After more than three years of COVID-19, with over 763 million infections and nearly seven million deaths, understanding the effectiveness of vaccines remains crucial even if the WHO has lifted its public health emergency. With this in mind, a team of researchers from the MBMC sought to answer two questions. First, how well does the primary series of COVID-19 vaccines protect people (against infections, hospitalizations and deaths) four months or more after completing vaccination? Second, how well does the first booster dose protect people three months or more after receiving it? Answering these questions will provide invaluable information for policymakers to make evidence-based decisions, such as the timing of administering COVID-19 vaccine booster doses.