What is a primary source of information on mask effectiveness during the pandemic?

The World Health Organization (WHO) is recognized as a primary source of information on mask effectiveness during the pandemic because it is a specialized agency of the United Nations that is responsible for coordinating international public health efforts. WHO has conducted extensive research, compiled data from global health authorities, and provided guidance based on evidence regarding the use of masks to prevent the spread of infectious diseases, including COVID-19. Their reports and recommendations incorporate the latest scientific findings, making them a reliable reference for understanding the effectiveness of masks in curbing transmission.

While other organizations, such as the CDC and FDA, also provide valuable information regarding public health and safety practices, WHO's global perspective and comprehensive approach allow it to serve as a key source for information used in various countries, aiding in the establishment of health guidelines and practices worldwide.