In her weekly segment with CP24, Dr. Eileen de Villa, Toronto's medical officer of health, answers viewer questions about COVID-19, including vaccines, variants and the latest public health measures.

CP24: We've been reporting the clashes at Lamport Stadium as crews clear the encampment there. Those who live in encampments have said they don't feel safe at city shelters, hotels and other accommodations because of COVID-19. Can you tell us what the situation is in those settings? Are they overrun with cases?

De Villa: I'm pleased to say that at this point in time, there are no active COVID-19 outbreaks going on in any of the shelters in the city. And this is good news. It reflects the fact that COVID-19 activity here in the city writ large is actually quite low right now. This is a good thing. In fact, there hasn't been an outbreak in the shelter system since June 8 at last count. And again, this is all good news. I think partially a reflection of low activity in terms of COVID-19 in the city and partially a reflection of all the work that those who are involved in the shelter system are putting into place in terms of infection prevention and control measures because these are important. And finally, there's vaccination as well, which we know has been a significant undertaking throughout the entire city. There are special efforts being done to ensure that vaccinations are offered to those who are using the shelter system and those who work in this system.

READ MORE: 22 people arrested after Toronto crews dismantle encampment at Lamport Stadium

CP24: Has that side of it been difficult, the idea of getting vaccinations to people who are experiencing homelessness?

De Villa: It has its own unique challenges. There are people who are users of the shelter system, and they're not always consistently there. This is a population that does tend to move somewhat. And when you're dealing with a vaccine that actually requires two doses in order to be fully vaccinated, there are clearly some logistics issues. But I continue to be really impressed by the efforts made by those who are going in and providing vaccines. Some of them are associated with us at the city and Toronto Public Health. Others are those who come from other vaccination partners -- hospital partners and other community agencies. We've all been working together with our shelter partners to make sure that those vaccinations are offered both to staff and clients of shelters. We're going to continue doing that for the foreseeable future.

CP24: Dr. Kieran Moore, the province's chief medical officer of health, said Ontario needs to aim for a 90 per cent vaccination rate order to ensure community-level protection against the more infectious Delta variant. Is that attainable?

De Villa: I think that what we've seen thus far in the vaccination campaign, certainly here in Toronto, is that there is a strong interest amongst Torontonians to get vaccinated. And I think as we see more and more people get vaccinated, it makes a greater and greater case for those who might have had some reluctance, to begin with, that actually these vaccines are safe, and they are protective. We're seeing this throughout the city of Toronto, throughout the province and all over the world. So, I think when it comes to vaccination, there's no question that the higher we are able to drive up that vaccination coverage rate, the safer we will all be. This is especially important in light of that delta variant, which we are seeing, both here and in other jurisdictions all over the world, is more transmissible than the previous COVID variants that we've dealt with in the past.

READ MORE: Ontario's top health official suggests new vaccination target to account for risk posed by Delta variant

CP24: I think there's no question that people are still interested in getting a vaccine, whether it's the first dose or second dose and the numbers support that. But the rates have dropped off significantly recently. How realistic is the 90 per cent goal? How do you convince somebody who has been unconvinced up to this point to get a vaccine?

De Villa: I think when you look at other jurisdictions' experiences, they are seeing that as people understand more and more that the vaccines are, in fact, safe. They're seeing this in practice over and above the fact that they're licensed by the regulatory agencies. They're also increasingly seeing that those who are vaccinated are those who are most protected from COVID-19 and, in particular, the Delta variant. We know that getting fully vaccinated is one of our best defences out there in respect of protecting ourselves and those around us from COVID-19. So, I'm not I'm prepared to say that we're done yet. In fact, as you mentioned, we're still seeing thousands of people coming forward. Not only that, their vaccinations completed, but also getting first doses. So, I remain quite optimistic. And I have a lot of faith in the people of Toronto, which has certainly been well earned over the course of the pandemic.

READ MORE: De Villa says she has faith Toronto can push vax rate higher amid efforts to get even more shots in arms

CP24: A viewer is wondering if a variant can emerge in the fall with the capability of shutting the province again.

De Villa: I would say that look, as far as I'm concerned and based on the science as we understand it, this is actually up to us. The more we can contain the spread of covid 19, the more we're able to reduce the transmission of COVID-19, the less opportunity there is for the virus itself to mutate and to create new variants that are more transmissible and potentially more trouble-causing. I think that's why you're continuing to hear those of us in the public health sector ask for people to get vaccinated -- to get that first dose, and then at the appropriate time to get that second dose to be fully vaccinated. Because this is one of the best weapons we have right now to help protect us and our whole community against COVID-19. That accompanied by practicing just good public health measures, washing your hands, keeping your distance, wearing your mask, and those high-risk situations and, of course, staying home and away from others when you have symptoms that are consistent with a COVID-19 infection. This, in concert with vaccination, is how we reduce transmission in our city, and how we prevent the ongoing spread, and then the development of variants of COVID-19, which may cause more trouble for the future. That's our best approach.

CP24: A viewer asks, when is Health Canada finally going to approve the maternal vaccine for 12- to 17-year-olds, especially when all doctors are saying that Pfizer and Moderna are interchangeable and the same for all intents and purposes? It's been a long time since Moderna has asked for approval.

