How were mRNA vaccines developed so quickly?

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Vaccine development is a lengthy process. It can take up to 10 years to go from a prototype to completed human trials, especially if the disease is not well understood. Yet the COVID-19 mRNA vaccines were developed in less than a year, in part due to the rich development history behind the mRNA platform.

“Google Scholar lists over 250,000 research papers mentioning mRNA vaccines prior to 2020 when COVID-19 wasn’t even known yet,” said Bill Anderson, professor emeritus in chemical engineering at UW, in a panel discussion. “So, in some ways, this vaccine has decades of development work behind it.”

Conventional vaccines, such as those produced by Johnson & Johnson or AstraZeneca, work by injecting an inactive virus fragment into the body. This allows the immune system to learn how to fight against the disease, which will keep the body safe if the virus is ever contracted in the future.

mRNA vaccines use the same concept, but instead of injecting a piece of the virus, they inject an mRNA blueprint. The body can use this blueprint to produce the target virus fragments itself.

Before the pandemic, mRNA vaccines were already being studied to treat the Ebola virus, Zika virus, cancer and other illnesses. This allowed the technology to be quickly adapted for COVID-19.

mRNA vaccines became a popular research topic due to their manufacturing advantages. Conventional vaccines require growing pieces of the inactive virus, which is often done inside the cells of chicken eggs. This is a long and complicated process that can be avoided with mRNA.

“Pharmaceutical products that are manufactured using growing cells can take days or weeks to process from beginning to end. Unlike many traditional vaccines, mRNA doesn’t rely on growing any cells or harvesting them for further processing and multiple purification steps. It can essentially be done in a vat in a few hours,” Anderson said.

Additionally, there was an unprecedented amount of global funding and effort put toward stopping the spread of COVID-19.

“We are used to slow vaccine research. COVID vaccine research has been much faster because of incredible cooperation, coordination, and investment around the world,” said Kelly Grindrod, associate professor at the Waterloo School of Pharmacy, in another panel discussion. “This meant the stages of research were better streamlined, and these factors also allowed for the rapid recruitment of more people into large, well-designed trials.”

Data was gathered very quickly during the human trials due to the rapid spread of the virus. Grindrod explained that community circulation caused people with the placebo vaccine to get sick faster than usual, providing useful data on vaccine efficacy.

Although the technology was developed quickly, that does not make it dangerous. The idea that the mRNA vaccines are unsafe due to unknown long term side effects has been proven false.

“The vaccines are safe. That was one of the main questions answered by the clinical trials,” Grindrod said.

She explained that the vaccine doesn’t stay inside the body forever. mRNA stops making proteins after one week, and the vaccine breaks down completely within six weeks. At the time of approval, both mRNA vaccines had at least six weeks of data in most participants.

The success of the COVID-19 vaccine development program may prompt further research into vaccines for other diseases.

“In the longer term, now that the acceptable safety and good efficacy of a vaccine from an mRNA platform has been proven in humans at a very large scale, this may open up and accelerate further opportunities for treating other diseases,” Anderson said.