Science friday. I'm ira plato. Later in the hour a look at how global change is upsetting vital ocean currents in the atlantic and trip to the bakery for some sour dough. Bread kikori but i if you've been online at all in the past few weeks you've probably seen discussions about the drug ivermectin. It was originally developed as an anti parasitic treatment for livestock and in two thousand fifteen. The nobel prize went to scientists. Who found that. It helped control parasitic diseases in humans as well but now some groups have been promoting the drug as a treatment for cova nineteen even though the corona virus is a virus not a parasite joining me now to help unpack that and other news from your covy. Newsfeed is dr angela. Rasmussen research scientists at veto inter vac. The university of saskatchewan's vaccine research institute in saskatoon saskatchewan up there in our friends in the north in canada. Welcome back angela. Thanks for having me back ira okay. So what's the deal with this horse. Medication story ivermectin. In some ways is really the new hydroxy chloroquine. I'm not entirely sure how ivermectin came on the scene as possible treatment for covert nineteen but multiple clinical trials have been conducted to look at ivermectin for treating cova nineteen preventing covert nineteen and it. It doesn't appear to do either one of those things the fda as well as the one of the manufactures of ivermectin merck Have both released statement saying that. That ivermectin cannot be used for for treating cove nineteen and that people should not use it especially as a substitute for vaccination and you know for me like months ago when merck said. Don't take ivermectin for cove. Ed i mean that's not usually the kind of thing that a pharmaceutical company says about a product that they make. Please don't take our product you know. All of that along with the data is really strong. Indication that ivermectin doesn't do much In the way of treating cove nineteen in it certainly doesn't prevent it and it certainly is not a good alternative vaccination as some people who are promoting ivermectin for this purpose have said while ivermectin is on the. who's list of essential medicines. It's a crucial medicine in. You mentioned that. The discovers of ivermectin won the nobel prize because it is used for treating some some really horrific parasitic diseases. One of those African riverblindness is a disease caused by worms that can ultimately results as the name implies in loss vision most of the listeners. Probably our most familiar with ivermectin as an ingredient in heart guard or any of the other types of de worming medications that they give pets. It's very effective for treating parasitic worm. Infections it is not effective however for treating cove nineteen. And this is what really concerns me are people who are promoting ivermectin as a valid alternative vaccination for preventing cova nineteen and. This is just simply not the case if you're taking ivermectin every day not only If you are taking off label can use suffer the consequences of taking too much ivermectin. Because if you're buying ivermectin in a dose that's meant for horses or cows or large animals that have considerably more body mass than we do You could overdose on it but also you are going to continue to be vulnerable to kogo nineteen and if you think that that ivermectin is providing the same protection that a vaccine would You're you're going to potentially put yourself at a greater risk. Let's move on to something. That has a bit more evidence behind it and that is boosters. There's been a lot of talk about boosters. What israel is doing what other countries are doing. Will there be a third shot. Who will get it and win. Yeah this is really kind of one of the hot topics of the hour and really a lot of this is based on evidence that i was pretty skeptical of it. I but i'm i'm starting to be more and more persuaded. We're starting to see more evidence at really the population level that over time the marin vaccines particularly the pfizer vaccine appears to be decreasing ineffectiveness preventing symptomatic covert nineteen. Now this. this has been a really confusing topic. I think because we are also hearing all the time about breakthrough infections and how they're more common with the delta variant and that's not necessarily due to this decrease in effectiveness And that's not always talking about cases as cases of symptomatic cova nineteen sometimes it conflates Symptomatic disease with pcr positively but overall. This is really important. A decreasing effectiveness is something to be on the lookout. For because in the clinical trials to evaluate these vaccines they were expedited because this was an emergency situation So we weren't able to look at durability we don't know how long these vaccines are going to have a long-term protective effect and it is entirely possible that third dose would always be needed because oftentimes one of the reasons. Why vaccine clinical trials. Take such a long time as they try multiple configurations of the dosing regimen to determine the optimal one for establishing durability we have many vaccines that are three dose regimens usually with the third dose being given after a longer time interval from the second dose which is really what's being discussed now. The reason why this is important is not just to prevent a symptomatic breakthrough cases. And i think this is one of the things that has really confused people because there has been some talk of while. You're moving the goalposts. I it was just to to prevent cova and now it's to prevent all these infections. And why do i care if i get infected. If i'm just positive on a test in. I don't have symptomatic cova but for people who are already high risk of developing severe cove in nineteen an increase in the number of symptomatic cove nineteen cases in healthy low risk vaccinated. People probably means that there could be an increase in the number of severe cova nineteen cases in high risk people who are more likely to end up in the hospital. More likely to die from having cove ed so it does make sense to to say well. We do have a surplus in many parts of the country. Vaccines right now. We do have increasing evidence that a third vaccine or even a mix and match vaccine regimen with the third dose is safe if you can increase vaccine effectiveness to take it from fifty to seventy percent. Backup to ninety percent in terms of preventing. That's something that we would want to have and then finally As i mentioned before many vaccine regimens are three dose regimens and the reason for that third dose in the data to support this to the kovic. Vaccines is that if you haven't increased interval between your second and third doses your immune system basically says you know what this is something that i might continue to see this pathogen. So i'm really going to exert of the resources needed to to really make that long term memory protective immune responses and. I hope that that's what we will get from the third vaccine now. Of course we don't know for these vaccines because we weren't able to look durability but knowing what we know from other vaccines and other types of vaccines This usually applies that that sometimes booster doses are needed but they're not needed at frequent intervals. And they do results in immunity that lasts for years in most cases. Can we learn anything from the israeli experience on this. they've already been using third doses will absolutely and unfortunately what we can only learn is about the pfizer vaccine in israel on because that's predominantly the one that they're using but israel has really been a wealth of information because they have had such a successful vaccine campaign and they've been collecting so much data on it. So i think that probably we will be able to learn a lot more at least about what the benefit is to a third dose from the for the pfizer vaccine at the population level. I hear you saying or implying that the modern dern vaccine may be longer lasting than the pfizer vaccine well. A study came out this week in the journal of the american medical association. That suggested just that now. There aren't very many studies that are directly comparing these two vaccines. And i think people have assumed that they're basically the same vaccine as far as what the marin a is in codeine But there are a couple of differences. The pfizer vaccine is given in a lower dose thirty micrograms compared to the hundred microgram dose of moderna And they have a different interval Three weeks for five or four weeks for moderna and they also use a different lipid nanoparticle to deliver the vaccine That ends up going into your cells where the spike protein gets made. All three of those things could make a difference potentially Study in jama showed It showed that that the pfizer vaccine was reduced in terms of its effectiveness in people who received that compared to moderna and also that they had lower levels of neutralizing antibodies..