Pfizer, Moderna, and Johnson & Johnson vaccines provide good protection against the virus that causes COVID-19. But how long does that last? Will you need a booster shot? Researchers including Dr. Deepta Bhattacharya, BIO5 member and associate professor of immunobiology at the University of Arizona explains that the vaccines will likely provide at least some degree of protection for a long time because there are so many layers of immunity. The first shots of the two-shot Pfizer and Moderna vaccines provide reasonable protection. Then the second shot bumps up the level of antibodies and T cells produced by the body, he says.