The idea of waning immunity has picked up steam in recent weeks, with some countries using it to justify rolling out third-dose COVID-19 vaccine boosters to their populations. But immunologists say the concept has been largely misunderstood.
While antibodies – proteins created after infection or vaccination that help prevent future invasions from the pathogen – do level off over time, experts say that’s supposed to happen.
And it doesn’t mean we’re not protected against COVID-19.
Jennifer Gommerman, an immunologist with the University of Toronto, said the term “waning immunity” has given people a false understanding of how the immune system works.
“Waning has this connotation that something’s wrong and there isn’t,” she said. “It’s very normal for the immune system to mount a response where a ton of antibodies are made and lots of immune cells expand. And for the moment, that kind of takes over.
“But it has to contract, otherwise you wouldn’t have room for subsequent immune responses.”
Antibody levels ramp up in the “primary response” phase after vaccination or infection, “when your immune system is charged up and ready to attack,” said Steven Kerfoot, an associate professor of immunology at Western University.
They then decrease from that “emergency phase,” he added. But the memory of the pathogen and the body’s ability to respond to it remains.