they don't really have a significant risk of exposure for COVID-19, but they're concerned for whatever reason, about their COVID-19 status or whether or not they might be infected.

As for those visiting loved ones at long-term care homes, according to the provincial standards, as I understand it, that's one of the populations for whom testing is deemed to be important to happen at an assessment center. That's what I think they call a targeted population or a designated population for testing. They would be seen within the context of an assessment center, even if they are asymptomatic. Also, if you have symptoms that might be consistent with a COVID-19 infection, that's a situation in which you would want to go to an assessment center. And that becomes even more heightened if you have symptoms in the face of known exposure to somebody who has a COVID-19 infection.

CP24: There have been more than a few staff members in Ontario schools testing positive. Why are teachers not being tested before entering a classroom full of kids? Shouldn't it be mandatory?

De Villa: I can appreciate the sentiment behind that. Obviously, we're all very concerned about the health and safety of those in our school communities, whether we're talking about teachers or talking about the children in their classrooms. I think that when we look at the results of what has happened thus far, throughout the world in this COVID pandemic, and we see what benefits do you derive from different kinds of testing, the new strategy proposed by the provincial government actually provides for the best use of the resources right now. And things, of course, change over time. Different circumstances warrant different approaches. But at this point in time, I think that the notion of testing people out of concern, without a good solid rationale for testing, as well-intentioned as it might be, isn't necessarily the best use of resources.

And fundamentally, what it comes down to at the end of the day is what we can do to prevent infection from happening in the first place. And I know you've heard it heard me say it before, and you're going to continue to hear me say this, watching your distance is number one. Avoiding that close contact wherever possible. Where close contact cannot be avoided, wearing a mask is a reasonable thing to do to protect yourself and protect others. Recognizing that the shorter the time of exposure, the better off you are, and washing your hands is that third W. I just can't emphasize these three W's enough. They are so very important in preventing infection.

CP24: Why isn't there an instant saliva test yet?

De Villa: I think there are a number of different testing methods that are hopefully coming down the pipe and will be with us soon. That's my understanding, again, from our provincial counterparts. And these are, I think, we have to remember that these are medical tests that help diagnose or understand whether there might be the presence of an infection. And I think we can all understand that you would want that to be a very high-quality test and a well-studied and understood test before releasing it for mass use in a population. I do think that it's important that we expedite these tests as much as possible in order to address the situation, but as with everything, there's a bit of a balance around making sure that you've got a reliable test and wanting to get that test out and in use as quickly as possible.

At the end of the day, prevention is still the best strategy. We know how the disease spreads. It spreads from person to person, when you're in close enough contact, that the respiratory droplets that come out of an infected person's nose or mouth are close enough that they get into your nose and mouth or your eyes. Watching the distance, wearing the mask, washing your hands. I know we're tired of hearing that. But these are really solid strategies to prevent the spread and prevent the unnecessary use of testing resources in circumstances where we simply could have avoided the contact or the potential for risk in the first place.

CP24: When is the right time to get a flu shot? And how long do they last?

De Villa: A flu shot is important to get, especially this year with COVID-19 around. Flu shots should be available starting next month. When you can get it is a good time to get it. Yes, there is a little bit of a period of time before you get to maximal effectiveness. But when you can get a flu shot as soon as it becomes available is the best time to get it. If you're febrile or really sick at that moment, that's not a good time to get a flu shot. I would get assessed, but by all means, when you can get a flu shot once it becomes available, please go out and get it, especially this year.

This interview has been edited.