The latest COVID-19 vaccine formula, developed by Pfizer-BioNTech and Moderna, is a single-shot vaccine that has been approved by the U.S. Food and Drug Administration (FDA). This new vaccine is designed to protect against the XBB.1.5 version of Omicron, which was the dominant subvariant in June when the FDA selected a strain to target this fall.
The primary reason for the rise in COVID-19 cases is waning immunity, which occurs when protective antibodies and cellular defenses stimulated by vaccine or infection diminish over time. The new vaccine is designed to address this issue by providing long-lasting immunity, similar to the annual flu shot.