Time & Date
Tuesday, February 16, 2021, 6:00 pm
WBUR CitySpace Virtual EventOpen in Google Maps
The arrival of the COVID-19 vaccine marks a new era in medicine for many reasons, bringing both praise and speculation. The technology involved in its creation, the unprecedented speed of its production and the urgency of its rollout have instigated many questions about its safety and efficacy.
In the first of a four-part virtual event series on the COVID-19 vaccine, CommonHealth reporter, Angus Chen, sat down with Galit Alter, professor of medicine at Harvard Medical School, and group leader at the Ragon Institute of MGH, MIT, and Harvard to answer some of these questions. The event began with a crash course on the history of vaccines from Endless Thread podcast hosts, Ben Brock Johnson and Amory Sivertson. You can hear more of investigations into vaccines by listening to their series, "Infectious: The Strange Past and Surprising Present of Vaccines — and Anti-Vaxxers."
On the scientific process of creating progressively safer vaccines
Galit Alter: The technologies just got better and better. We got more cost effective. We got faster. And more importantly, we also learned exactly the flavors of vaccines that the immune system seemed to respond to most effectively. And so what I mean by flavors is instead of using, you know, a protein, which we often think of is like, you know, a chunk of steak or a chicken, they're made from these molecules, right, that are really important. That is protein. Well, proteins, these molecules that are coming from the virus, are also made from these same strings of molecules that we can actually synthesize through chemical processes.
So we were able to make this with our technologies getting better and better, making them at higher quality. But then what we realized is that those technologies to make proteins sometimes still take an awful long time and the amount of quality control required to make sure that every single protein is folded absolutely perfectly just took too long. It would take us a year just to make sure that those particular vaccines looked perfect and induce the perfect immune responses. And that's when we began to think, about 20 or 30 years ago, about the possibility of instead of trying to make these particular portions of our pathogens in a dish, "What if he could tell the immune system itself to make those particular parts of the virus?"
So now what we have are these enormously fantastic technologies like the mRNA vaccines and the viral vectors that form the basis of the J&J vaccine that essentially just provide the software to the immune system. It just provides the code to make these particular portions of our pathogens, only make that one tiny little part of the pathogen without taking the risk of exposing the immune system to the whole virus itself. But now the immune system makes that protein in our bodies and trains us in real time to respond to it. That discovery has blown apart the vaccine field, essentially because now we can make these faster, we can make them stably, we can make them with incredible high quality. And we let the immune system make these components of the virus naturally and expose us only at minimal risk to the component of the virus that we want to attack.
On how COVID-19 immunity is shared during pregnancy
Angus Chen: I wanted to quickly ask about something you briefly mentioned just now: that pregnant women might give antibodies to their infants if they got the vaccine. Does that mean you could pass on immunity to COVID-19 if you got the vaccine and you were pregnant?
Alter: Well, that's the whole point of the placenta. So that's my favorite organ in the body. It's a funny thing to talk about on a radio show, but it's a really fascinating organ. We're connected to our babies by an umbilical cord that goes through an organ called the placenta, and the placenta shoots over oxygen, changes blood, essentially transfuses the baby all the time, gives it nutrients. But what it also does, super importantly, is it delivers antibodies and immunity to our infants. And so one of the reasons we're so excited about vaccinating pregnant women is not only will we be able to protect them from getting COVID-19, but they will then also transfer antibodies to their babies. And that means that babies are born on the first day of life, full of antibodies that can fight SARS-CoV-2.
But the reason this is so interesting is that in the history of vaccine development, we have never been able to study the immunology of vaccination in pregnancy because people are always terrified about vaccinating pregnant women, because we're afraid that maybe they'll miscarry or they'll have some other complication. And so we always treat it, you know, like sacrilegious, you know, because we want to protect our pregnant women as much as possible because they're carrying the future of our society.
But now, because we want to protect them and we have these very safe vaccines, we can begin to study the immunology of vaccination, which means that for future pandemics that might be, you know, really lethal to babies or to pregnancies, we can now make informed decisions about when it's the right time to vaccinate, which platforms work the best, and how can we get the best antibodies possible in our babies so they can be completely resistant to pathogens when they come out of their moms.
On why we need vaccines to achieve herd immunity
Alter: So the idea of herd immunity really is essentially that we can protect our entire herd, right? That essentially everyone will have immunity or will have enough immunity in our community; enough people will have robust immune responses that will essentially keep the virus out. Right? We can essentially completely block it from entering that population. So even if a couple of people in that population may not have complete immunity or not be vaccinated, as a community, we're keeping the virus out because we're limiting the possibility of transmitting within that population. And that is the concept of herd immunity.
Now, you could theoretically wait until the virus passed through enough individuals and you would have to wait until enough people built natural immune responses that could eventually give us enough of that immunity that stands that wall up to prevent the virus from getting in right into that population.
But we don't know how long it takes to get to that very high number of individuals that need to have immunity if we wait for natural infection to occur. It could be a month. It could be a year. What we learned from New York, when the virus is going crazy back in March, is they only reached 20 percent herd immunity when they let the virus go crazy. And even Sweden, that never shut down and barely wore masks in the summer, only had twenty five percent antibody positivity in their population. So they were nowhere near the 70 to 75 percent levels of immunity we need in our population in order to truly create that herd immune response that will keep the virus out.
What vaccines do is they accelerate the time in which we can stand up antibodies in our population. We can essentially immunize vast numbers of individuals and essentially get those antibodies to sufficient levels where they can completely keep the virus out. So the reason we need a vaccine is to essentially get ourselves out of this pandemic as soon as possible. And that is the reason why we're really trying to think about ways that we can stand up immunity in a strategic way initially and those that are most vulnerable and then start to work our way through the population and give it to as many people as possible so we can eventually have that level of an immune response that will just keep the virus out.
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