As the COVID-19 virus spread rapidly around the world, information related to the pandemic also spread quickly and in massive amounts. Uncertainty and unknowns about the pandemic together with the explosion of information created confusion and fear among many populations. A major challenge for public health practitioners is to provide clear and consistent messages that can be understood by different types of audiences, including vulnerable populations such as pregnant women and children who are often forgotten in this process. We compared and analyzed the development processes of health communication products for pregnant women in Madagascar and for elementary school children in Japan during the COVID-19 pandemic. This study compared these two field experiences in different socioeconomic settings to identify common strategies for the development of communication materials in a health crisis