Your questions, answered "Are any tests being currently conducted on people with two doses of Moderna or the Pfizer vaccine to see how their antibodies decrease month to month?" — Alice in Virginia Yes: This is an active area of study. In general, according to the first set of long-term reports, antibodies appear to persist for months post-vaccination. "From the efficacy studies through at least six months, it's reassuring these vaccines work very well," Mehul Suthar, a viral immunologist at Emory University, told me recently. "It's quite remarkable as to what the scientific community was able to achieve by developing these vaccines." Why are these antibodies important? Neutralizing antibodies are molecules that, simply put, stick to viruses. This hinders the ability of a pathogen to slip through a cell's outer layer. But because antibody molecules don't last forever, a human body must constantly make new ones. And, over time, antibody levels can wane. To study the durability of neutralizing antibody levels, Suthar and scientists like him sample the molecules from patients' blood after vaccination or infection. A lab test can show whether these antibodies stick to certain pathogens – like the novel coronavirus or, often, a harmless virus designed to resemble it. Suthar and several co-authors, as they reported in an article in the New England Journal of Medicine, observed decreasing antibody levels in people fully vaccinated with Moderna. But those molecules were plentiful enough to remain detectable for all six months of a study period. A similar study involving the Johnson & Johnson vaccine also shows declining but durable antibodies at six months. The levels of neutralizing antibodies dropped by about two-fold. Study author Dan H. Barouch, who directs the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center and whose lab helped develop the J&J shot, described this as "very good durability of the vaccine." Whether antibodies will last for a year or more after vaccination isn't clear yet, because the research moves in real time. "We have to wait for Father Time," Suthar said, "to be able to run these experiments." Antibodies produced at six months "will certainly block infection with the wild-type virus," Suthar said, referring to the original form of the novel coronavirus. Studies are underway to determine how well post-vaccine antibodies fare against the emerging variants of concern, such as delta. These antibody results alone won't dictate whether we need booster shots. For starters, neutralizing antibodies don't work solo — there are other defenders within the immune system. Vaccination produces T cells that recognize and kill cells contaminated with the coronavirus. Those cells have been documented in people six months after immunization, too. | 
Email 
