How does the Johnson and Johnson vaccine work?
The Johnson & Johnson vaccine does not use mRNA. Rather, it's what's known as an adenovirus vector vaccine. It uses the more established approach of employing a harmless cold virus to deliver a gene that carries the blueprint for the spiky protein found on the surface of the coronavirus.2 days ago
The virus enters cells, which then follow the genetic instructions to construct a replica of the coronavirus spike. The immune system uses these replicas to recognize — and respond to — the real thing.
The coronavirus vaccine produced by the University of Oxford and AstraZeneca is also based on adenoviruses, as is a Johnson & Johnson-made vaccine for Ebola, which was approved by the European Medicines Agency last year.
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How mRNA and adenovirus vaccines work - Futurity
There are several different ways this can work. We can find (or even make) close cousins of a pathogen. Something that doesn’t make us sick, but still looks enough like the pathogen to give us immunity to both. This is known as an attenuated vaccine. Some of the most successful vaccines are attenuated vaccines. Smallpox, measles, and chickenpox vaccines are all attenuated vaccines.
Another major approach is what’s called an inactivated vaccine; the flu shot is a good example. Here, instead of a close cousin, we use the pathogen itself. But we can’t just inject the pathogen, because that will make everyone sick. So, we boil it or do something that otherwise makes the pathogen harmless.
We then use the inactivated pathogen to show the immune system what the pathogen looks like. The immune system uses that to develop the tools it needs to protect you from the real pathogen.
Still another approach is to make just a few of the proteins from the pathogen in the lab and inject those. This is called a subunit vaccine. The HPV vaccine is a good example of this kind of vaccine.
Then there are vaccines that don’t involve the pathogen or its proteins directly but rather trick your cells into making the proteins. These involve injecting DNA or RNA packaged in different ways. Some use protective chemical shells—or even other viruses—to deliver the vaccine.
In either case, the DNA or RNA is delivered to the inside of your cells. This then gets your cells to make the pathogen proteins, and those proteins then induce your immune system to develop resistance to the relevant pathogen.
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