麻豆社国产

Should you get a COVID vaccine if you’re pregnant? Does your second dose have to be the same one as the first dose? Can fully vaccinated people get together without masks?

Those were just a few of the questions posed by members of the public recently as Dr. Mark Lysyshyn, deputy chief medical health officer for Vancouver Coastal Health, answered during a Q&A session on the topic of COVID-19 vaccines over Facebook Live.

Here is an edited version of some of those questions and answers.

Q: Should I be concerned about having a bad reaction to the COVID-19 vaccine? If I’ve had a reaction to a vaccine before is it safe to get the COVID vaccine?

A: Most reactions are extremely mild. In a very small proportion of people, there can be allergic type reactions like hives or more severe allergic reactions like anaphylaxis.

The COVID vaccines that we're using are actually quite different than other vaccines that we used before. So, just because you've had an allergic reaction to one vaccine, doesn't mean you'd have an allergic reaction to this vaccine. There's one particular compound in those vaccines called PEG - polyethylene glycol - that people can have allergic reactions to. It's a very specific allergy, but if people have that, then they might not want to get either the Moderna vaccine or the Pfizer vaccine. Although they could get the newer vaccines that have been approved in Canada like the AstraZeneca vaccine or the Janssen vaccine because they don't have that compound.

Q: Should you take vitamin C or other vitamins before getting immunized?

A: There’s no need to take any specific vitamins in advance of immunization. Taking those vitamins has no impact on the immune response.

Q: Should you get the COVID vaccine if you are pregnant? Or if you are planning to become pregnant?

A: In the studies that looked at the vaccine, they didn't intentionally include pregnant people, so we haven't studied that very well. But from what we know of other vaccines and what we know about the risk of COVID in pregnant people and young babies, we recommend that (pregnant women) do get the COVID vaccine, because they're at higher risk of bad outcomes from the COVID virus than we believe they would be from the COVID vaccine.

Q: Can people going through chemotherapy get the vaccine?

A: Yes, they will be offered the vaccine.

Q: What will life look like after the vaccine?

A: When people get the vaccine we know it doesn't work immediately. It takes about two weeks before the immune system starts really being able to protect the person against COVID. At the moment, we don't recommend that people change any of the public health measures that they're used to - things like physical distancing, hand washing, mask wearing, limiting gatherings.

The vaccine prevents severe disease and it also probably does reduce transmission, but we don't have all of the evidence on that yet.

It may be that we can start changing our behavior in the future as we get more and more of the general population immunized.

Q: If I get the vaccine before my mother, could I still be at risk of transmitting the virus to her?

A: Yes there is some risk of that, although we do believe it is reduced.

Q: After the first vaccine can you hug and stop restrictions with your senior parents?

A: That's something that people will have to decide on their own. At the moment it’s not recommended that you change anything after the vaccine because we still think that there is some risk. But over time we're going to learn more about that and hopefully we'll get to a place where we can hug our elderly parents after we've had the vaccine and after they've had the vaccine as well.

Q: Should you get the same type of vaccine for the second dose that you had for the first dose?

A: It's ideal for people to receive a second dose of the same vaccine. Currently we recommend that you go back to wherever you got your first vaccine to get the second one. But we also know that it's likely because of our experience with other vaccines that it would also be OK to get a second dose of a different vaccine.

The National Committee on Immunization has recommended that if you don't know what vaccine you got or you can't get the same vaccine as you got, and you should go and just get another vaccine for your second dose. Currently, though, we're not giving second doses in B.C.

Q: How effective is the first dose of the vaccine?

A: We mostly have experience in B.C. with the Moderna and the Pfizer vaccine, and we've seen that the effectiveness is very similar from a single dose to what was seen in (clinical) trials. It's about 90 per cent effective at preventing symptomatic COVID infections. I know there is some concern about the AstraZeneca vaccine and the Janssen vaccine that their effectiveness might be lower, because the studies show about 65 per cent effectiveness. But what's important to remember is that none of these vaccines have been compared head-to-head in a trial. Conditions in one research study can be quite different than the conditions in another research study. We know they're all effective vaccines.

We’re going to be using the AstraZeneca vaccine a bit differently than the Moderna and Pfizer vaccines because this vaccine is not recommended for people 65 years and older. And so we're going to be using it predominantly for people who need to be in workplaces where they have to be there in person.

Q: Is the COVID vaccine different from the seasonal flu shot?

A: It is different. For the seasonal flu shots, we have two different types of vaccines. For the flu shot, we're using versions that have either been inactivated or they're still alive but they're attenuated, to develop immunity. But for these COVID vaccines we're not using versions of the virus, we're using different mechanisms of getting our own cells to develop this spike protein that will be recognized. So these are actually different types of vaccines than we use for the flu vaccine. The other thing that's different about the flu vaccine is that we change it every year based on the circulating strains, and we have to see whether something like that would be needed for COVID-19. We just don't know that at this time.

