To address the COVID-19 pandemic, as with other infectious diseases, a key intervention is vaccination. Health communications are thus of vital importance for informing the public on the benefits and risks of vaccines. This in turn makes the readability of media content fundamental. Previous studies of COVID-19-related information have found the readability of online information considerably more difficult than recommended. However, studies on the readability of information related to COVID-19 vaccination in Asian contexts have yet to be carried out. Furthermore, especially in the case of the current pandemic, health information is communicated by a variety of information channels, including the internet and mass media. This paper investigates the readability of textual information on COVID-19 vaccination found online and in newspaper articles in parts of Asia where English is one of the main languages, namely Singapore, Hong Kong, and the Philippines. Readability was assessed using a set of readability tests (Flesch–Kincaid Reading Ease, Flesch–Kincaid Grade Level, Gunning Fog Index, Coleman–Liau Index, and Simple Measure of Gobbledygook Grade level). It was found that a low proportion of URLs scored within recommended readability thresholds, and did so consistently across locations and types of sources. Furthermore, a relatively low proportion of web searches returned information from local sources; most URLs linked to sources outside of Singapore, Hong Kong, or the Philippines. Further, local online and newspaper sources scored similarly poorly on readability on average compared to non-local sources. Understanding of fast-evolving health communications concerning COVID-19 vaccination encompasses information about vaccine development and deployment from other locations, as well as locally. Nevertheless, these findings indicated a fairly low proportion of local sources among the top search results, and relatively low (i.e., difficult-to-read) readability scores for top search results and for local newspapers. An important issue for health communications strategies addressing COVID-19 vaccination will therefore be to consider different types of media sources in order to achieve the right mix of local and non-local sources while also ensuring appropriate readability.