Prof. Joel Eissenberg has a new post up considering people’s immunity to Covid and what it consists of after vaccination.
COVID vaccine immunity is waning — how much does that matter? (nature.com), September 17, 2021, Elie Dolgin,
We can say circulating antibodies do matter for protection from COVID-19. With the innate immune response, they represent the frontline response in a viral challenge. Often forgotten in the durable immunity response are the memory B- and T-cells. The assays for their activities are much harder to monitor. Ultimately, this part of the adaptive immune system plays an increasingly important role over time. For the vaccinated people, the memory cells are continuing to perform well:
Immunologist at the US National Institute of Allergy and Infectious Diseases in Bethesda, Maryland Doria-Rose;
“Things wane, but not all things wane equally. ‘Neutralizing’ antibodies intercepting viruses before they infiltrate cells might not have long staying power. Levels of these molecules typically shoot up after vaccination and then quickly taper off months later. That’s how vaccines work,”
Cellular immune responses are longer lasting.
As immunologist at the University of Toronto in Canada Jennifer Gommerman explains:
“Cellular immunity is what’s going to protect you from disease.”
Memory B cells, which can rapidly deploy more antibodies in the event of re-exposure to the virus tend to stick around. So do T cells, which can attack already-infected cells and provide an added measure of protection should SARS-CoV-2 sneak past the body’s first line of defense of antibodies.
One of the only long-term studies considering these three planks of the immune system simultaneously evaluated antibodies, B cells and T cells. Researchers found vaccinations spurred durable cellular immunity. Memory B cells continued to grow in numbers for at least six months getting better at fighting the virus over time. T-cell counts remained relatively stable, dipping only slightly over the duration of the study period.
University of Pennsylvania Perelman School of Medicine John Wherry adds;
“So, you have a reserve. Circulating antibodies may be declining, but your immune system is capable of jumping into action once again.”