Q: Why have other countries like the U.S. vaccinated more people than in Canada?

A: That mostly has to do with is the supply of vaccine that has been available, and where the vaccine producers are. The United States has a number of domestic vaccine producers and so the vaccine is produced in that country and they were able to make contracts with them and get large amounts of doses for their population. In Canada we actually have no domestic producers and so we've been reliant on vaccine coming from other countries. We do have good contracts with multiple vaccine producers so should catch up pretty soon.

Q: Have you seen COVID spread or positive tests from people who have been vaccinated?

A: We have seen cases in people who have been vaccinated with one dose and even with two doses. And there's a few different ways that that can happen. The first thing is that it takes up to 14 days for people develop COVID after their exposure, so people could be exposed to COVID before, or even a few days after they get their vaccine, and the vaccine would not be effective in preventing those infections. The vaccine really doesn't start to work until about two weeks after you are immunized. So, if you get exposed around the time when you’re immunized, you may still get COVID. The other thing is that the vaccine is not 100% effective. So it doesn't eliminate the risk of COVID, it just reduces the risk. We do know from the studies that when people get COVID after they've been immunized it's much less likely to be severe and much less likely to result in death.

Q: For those of us who have been vaccinated, can we travel yet internationally and domestically?

A: It's not recommended that people travel for non-essential reasons but people are allowed to travel domestically. There are certain ways that people can travel internationally as well, but they still need to comply with all of the quarantine requirements, testing, the mandatory stay in a hotel and then the isolation. So, the vaccine doesn't change any of that right now. And we don't know to what degree it will change that in the future.

Q: When do you think everybody in the Vancouver Coastal Health region will be able to get their vaccine?

A: I think we've been announcing that basically by the end of June, we hope to have the entire population of B.C. immunized with one dose.

Q: When can groups of fully vaccinated people get together without masks?

A: The U.S. CDC has just announced new guidelines for people once they've been immunized, saying that they are able to gather with other people in small numbers who have been immunized without masks. We haven't made that recommendation yet in Canada. We're also not nearly as far along the immunization campaign as the U.S.

Q: Is there a plan to track those who've been immunized with one dose to see how effective it is?

A: Yes, we've got very good vaccine surveillance here. This is what has allowed us to extend the interval between the doses, because we have been able to study the effectiveness of the first dose in B.C. It's being looked at on an ongoing basis. We want to do what's safe and so obviously if we start seeing the protection from that first dose waning, we would obviously want to introduce the second dose, but so far we're only seeing the benefits of extending that interval.

Q: How are people who are homebound going to get their shot?

A: Already people in that category are starting to get their shots. So are people who are recipients of homecare and home support on a long-term basis. And as the immunization program rolls out, if there are additional people who can't get to clinics, then outreach strategies will be used.

Q: Are current vaccines effective against the variants?

A: It does look like the vaccines that we're currently using are effective. (The variants) were first identified in the UK and the UK has been using the same vaccines that we are using and they seem to be effective against these variants. But it may be the vaccines are not effective against all of these variants. So it may be the next dose that people receive of the COVID vaccine may be slightly different than the first dose that they got to address these issues. It may be that we require annual immunizations against COVID that take into account these variants. It may just mean that we need a higher level of herd immunity to control the virus, but we'll have to see.

Q: Is there any idea if and when children may be vaccinated?

A: None of the research studies have looked at the vaccine effectiveness or safety in children and so that's why the vaccines are not being offered for children. Initially children will probably be protected simply through adults around them. We believe that the school system for instance would be much safer once all the adults in the school system are immunized because the most likely type of transmission we see in the school system is the adult-to-adult or adult-to-child. The least common transmission is child-to-child. We obviously want to get a vaccine that's safe and effective for children as well and so those studies are underway now. And so hopefully by the summer or maybe the fall we will know that some of these vaccines that we're using now are safe and effective for kids.

Q: We’ve heard about cases amongst people who have been vaccinated, such as in long term care sites. How is that possible?

A: Recently there has been an outbreak in a long-term care facility that's been in the news, but actually most of the cases in that outbreak are people who are not immunized. There are a few cases in people who had been immunized because again the vaccine doesn't work perfectly.

Q: Why aren’t we using drive-thru vaccine clinics?

A: We are creating more and bigger immunization clinics called mass immunization clinics. We're not doing drive thru immunization clinics. The reason for that is that people need to be monitored after a vaccine because there is a small risk of anaphylaxis. And so we don't want people getting in their cars if they have anaphylaxis.

Q: Are there other vaccines that may be developed and brought to Canada this year?

A: Yes. Health Canada has just also approved the Janssen vaccine or the Johnson and Johnson vaccine made by Janssen. This is an interesting vaccine because it only requires one dose. And so that makes it a little bit easier to administer, and it also is very fridge stable. I believe we have contracts with three additional vaccine manufacturers so we may have up to seven vaccines available at some point during the response.