When Betsy Thorpe, 52, a book editor in Charlotte, North Carolina, heard about a clinical trial to test a COVID-19 vaccine last summer, she jumped at the chance to roll up her sleeve. “This pandemic is really shutting down the economy and killing people, and many people have long-term side effects,” she says. “It was the least I could do to try and get rid of this.”
The trial Thorpe joined was for one of two novel vaccines using what's known as messenger RNA, or mRNA, now approved for emergency use for COVID-19. They represent a fundamentally different way of protecting people from disease.
Traditional vaccines, like those for measles and flu, insert a weakened or inactivated germ into the body to trigger an immune response. Not so with mRNA vaccines. They work by sending the genetic instructions to build a single part of the virus (with COVID-19, the “spike protein” found on the surface of the virus's cells), creating what can be described as a memory of the virus inside your cells. With that genetic information in place, when your body encounters the actual virus, it reacts by making specific antibodies that block cells with this signature protein from infecting your cells.
"We insert the genetic code for that protein directly into your cells and you become the factory for making your own vaccine,” explains Deborah Fuller, a vaccinologist and professor of microbiology at the University of Washington School of Medicine.
So far results from trials suggest that the vaccines using such science are highly effective — 94 to 95 percent — at protecting people from COVID-19. “We've never seen a vaccine for a respiratory virus infection with this efficacy” in humans, says Drew Weissman, M.D., a vaccine researcher and professor of medicine at the University of Pennsylvania Perelman School of Medicine, who helped develop the technology used for both the Pfizer and Moderna vaccines. “Influenza is around 50 percent. Most others are 70 percent.”
The vaccine's unique immune system advantages
Why is the approach so effective at thwarting the virus? In addition to producing antibodies, mRNA and other gene-based vaccines also recruit powerful immune cells, called T-cells, into the fight. “If the virus escapes the initial antibody barrier and gets inside our cells, they become invisible to antibodies,” says Alessandro Sette, a professor at the Center for Infectious Disease and Vaccine Research at the La Jolla Institute for Immunology.