Researchers at the University of Hong Kong reveal that a timely third vaccination of either CoronaVac or BNT162b2 is critical to induce virus-specific memory B cells and Omicron cross-reactive T cell responses, reducing the frequency of breakthrough infections and disease severity. The study found that the third-dose vaccination provided better protection against Omicron BA.2 breakthrough infections. The research paper is published in The Lancet Regional Health – Western Pacific.