On March 11, 2020, the World Health Organization officially declared COVID-19 a global pandemic, causing one of the largest disruptions to schooling in history. The COVID-19 pandemic introduced unprecedented challenges for education research and large-scale assessments of student populations. Both schools and researchers were forced to modify their usual practices to protect the health and safety of students and other members of school communities. Disruptions to data collection processes can be especially problematic in large-scale international assessments that study trends within and across countries, such as PIRLS 2021. This report provides researchers with an overview of information about the COVID-19 pandemic that is available through the PIRLS 2021 data. As noted in the PIRLS 2021 International Results in Reading, neither PIRLS 2021 data nor any other cross-sectional international large-scale assessment can be used to make causal inferences about the effect of the COVID-19 pandemic on students' reading achievement, such as "learning loss." However, PIRLS 2021 offers rich contextual information about students' instruction and learning during the pandemic, including their home and school environments and the broader national education systems. The immense disruptions to schooling worldwide during the pandemic period are also important to keep in mind when interpreting the PIRLS 2021 results. This report begins by describing how the COVID-19 pandemic necessitated modifications to the original plans for the PIRLS 2021 assessment, which have implications for interpreting PIRLS 2021 results. The report continues with an overview of the different types of contextual data related to the COVID-19 pandemic that are included in the PIRLS 2021 International Database. COVID-related items from the PIRLS 2021 home and school questionnaires and their international average results are presented. Information about COVID-19 available in the "PIRLS 2021 Encyclopedia" and some key themes are also presented. Finally, the report concludes with key takeaways for researchers wishing to use PIRLS 2021 data.