The production of antibodies is a key immune response to viruses, bacteria or other pathogens, but it’s not the body’s only way of fighting infection.
Booster doses are seen as a way to shore up the immune protection against SARS-CoV-2, the coronavirus that causes COVID-19.
But some experts are questioning whether booster shots will be needed or if our immune systems are robust enough to not need additional vaccine doses.
As some countries roll out booster doses of COVID-19 vaccines, conversations over whether these additional doses are needed right now have centered on three things — breakthrough infections, waning antibody levels, and the Delta variant.
The concern is that as antibody levels decline during the months after full vaccination, people will be less protected, especially from the highly contagious Delta variant, which could increase breakthrough infections.
Booster doses are seen as a way to shore up immune protection against SARS-CoV-2, the coronavirus that causes COVID-19. However, the booster shot debate is more complicated than this.
When talking about how well COVID-19 vaccines work over time, there’s not only one type of effectiveness.
Some vaccines might still prevent most people from getting severely ill or dying but may have less protection against infection that leads to minor symptoms. In addition, antibodies are only one tool used by the immune system to fight infection.
Focusing solely on antibody levels misses the protection offered by the other parts of the immune system, some of it longer-lived.
Still, it’s important to understand how antibodies work and what waning levels might mean for protection against COVID-19. Antibodies are Y-shaped proteins the immune system produces in response to an infection.
They recognize and bind to specific molecular structures — known as antigens — such as those found on the surface of a virus or bacterium.
Many of the antibodies involved in preventing coronavirus infection bind to the virus’s spike protein on the surface, which the virus uses to infect cells.
Antibodies are produced by immune cells called B cells, found in the blood, lymph nodes, spleen, and other tissues. Each B cell produces a specific type of antibody.
