Turning our bodies into vaccine factories
As I write, it’s almost a year to the day since the first reports emerged of the mysterious illness we now know as Covid-19. The virus responsible, Sars-CoV-2, has turned the world upside down. But in that time, we’ve also made incredible progress developing vaccines for Covid-19. We’ve gone from nothing to having almost 20 in phase III clinical trials, some of which are being rolled out across the world. It’s quite an achievement and a testament to what we can accomplish when enough money and people are thrown at a problem.
The tried-and-tested ways to make vaccines involve giving people a dead or weakened version of the infectious microbe, or the parts of it we want our bodies to learn to recognise. But the Pfizer/BioNTech and Moderna vaccines being rolled out take a completely different approach.
They turn our own bodies into the vaccine factories. If the approach turns out to be safe and effective, and things look promising, it’ll revolutionise the way we design and make vaccines in the future.
How do we turn our bodies into vaccine factories? Inside our cells is a compartment called the nucleus where our DNA lives. That DNA is the instruction manual for creating proteins we need to function.
DNA isn’t able to leave the nucleus. Instead, it gets turned into instructions that can leave, called ‘‘messenger RNA’’ or mRNA. That mRNA goes to our cells’ protein-making structures to be translated into proteins, and then degrades.
The advantages are it is relatively quick, easy, and safe to make mRNA. The disadvantage is mRNA is unstable, so while it can last a long time in the freezer, it degrades quickly at room temperature.
The Pfizer/BioNTech and Moderna vaccines are synthetic bits of mRNA designed to make our cells manufacture the spike protein of the SARS-CoV-2 virus. That’s the part of the virus we want our body to recognise so when we encounter the real virus our immune system will protect us from it.
Scientific breakthroughs like this don’t come from nowhere. Messenger RNA was discovered in the early 1960s but it wasn’t until the late 1980s that scientists learned how to make it from scratch. Then a new hurdle emerged. When scientists injected mRNA into animals, it induced such a severe immune response that the animals died.
It was Dr Katalin Kariko, working with immunologist Dr Drew Weissman, who figured out how to stop that severe immune response. That was crucial for mRNA vaccines to be trialled in humans. She’s been at the helm of BioNTech’s Covid-19 vaccine development. We owe her our gratitude.
[In 12 months] Sars-CoV-2 has turned the world upside down.