Dr. Peter Salk, a physician and professor of infectious diseases and microbiology at the University of Pittsburgh, whose father, Dr. Jonas Salk, developed the first polio vaccine, told Democracy Now how the COVID-19 vaccine works and how it is different from traditional vaccines:
[T]his is really so extraordinary, because back in those days there were only fundamentally two approaches to making vaccines against viral illnesses: the killed virus, whole virus, inactivated so that it can’t do harm, but it has all of the materials of the virus that will stimulate the immune system to produce antibodies and so on; the other approach was a live virus, living, that had been weakened in the laboratory or in passage through animals, so that it would cause an infection but not produce deleterious effects. So, that’s all that was available back then. Now, since then, there’s been so much that has been learned about how viruses work, their makeup, their genetics, how they infect people, and so on. And what we have today is just an explosion of new techniques to make vaccines very quickly.
So, these two mRNA vaccines that have come out are making use of one of those techniques, which is to take the genetic material of the coronavirus and focus on just that part of the genome that codes for the so-called spike protein, that many people have heard about, that’s on the surface of the virus, and that’s the protein that the virus uses to get inside of cells. So, it’s been constructed in just the right way. And what’s been done with those two vaccines is just to take that pure DNA, encapsulate it, inject it into the muscle; it gets into the cells, and that RNA instructs the cells that that RNA gets into to manufacture the spike protein. Doesn’t manufacture anything else about the virus. There’s no coronavirus that’s produced. It’s just this pure protein, that then the immune system sees and recognizes, “Hey, that’s something new. I don’t like it,” and the body makes antibodies against it. And it’s those antibodies then that end up being protective against developing severe coronavirus. Vaccine, because when the virus comes into the body — the real, actual virus — those antibodies are all tooled up to fight against it. So, that’s one approach.
Another kind of approach that’s available now to make a vaccine very quickly is taking the genetic instructions and putting them into a different kind of virus that’s harmless, like a common cold virus, the so-called adenovirus. And that virus then can get into the body, transmit the genetic instructions, and then the same thing happens: The body makes the right kind of antibodies. You can put that even into a measles vaccine virus that’s harmless. That’s another kind of approach.
(Source: Democracy Now)