Mix-and-Match Covid Boosters: Why They Just Might Work

Immunizations typically consist of two or more doses of the same vaccine. The Moderna vaccine, for example, is administered in two identical shots of mRNA, separated by four weeks. A double dose can create much more protection against a disease than a single shot. The first dose causes the immune system’s B cells to make antibodies against a pathogen. Other immune cells, called T cells, develop the ability to recognize and kill infected cells. The second shot amplifies that response. The B cells and T cells dedicated to fighting the virus multiply into much bigger numbers. They also develop more potent attackers against the enemy.