Although indispensable for improving health outcomes, medicines and vaccines or their administration and use can produce adverse effects, requiring continuous vigilance to ensure that the benefits outweigh the risks. Monitoring the safety of the use of marketed medicines and vaccines, also known as pharmacovigilance, should therefore become much more explicit in efforts to strengthen health systems and prepare for public health crises and normal times because the world is determined to build back better after the COVID-19 pandemic. The objective of this report is to examine the importance of pharmacovigilance in a health system both during a health crisis and in normal times, describe the function, structure, and processes of a functional pharmacovigilance system, and explain the value of drug safety monitoring in building resilience in health systems post-COVID-19 pandemic.