De Villa: I'm sure that Health Canada is going to look at the materials that they have received from Moderna and will make their decision in due time. I know that they have a very rigorous process that they follow, and I support that rigorous process. We want to make sure that as products are licensed for use in Canada, especially for young people, that you want to make sure that all the safeties are in place and that appropriate measures and assessments have been taken. I did receive first a Pfizer dose and a second Modena dose. So, I can, you know, not only vouch for it verbally but can say that I have actually taken that advice to heart and, in fact, implemented it in my own life. It's something I've actually taken personally. So, I feel quite confident in the advice that's been provided by the National Advisory Committee on Immunization and their advice on the interchangeability of the mRNA vaccines.

CP24: Another viewer wants to know if he can travel to New York for a birthday celebration?

De Villa: I have not kept a very careful eye (on border news). I know that the Canadian government has made some initial statements around opening the border, but my understanding is that the U.S. is not quite ready to open up the border to non-essential travel.

READ MORE: Despite Canada's easing, U.S. adds 30 days to travel restrictions at shared border

CP24: A viewer says, "With restrictions still in place. How does Toronto Public Health justify the lack of social distancing on the Toronto ferries? We were there this past weekend. I left the island by noon because of the crowds. Toronto ferries were running with more than 200 people per load coming from Toronto to the island. And there was even less distancing at Centerville as they didn't care to enforce anything."

De Villa: I'm sorry to hear that there was that crowding situation that was noted on the ferry. I would say that there are things that each of us can do that are within our own control. And certainly, one of the things when it comes to the ferries is to the extent that you can be in the outdoor space - the outdoor deck of the ferry. That certainly reduces risk, even if there are many people around. More open spaces or big open-air spaces are generally at lower risk for transmission. I would encourage people to try to keep distance as best as possible. And, of course, the use of a mask certainly helps. And if all passengers are really being very good about their mask use, that goes some of the ways towards reducing transmission risk. But certainly, what I can do is follow up with my colleagues at Parks, Forestry and Recreation, that division at the city and make a few inquiries and see what we can do. But it does rely, I think, on all of us doing the very, very best we can in order for us to reduce transmission in the city. And, of course, I would be remiss if I didn't mention the role of vaccination. I would encourage people to go out and get that vaccine if they haven't already done so.

CP24: A viewer asks when you think mask use will be lifted and not required indoors.

De Villa: This is probably a question that is more directed towards the province. There are a number of regulations in place. But clearly, what we're looking for, I think, is getting more and more of the population vaccinated. And as I mentioned earlier, the higher we can get the vaccine coverage rate, the safer it is for all of us, particularly in light of those highly transmissible variants like Delta. And, of course, we're going to want to see a lack of COVID-19 activity in the community. So, I don't know that we can tie it to a specific date. But I would say that the more we are able together to bring vaccination coverage up and more of us are fully vaccinated and the more we are able to actively participate in those measures that helped to reduce transmission like wearing our masks, for now, washing our hands, keeping our distance and staying home and avoiding other people contact with other people when we're sick, the sooner we will find ourselves in a circumstance where we are able to revert to something a little bit more like life was before COVID-19 and masks not being part of our landscape in indoor spaces.

CP24: A viewer asks, "How safe are health-care workers who got vaccinated back in January, which was almost seven months ago, as we're talking about how there might be a fourth wave due to the Delta variant? Will the health care workers need a booster dose to keep their immunity?"

De Villa: This is a great question from the viewer, and it's actually very much at the top of mind for those who are working in public health and certainly for those who are researchers in COVID-19 vaccines. At this point in time, studies are still ongoing to understand how long the duration of immunity is associated with vaccines. We've seen some studies suggesting that we're not yet in a position that requires widespread use of boosters. We are also seeing some studies that demonstrate that those who perhaps have immune systems that aren't working fully, whether because it's due to a medical condition that they have or treatments that they need to take that there are certain individuals who clearly will be more likely to need boosters as sooner than others. So, I would ask the viewer to stay tuned for now. This is an active area of study, and we'll bring updates as soon as we have information that changes the course of action. But for now, getting fully vaccinated means getting those two doses on board, and I would encourage everybody to take advantage of that if they haven't already done so.

CP24: Since the province is now in step three of reopening. Has there been any thought about reintroducing social circles as part of the reopening plan to allow people to safely expand their close contacts with others while still keeping up with some of the measures necessary for self-protection?

De Villa: I can't really speak for what the province might be looking at in this regard. But that doesn't stop us as individuals around making reasonable choices based on the knowledge that we have accumulated together over the course of the pandemic. And we know that the risk of COVID-19 and its transmission increases the more interaction you have between a larger number of people, and it is especially true if that interaction between a large number of people happens within the context of an indoor environment where there isn't a lot of ventilation or air movement. So, to the extent that you are able to limit your contacts and especially if you limit your contacts to those who are fully vaccinated and you're fully vaccinated yourself, this is, again, the kind of action that we can take or choose for ourselves in order to reduce our risk of exposure to COVID-19 and the risk of exposure to COVID-19 for those in our immediate circles. So, I think lots of knowledge that we've gained over the course of the last several months that we can all put to good use while policy is developed and while actions are developed from a provincial perspective or from a city perspective.

CP24: Final thoughts this week?

De Villa: I think if I had a comment to make at this point, and as we look to the future, I look to our young people. And when I look at the results of vaccination in our youth, our 18- to 24-year-olds are just shy of 93 per cent with at least one vaccine on board. I think we should look to their leadership, and I would encourage people to follow their good example if you haven't already been vaccinated. Go out and do what the youth are doing. Get vaccinated. It's the best thing we can do to protect ourselves and the community around us.